2002 xt600e engine rebuild/replacement questions
 

hi there

disassembling engine after the session of excessive smoking.
broken piston skirt and some vertical crack on cylinder wall for now :thumbup1:
more details and photos bit later.

for now just curious to know, *IF* it's only about piston and cylinder, which years/codes to avoid as a replacement?
also, is cylinder sleeve (separately) could be a reliable solution (press fit etc.)?

considering mileage (reaching 170k) and overall amount of scars, used to think about new engine as well even before this issue. same question here, which years to avoid in terms of fitment?

Hi, yes best is to find a used low mileage, years from 90-02. The 96-02 best engine with, gearbox issue sortet 5th gear and top cover welded differently so it wont crack. You can change sleave, you have bits of piston all over engine so it must be teared apart.

thanks for info.
will try to go with 96-02 engine option, but so far not sure if current budget will allow this, so maybe will have to find cylinder-piston kit instead.
how about earlier years in such case? checking some stuff online and so far older cylinders visually look similar...

meanwhile, here's the main character of the dark story above -
https://i.imgvibe.com/2024/01/29/piss.jpg

yep, some archeology must took place in the engine. oil rings were also broken (partially), luckily, at least their remains were successfully captured by the magnets.

You dont know what was captured or not before entire engine is dismantled, dont take easy shortcut changing cylinder/piston and start up.. End up with new failure and heavy damage on cylinder walls/piston. Before 90 it was 2kf cylinder, after its 3tb up to 02, its expensive for piston wiseco is 190$ + cylinder. Total overhaul with gaskets and bearings + some workshop help is fast 1500$. I would think its easy to find a used old bike one for 2-3000$.

thanks again for infos.
guess after finishing the engine disassembly will have more clear idea as well as further plans.

If you doing rebuild buy new rod with bearing when you first have to dismantle everything, i would never reuse the rod bearing after this. And maybe a part of the reason piston failed is slack in that bearing. Anywaysits importan to do maintence before this happens, no piston last forever, pre change parts is alot cheaper than total rebuilds after all is crashed.

ok, will have a closer look after having crankshaft out. for now i don't feel any slack vertically, only slight lateral free play which i guess is normal.
as for maintenance you're right. sadly, this trouble happened just couple weeks before the winter's planned check-ups and service. more attention probably will bring more luck next time )

What is the concern is bits and damage in the bearing, it can feel ok now but fail later after rebuild and you are back to start again. Same goes for all bearings at this mileage, do all or nothing is my advice. A piston change around 100k km is a good solution, offc it depends on how bike have been used and oilservice. If people dont know its not a big cost and can save alot of problems with piston change, oversize and bore cylinder + gasket, i will do the valve seals when its open. These engines are so easy to work with vs a 4cyl so there is no excuse to ride untill it breaks and tear up everything. In worst case you will end up in a an accident with rear tire suddenly lock up in highway in heavy traffic...

Btw good luck removing rotor, if its stuck like mine was its worth buing a 6t cylinder hydraulic jack.

yep, right point.
somehow, rotor used to be not a big deal in my case. considering earlier experience, nut of the clutch basket seems more challenging for now )

As someone who builds a lot of engines and buys and sells a lot of bikes, I think it's generally a terrible idea to buy a twenty year old second-hand engine unless you've seen it running well in the bike it came out of. Or can verify it some other kind of way.

80% of the engines I've bought on the second hand market have needed expensive work. Or have been scrap. Or worse than the engine it was bought to replace. It's obviously not always that way, but its a huge lottery in time and money.

It's generally why they're for sale. It's a scammers market. A motor is impossible to test properly until it's been built back up. And then you have no come back anyway as you've worked on it yourself. MEH !!!!!!

Over the years I've learned to just rebuild what you've got. And do it properly. It can be expensive. But generally less expensive than pissing around with lottery engines or doing half repairs.

The XT600 engine is a simple motor. You've gone this far. It's now very easy to take it down further and replace the crank or have the crank rebuilt. £200-£300. You can also then clean everything out of the cases and check everything else.

Measure and inspect your connecting rod. Replace if necessary. It could have been rod knock that caused the failure. Not uncommon on a high mileage XT.

Then you build it up with a new piston and rings.

The XT has a cast-iron liner. You can remove it easily just by heating the barrel in your oven at about 120c. Suspending on some fire bricks or metal blocks. It will just fall out.

A liner is about £150.

Good luck

lot's of good and useful infos as well as experiences here.
thanks a lot sharing all these stuff.

indeed, engine disassembly is progressing and more facts will appear with time.

thanks again!

meanwhile, progressing with disassembly.
side covers, rotor, clutch, gears etc. are off.
already collecting piston pieces.
there's some fine debris in the oil filter, not attracted by magnet, seemingly aluminum.
oil pump seems alright, with slight dents on the edges and very few/slight circular marks (not even grooves) on the flat parts of internal gears. could be worse.
but outside gear (plastic one) has clear signs of wear.
not as much, but driving gear of the pump, located below the clutch basket (also plastic) is also not in the best condition.
https://i.imgvibe.com/2024/02/07/kup...uw-91-95_2.jpg
(photo for reference)

now just making sure, if it's about the replacing this drive gear, seems i'm gonna need clutch basket as a whole, right? it doesn't look to be made to disassemble easily...

Yes its correct its a unit basket 400$, cant see from pict what is damaged.

Buy from Germany, good buy and use yours for spareparts or sell as is.

https://m.mobile.de/motorrad-inserat...6c3c50&type=ad

and import it & register it in Georgia? Should be fun....

whats the problem?

thanks for info. picture is random, since haven't made it of my part.

yep, that "fun" roughly adds 20% on the price.
considering current budget, it's out of question this year.

meanwhile, cases are split and stuff is out.
collected nearly all pieces of piston.
gearbox is alright, no worn teeth or dogs.
sadly, not the same with the crank. so far was unable to measure runouts, but other measurements are not very promising - https://i.imgvibe.com/2024/02/08/cranck.jpg

guess at least new bearing is needed. after finding the way of measuring runouts, further decisions will come.

Ok, bearing and rod, dont use old if you first take the shaft apart. If you havent changed any bearings around its time to do them all, how about the head cam etc any wear
marks?
Was the rotor stuck or did it come off easy? The problem is that with all you need for doing this complete rebuild its no low budget build, do it all or you will regret later when you have to start from beginning.

thanks, will consider the new rod as well.
head & cam were looking good, haven't checked valves and springs yet. but cam chain was almost to the end of its life, tensioner had one last position left.
rotor was not very stubborn. came off pretty similar like last year when had to replace the starter clutch - good pressure with diy puller + one good hammering.
yup, this rebuild is still pricey than expected. although, the reserve of some spares (gaskets, chain, clutch etc.) collected earlier somehow help. also, maybe couple friends abroad (greece and germany) will be able to find and send used parts in good condition, this also might make the life easier, let's see...

Ok, yes been doing alot of buying from Germany earlier years, it was alot of parts and good price. But lately its not the same, prices is really high and not much good used parts. Here you cant find used parts for those, still good buys on good bikes low km. Good luck getting bike on the road again:scooter:

thanks a lot for a good wishes! hopefully, not too much of the spring will be missed..
meanwhile, checking some options of con rods and even used crankshafts online. this later is sometimes listed with appropriate measurements as well, making option to consider. all this leads me to the new question - are there any year or model (xt/tt) difference for con rod and crankshaft?

Its only years from 90-2002 3tb

another important info, thanks again!

conrod kits from PROX are relatively cheap and quite well made, had one in my racing supermono. easy to find in ebay.


question is if you have a decent shop who can put it back together with the right alignment.

thanks for info. seems they also have pistons and other parts which i'm gonna need sooner or later.
yep, that question about decent workshop is very exact and actual. still have to check couple remaining options but expectation so far is not very optimistic.
that's why considering maybe whole crank/rod set (used..), assuming that someone will be ok/able to measure at least free plays. let's see.

hi there.
after lots of online searching, direct and indirect communications and finally, shipments, i'm having some updates & questions.

living in a country where there's no place to assemble/align crankshafts and machine the cylinder sleeves to fit in the block made me to look for the whole crankshaft & con rod set, as well as cylinder & piston kit. used ones.
and this items with some other parts (strainer, pump gear etc.) are already in my garage.
some remaining small stuff is still on the way.

well, crank seems within specs (but still without any info about runouts).
but piston and cylinder are at least worth asking some questions.
with the depth and accuracy of vernier caliper, cylinder inside diameter is about 95,7mm.
piston seems oem (that izumi and yamaha markings inside) but it's larger compared to my late standard one. and having different, cylindrical skirt, not 8-shaped one i was expecting.
can't compare their weights because of broken part of my older piston.
visually "new" piston looks pretty clean and undamaged, but there're some differences in the diameters, which also seem strange -

https://i.imgvibe.com/2024/03/27/c1.jpg

https://i.imgvibe.com/2024/03/27/c2.jpg


planning to show cylinder and piston to someone more experienced in this domain for precise measurements and overall assessment. also, let me ask some questions here as well -

1. that ~95,7mm of inside diameter of cylinder indeed indicates some overbore. 3rd step maybe?

2. what about different diameters of the piston? ok, having smaller top is maybe normal (like that 94,3mm on my older one) but how about different diameters on the bottom?

3. will that different skirt be a problem? if it's heavier, for example...

4. in the case if i'll decide to keep this set, will i need appropriate head gasket for it or it's not related to oversized cylinder?

From dimensions, sounds like you bought a +0.5 piston/cyl



but in any of these measurements you need to at least work with a digital caliper...or better a mictrometer, vernier not good enough, but thats only for external diameter, and yes, the point ot measure is more on the skirt than the top



for the cyl diameter you really need special equipment to measure.



luckily, there is a work around: put your piston mid stroke in the cyl in the right orientation and see what size feeler gauge fits between skirt and bore. thats essentialy your clearance. according to the manual it shouldnt be more than 0.1mm limit , but seen bikes run reasonably ok with even more than that.

hope you open the manual from time to time becuase its quite clear on this

thanks for infos.
yes, for now main concern is about cylinder dimensions which probably i'll have measured professionally in the upcoming days.
will remember that good trick with the feeler gauge as well.
about manual you're right, somehow overlooked that part in the beginning, seems my file was being scrolled mainly around engine disassembly section )

there are dims also for cyl there, remember to add +0.5 as you are 1st oversize

guess you meant 2nd oversize along with +0.5...
anyways, i'm having following results from today - micrometers in experienced hands stated that i'm having indeed fresh +0.5 piston together with also freshly re-bored and honed cylinder to the size of 96mm...
so yes, remaining 0.5mm was a clearance. and i was recommended to get appropriate, i.e. 96mm piston kit.
later today also double-checked this results by myself, mainly because to observe how that feeler gauge method works. well, it works pretty well, as expected.
hopefully one guy in greece will be ok to get his piston back and refund.
luckily, there's plenty of choice of new 96mm kits online.

try contacting prox they shgould have all oversizes, decent quality

thanks, yes, they indeed have a whole spectrum.
also trying to find a matching head gasket.
meanwhile, case halves are back together.
parts search and shipment will cause further delay, hopefully, shorter this time.

Head gaskets are always a bit bigger than the stock bore, so don't loose sleep over that.

well, measuring my existing spares against this 96mm cylinder also shows that.
no clear/particular search results about oversized gaskets was another factor.

but somehow was still uncertain, as never had an experience with rebored cylinders and opinions across the internet were not in the clear consensus.
also, as the slightly curved profile of the gasket seemingly will expand inside towards the cylinder at some extent, that also created some suspects.

anyways, reading the stuff here is more solid argument, thus i'd happily stick with my existed spare gasket.
so thanks, some amount of sleep, time and money had been saved ))

if you look into any online oem parts catalog, youll see that yamaha offered up to +1.0, but no oversize gasket. just to remind you, we are talking 0.5mm per side...


things get complicated only when you go for a big bore lit thats several mm's bigger

yep, that also makes sense.

hi there.
progressing with the engine assembly, and having one question about oil delivery.

engine is assembled but not yet in the frame. decided to check the oil delivery before this step.

so, all hoses are connected to the engine, and with some oil inside, spun the crank for few seconds.
as a result, i'm receiving some oil to the pipe going up to the frame -
https://i.imgvibe.com/2024/05/03/pipe.jpg

but nothing at the filter cavity here - https://i.imgvibe.com/2024/05/03/fil.jpg

ok, i understand that there're not proper pressures in the system as it's not a closed circuit as the engine is not connected to the frame and so on, but even in this case, could that tiny spring behind the ball valve blocking the main flow?

p.s.
well, in order to clarify oiling diagram better, browsing random images of the open crankcase in the web somehow helped.
seems the engine must be connected to the oil tank in the frame to have some oil delivered into the filter cavity.
let's see.

Guess you didnt have enough oil in bottom for it to come up in filter and not turning fast enough. Tell us what have been done with engine?

main repairs in the engine were replaced crank&rod, cylinder (96mm) and piston.

meanwhile, engine is back in the frame and oil is filled up.
i was turning it with starter motor, connected to 12v.
gave it two 5-second long try, but still no oil in the filter cavity.

guess some oil must be in the bottom and pump is working (as oil goes up to the frame).
what about the normal speed of the starter motor - isn't it fast enough?

maybe i'm bit anxious on this subject, but for now don't want to start the engine without being certain that crank and cam will be receiving oil..

Yes oil should come out the pipe return from engine when using starter motor if you fill enough in bottom, try blocking the return hose and get pressure enough to send ip in oilfilter. No bearings changed in casing?

thanks for advice, i'll try it on tomorrow, otherwise thinking to take the pump out again and re-check the passages...
guess, somehow oil pump must be working in two ways more or less simultaneously; from the strainer up in the frame and from the frame through crankcase towards the filter.
but how exactly this second link is done so far is bit vague to me.
https://i.imgvibe.com/2024/05/06/Untitled-1.jpg

as for bearings, haven't retied them so far, except another one (right side) of the crankshaft.

this day appeared pretty remarkable due to couple reasons.
removed clutch cover etc. and inspected oil pump.
and discovered that oil pump also has two parallel circuits... strangely, earlier upper thinner part was staying as one piece and i had no clue about it's existence, overlooking that section.
and all the maze of xt's oil delivery now is finally clear.
guess was lucky enough to receive all this knowledge in pretty unforgettable ways.
and this admonishment from the manual also makes much more sense -
but! somehow the manual still goes short about pump, for example, i can't find any indication that there must be two set of rotors to inspect, or applying oil into the passages of another circuit as well (two smaller holes below), which i also involuntarily skipped last time...

anyways, bike started pretty nicely on the first try and gave long-lasting smile.
bit of the remaining work and long-awaited break-in period is about to start.
besides of general "keep it smooth and slow-ish", if there're some bike-specific advices about break-in period (new crank/cylinder/piston), and how long (one tank? 500km? more?) please let me know.

No 30-40km is enough, most importan is start up fast dont let it idle, ride with 50- 75% load up and down and then 100%, good oil and change. The ones who get the most power is the one who has the roughest breakin in.

well, thanks for the suggestions. "the most power" is not exactly what i was particularly looking for, but approach makes a good sense.

Well you do what you think is best for your engine, just dont crank alot, prime up carb and hope it starts on first turn with good oilflow, then various rpm and your good:scooter: The bad part is for my understanding that you already have done alot of cranking looking for oilflow...

you're right, there was some pre-run cranking.
at least, everything inside was well soaked into the oil, which hopefully could had survived before the first run...
had first short ride today and despite of not yet tuned carbs (pilot and maybe primary as well needed some attention from the last time), after all this time it felt so nice... :mchappy:
generally, i'm following your suggestions. was varying throttle without hesitations, but still didn't went above the third gear this time.

Good to hear you are on the road again, what break in oil are you using? Keep it up to 70% load in beginning, remember wrong fule/airmix is not good either for breakin in and remember dont leave on idling and low rpm above 1500 is good.

oil is 10w40 semi by rheinol.
mixture must be bit richer than normal, will address this issue soon.
as advised, idling time is minimal.
by the way, does this engine need checking the torque/retightening of head bolts after some time?

Ok, its not recomended using semi or synthetic oil, use break in oil! No its ok with headbolts torque.

Break-in oil is specifically formulated to seal the piston rings against the cylinder wall for maximum engine compression and power. Break-in oils use conventional base oils without friction-modifier additives to allow controlled wear between the rings and cylinder wall.

well, that's another piece of knowledge getting by hard way.
tried some local search, for now found one option for car engines.
for now about 20km is done. any suggestions what could be done in the given situation?
meanwhile, fingers are crossed that no big trouble will take a place..

I dont know about the cylinder job, is it properly done with machine honing? If not it doesnt matter, you are in a spot now beyond changing oil to repair seating and maybe glazing the cylinder wall. Ride and enjoy:scooter: Ride for 20km and do a compression test you will know more. Dont forget to change oil and filter less than 150km.

thanks for infos.
cylinder has some weird story behind (together with some other piston, wrote about it earlier).
to put it shortly, i was surprised by receiving oversized cylinder.
then it was checked and measured by someone experienced, who's approved the surface condition and dimensions. and according to him, it was machine honed just recently.
ok, let's see the results of compression test.

ok, it took me a while to get some free time. was unable to find comp.gauge with compatible thread so had to craft it.
so far cold measurement only. slightly above 8 bars.
https://i.imgvibe.com/2024/06/05/comp.jpg
hopefully it could reach 9 (minimum value, according to manual) when hot.

but for now some other problem appears in the primary carb.
slide valve seems worn and adjacent areas inside the carb body as well. besides the not smooth throttle response guess this makes complicated to set mixture right.
as a temporary solution thinking about getting another slider but generally seems like new body is needed.

are you opening the throttle fully when doing the compression test?

carbs were off for adjustments, hence the cold measurement.
maybe will manage to do it on the hot engine as well next week.

yes, 8 is a bit on the low side, but dont know how accurate your tester is, I would at this point ride it and watch out for smoke


dont baby it when running in,
don tkeep it idling, ride on and giving it some throtlle every now and then is best

thanks, basically that's what i do for now.
beside the carb-related issues, otherwise the engine feels and sounds pretty well. ok, i know that i could be somehow subjective as well, after all this period of deprivation. time will tell...

carb situation for xts is getting difficult, not many used good sets around, quite a few people adapting twin CV carbs cinese copies from the Raptor quad... needs some fabrication though

yep, remember some earlier threads from here as well. and even if fabrication wouldn't be needed, don't think that the lack of the slide carb would be enjoyable.
since my cv part is good, there might be bit more chances to find some used set with healthy slide part and wear/damages elsewhere.
again betting on Greece; generally used to find decent amount of options there with lower prices compared to items listed online. although, quality of communication and level of trust varies.

plenty of single cyl bikes use "only CV" no slide, work just fine, same for the raptor itself that utilizes our engines (more or less)

Good luck finding a decent slide carburetor.... if you dont, then you have this option

https://www.ebay.it/itm/266347835292...QwwwvDYsAAAAAA

well, thanks for these infos.
yes, it's clear that cv type is pretty "default" setup.
despite of some intricate character of that "ydis", still thinking that it's very nice solution - slide until midrange, where throttle feel and feedback seems more enjoyable and maybe important as well, and cv for high revs for more smoothness.
at least that's how i get it.
so let's see whether i'll be able to find some decent replacement.
othervise, that double cv seems also good option. i see it needs both intake manifolds with similar output diameter (the bigger one). furthermore, what about stock airbox? that custom pale green parts are for this or for some other reason?

its not my bike, its form a thread in thumper talk


https://www.thumpertalk.com/forums/t...-carb-upgrade/


some tips on jetting too


dont know the details, the guy obviously preferred to put two "sock" foam filters instead of modifying the airbox. like i said, there is fabrication involved also with the thorttle cable



you might like the slide, but there are also disadvantages to it, and if you dont find a REALLY good one, its surly not going to deliver that beautiful feel and feedback that you mention.


unless you can hold that used carb in your hand and test the slide play, you are in danger of ordering used parts that are no better than yours...


my 2 cents

call it "2 cents" but it's indeed good advices & infos (including link). thanks for all of these.
as for testing, chances are that a friend residing in Greece might be able to help. that could be a best scenario. knowing that srx600 also runs the same carbs (at least body) maybe will increase the chances. and of course, it's nice to know that there's reliable plan b as well.

there was this super friendly guy in greece from the forum, maybe try to pm him


https://www.horizonsunlimited.com/hu...bers/nickargas

yes, now i remember him, thanks for this idea.
and pm is sent, let's see...

meanwhile...
 

delayed solution (as usual) made stronger recoil..
so, searching for replacement carbs took a while.
besides the varying quality of throttle response, riding was enjoyable until the recent sudden breakdown.
worn slide piston inside the left carb got stuck and misaligned. or in opposite order. before realizing what it was about, most likely by twisting throttle made it even worse - two screws inside the slide went off, quickly swallowed by engine.. at least engine was running minimal time after this.
considering results, maybe still lucky.
new piston shows almost no traces.
seemingly cylinder wall needs honing (will be followed by proper break-in oil at least this time..).
had valves and seats checked and re-faced. no issues there.
but having this wounds in combustion chamber:
https://i.ibb.co/Tcd6K70/scr.png

according to this damage, what could be the effect on combustion? do they need to be filled?

nothing to do there, dont even touch them


but seriously, the only two screws on the slide are the ones holding the needle retainer/lifting plate, and they are ON TOP of the slide, engine cant such them in.... unless wrongly mounted.



sounds like some serious miss-assembly, so go stand in the corner

well, maybe i indeed deserve to stand in the corner, but for some other reason; like taking the ways of assembly of stuff as normal, repeating it afterwards and not always double-checking with manual..
anyways, have already ordered raptor's carbs along with some rubbers and jets. hoping to adapt it to existed airbox. let's see if it will be manageable.
ok, cv only but at least it will be better than hopelessly damaged carbs.
btw, by some nice coincidence, recently linked infos in the neighbouring thread (Yamaha XT 600 personalization) seem to be very helpful for me as well.

i think carbs will be easy to mount if you order also the raptor manifold and rubbers


most of the pain i expect to be at the airbox / filter side


i just recently mounted different carbs to another bike (not yamaha) these uni filters are super easy to fit, come in all sorts of sizes and even if they hit something, no issue, they are foam :)



i think thats the type used in the pictures i posted.


in my applcation i used the black UP-4200 ones


just measure you aproximate diameter the the carb enrtry ans see what is longest you can fit in there


https://unifilter.com/online-catalog...n-air-filters/

turboguzzi, thanks for good thoughts and ideas.
yes, i've ordered some raptor's rubbers as well, but with a plan (so far) to keep the original airbox etc. let's see.
but obviously, i'm just at the beginning of lots of attempts, headscratches, trial-and-error and so on.

meanwhile, honed (hopefully) the cylinder.
generally, seemingly due to the lack of mounting equipment, local shops always refuse to bore or hone single cylinders here.
so, tried to do it by myself, with a sandpaper and oil.
https://i.ibb.co/JdKkWmv/hon.jpg
seems more or less like a hone. at least not glazed. hopefully, piston and rings will agree to this as well.

also, now looking for a break-in oil. most likely i'll have no big choice here - maybe will end up buying one made for car engines. will have better idea from the next week.

having this question - before assembly, i'll cover cylinder walls, rings etc. with a break-in oil. old oil will be drained, but what about that ~0.5L remaining in the engine? could it affect break-in process (considering that maybe viscosity will be different as well)?

flex hones from ali express cost very little...



fill with mineral oil, do a short, strong break in, then change to whatever full synth or semi you use normally.


dont baby it driving at 50 when breaking in,


load it properly in short bursts, not constant speed. all breaking is for is making the rings seal, you have to load them with pressure. if you go slowly, the new rings will not adapt to the bore.

yes, flex hone was also an option, but besides the shipping time, finally decided that being completely inexperienced in this, achieving needed pattern (more or less..) would be easier with sandpaper and slow progress..

simple mineral oil indeed seems a proper alternative of dedicated motorcycle break-in oil, which anyway seems hard (if not impossible) to find locally. thanks a lot for this hint, maybe i'll get mineral oil for bike engine even with matching viscosities.

and indeed looking forward to do that well loaded break-in when time (and parts...) come.

Sad to hear you are stuck again and summer almost gone... Honing with sandpaper? If you doing this again atleast buy honing brush!

https://www.staypro.no/maskiner-verk...oaAjiTEALw_wcB

generally, i don't ride during jan-feb, so still looking forward to nice autumn rides.
and thanks for the link; let's see what/when i'll have to hone after this, but will consider dedicated tool for that.

i understand that life situation poses some challenges, but not sure your engine will understand.... your DIY hone might or might not work, we dont even know what grit you used, if it was emery cloth or plain sand paper and even if i knew, i could never tell if it'll work

in my 45 year of wrenching, I never did it by hand, neither heard about anyone doing it. draw your own conclusions

your motor, your choice.

By the way, if you use google translate on xtrock's link, you will even see the are noting all the paramters to reach good honing,

regretfully, that link goes up only to 60mm bore, youll need bigger than that of course


this ones are also cheap and adapt to any bore


https://www.youtube.com/watch?v=lSqgJh0Ed5o

Well i didnt link for him to buy here, it was for him to find correct tool for job, offcourse it will have to be correct size, you write like others are idiots here! You dont get the perfect cross honing with your link, cross honing is what machineshop use so ye buy it. https://www.mscdirect.co.uk/abrasive...ning-tools?p=2

well, indeed agree about the risks of not achieving needed finish.
but still had decided that this attempt at least would be better than leaving cylinder wall like it was - with the signs of glazing...
"tool" was plain sandpaper (320) along with the engine oil.
and i do realize that in the scenarios like this at some (increased) extent will have to rely on the crossed fingers..

well, meanwhile carbs arrived. as noted earlier, finally decided to try ones from raptor 660 (chinese copies).
first impression was about weight - 200grams more than original kit.
then, about cleanliness - just ok, not super-clean. no big deal since there's lots of studying / tuning times ahead, naturally involving cleanings as well.

Cant imagine you get any quality that will work over time for 35euros, let us know the fuel consumption, bet its not accurate. I was down to 0,34l 10km last trip with KN filter, fully exhaust Yoshi and stainless downpipes + dynojet kit. Good luck!

sounds you've got pretty nice kit on the both sides of the engine )
well, considering that during the last month or so bike consumes 0 fuel, feeling that any positive number will be better..
also, pardon me bringing maybe too much of subjective perspective, but for now this chinese kit is the best kit in the world for me, as it's only option to get the bike running again.
otherwise, if/when the future lets, still thinking to install normal ydis. it's one more reason for which i'm trying to keep the original airbox setup.

ok, some updates -
this new kit is 1.25cm shorter (filter-engine axis), so thinking to craft some aluminum adapter plate between engine and manifolds.
speaking of manifolds, using pair of right (bigger) intake manifolds of xt, one assigned on left with 180° flip.
also, as these carbs have shorter fitting ends towards the engine, had to cut 3mm from manifold lips. afterwards they join well.

on the airbox side, right (bigger) air duct fits. but had to modify left one - cut ~1cm on the carb side and with scalpel and sandpaper made more or less soft (curvy) transition inside.
then took raptor's air duct and cut ~4cm from it (also carb side).
afterwards fitted that cut part over xt's duct like sleeve.
appeared pretty tight. glued with gasket silicone.
offset is about 1 cm:
https://i.postimg.cc/QM5VDh1q/DSC-0000074.jpg

these carbs are taller and their both lower and higher ends are more bulky compared to xt's carbs. had to play with some cables to make the fitment easy.

main problem for now is the distance between diaphragm vent passages and bike frame. it's too close even without that adapter plate:
https://i.postimg.cc/6pFTFy23/DSC-0000073.jpg

seems it's possible to cut some of their length.

in the case of raptor, these vents are connected to air ducts separately.
does this setup of raptor affect the diaphragm response?
what if i connect them to just the atmosphere with some sort of filter (like it's in xt's case)?

as for the adapters, you could also make them from nylon, its fuel resistant and a bit more forgiving to mount than aluminum.


for the vents, you just need a simple rubber elbow, and route from the 2 tubes to somewhere clean. the carb does not constantly suck air from there, its just to allow free movement of the slides, so a filter is nice but not a must, its more of a venting.


yes, they could be shortened too.



something like this for example (not sure if this is the exact size you need, but to get the idea)


https://www.amazon.com/Dorman-Help-4...ef_=ast_sto_dp


Hope it all works for you.

nylon sounds nice and lighter. easier to craft as well.
that elbow setup is clear. main thing is knowing that it's not necessary to connect these vents to air duct/airbox.
as for filters at the end, i don't think about dedicated mushroom filters, rather some simpler solution to block dust.
thanks for good infos!

some short summary and couple questions
 

long story short for now, carbs are installed and bike runs.

making adapter plate, finally decided to stick with aluminum, as melting temperature of nylon felt somehow as not on the "peace of mind" distance from possible surface temperatures of the engine run by carbs yet-to-adjusted..
https://i.ibb.co/SnSn6JR/DSC-0000075.jpg
used some gasket silicone to mate head and this plate.

for diaphragm vents used hoses already shaped with 90° corners, something like this -
https://encrypted-tbn0.gstatic.com/i...1A0DA&usqp=CAU

cables. was lucky to find flexible steel tube with 6mm outer diameter.
cut threads, bent and pressed into the carb body. smaller (more bent) is for choke.
https://i.ibb.co/5r1yhYm/P1050197.jpg

more photos and complete story later, when jets, needles etc. will be finally chosen/adjusted.

having these questions for now:

1. what if using smaller hoses for diaphragm vents (attaching them by pressing inside the steel tubes on the body, rather putting from the outside)? will this reduction of diameter affect how diaphragms will work?

2. needle jets had this cylindrical rings attached, supported by jets:
https://i.ibb.co/WBdDdYw/P1050198.jpg
these rings have 4 holes on the sides and reach almost till the bottom of the bowl.
problem is that in the jet kit i've got all main jets have the base (where screwdriver goes) bigger than inner diameter of this ring. so had to take these ring away and attach jets directly to the needle jets. btw, just like in the case of original carbs.
what it the function of this ring? maybe it worth to find jets with smaller base to let these rings make their sense?

nice!


HOW does it run then?



1. as long as you have 2-3 mm free internal diameter, i think the tubes will be fine.


you can try riding the bike with them disconnected for a few minutes, nothing will happen, then put the tubes on and see if they make a negative impact on riding. again, they are just vents to atmosphere to balance pressure



2. guess those jet protectors are for ATV to maintain fuel around when off roading.... i would say not a problem to remove. again, you are on your own here, see how it works with/without



compliments on the persistence!

turboguzzi, thanks for the answers etc.

good thing is that bike starts easily, generally feels bit more powerful, compared not only to the last days of previous carbs.

things to solve for now are rich-ish mixture (overall) and possible lug/delay which could happen somewhere between 25-40% of throttle opening. currently manipulating with needle positions.
temperature keeps changing here pretty sharp day after day these times and feedback seems complicated.
hopefully will manage to test exhaust with the mixture gauge.

maybe before worrying about that jet protectors, will consider to check fuel level in the bowls. thing is that these carbs now are somehow inclined forward compared to their intended use (raptor), maybe 15-20°.

smaller diameter vent hoses could make removal/installation times bit easy. yes, it's still pretty hard process (especially installation), so every cubic cm of saved space matters a lot...

sounds like your jetting is close,
the 1st thing that you have to find is the main jet, leave the needles in original place and just try +/- 5 in the mains, find what works best,


only then move to needle height (if still needed)
these carbs can work ok with +/- 10 r even 15 degrees of tilt, so dont touch their fuel level for now. easy to mess that up

thanks again for a good advices, turboguzzi.
good to know that carbs are ok in the given setup.
let's see by which jetting i'll end up with...

raptor 660 carbs on xt600e
 

hi everyone
after >3000 kms with new carbs, seems it's already a time to share details and feedback.
on my high-mileage '02 xt600e, original (ydis) carbs became worn and damaged beyond repairability.
considering suggestions by more experienced members, prices, availability and so on, decided to replace damaged carbs with the ones from 660 raptor. although, bought not an oem kit but a chinese clone.
part of the plan was to keep the original airbox on my bike.
let's have a look on general diagram of raptor's carbs:
https://i.ibb.co/MfXPnZc/raptor-660-carb-kit.jpg

to compare air ducts and engine intake of xt and raptor, they're more or less the same.
on xt "left channel" (air duct & carb intake - carb output & intake manifold lip) is smaller, compared to the "right channel" (all these members are with bigger diameter).
raptor has (almost) symmetrical channels, with the sizes equal to xt's right, bigger channel.

now differences.

maybe the main point to consider (at least in my personal opinion) is how these carbs work: while xt's ydis setup is somehow a complex (but still nice) combination of slide and cv carbs, raptor has almost identical 2 cv carbs just joined together.
throttle: xt has dual cable setup, while raptor is run by single.
choke: xt (at least my generation) had a pull lever immediately on the carb body, while in the raptor's case it's cable operated.
hoses, vents etc.: raptor's carbs have them a few more and fuel delivery pipe is also with a bigger diameter (8mm as i recall).
dimensions: raptor's kit is heavier, overly taller and wider but shorter (longitudinally, along with intake axis) by 12mm.
partially this shortness is caused by where the intake manifold mating grooves start on raptor's carbs: they start ~3mm closer to the main body, resulting a shorter output lengths, i.e. these carbs don't go into the intake manifolds as deep as xt's carbs.

according to all these differences, here're the lists of modifications on bike and carbs separately.

mods on the bike:

• adapter plate, to compensate length - 10mm aluminum between the engine head and intake manifolds. basically, it needs two 30mm holes at the distance of 30 mm, with four 7mm holes for the bolts. plate is glued to the engine head with gasket silicone. in theory, the 8mm plate might also work, making removal/installation of carbs a bit easier but it may stretch air ducts more and create some risk of leak.
  https://i.ibb.co/SnSn6JR/DSC-0000075.jpg
  
• intake manifolds: raptor has asymmetric ports and moreover, manifolds are angled much more, but xt's manifolds work in this way - left one is not useful, instead another right (with bigger diameter) piece is needed. also, since these carbs don't go into the manifolds as deep as the original ydis, manifolds must be shortened - 3mm of the length is cut from the side of the carbs. there's still enough width left for proper band clips. for easier fit, a small (~1mm) tapered slope is cut inside manifold lips.
• air ducts: right one is suitable, left is again small. one option could be to replace it with another right duct, but due to current crazy prices for this part, bought raptor's air duct instead and cut the final few cm on it (carb side). then shortened (~10mm) xt's duct and combined (again silicone) it with the cut part from raptor's duct. luckily, that part from raptor's duct fits perfectly over xt's duct like a sleeve, and considering where to cut, it's possible to achieve a pretty smooth transition between these two rubbers.
  https://i.postimg.cc/QM5VDh1q/DSC-0000074.jpg
  
• throttle: one cable gets removed, assigned for the choke later.
• choke: found handlebar lever of some quad bike. it appeared pretty easy to attach below the left switch assembly with two screws and also easy to reach and operate by thumb.
  https://i.ibb.co/TckyGm2/choke-lever.jpg
  

mods on the carbs:

• steel tubes of diaphragm vents: they were almost touching the frame, so had to shorten both, now about 8mm is left. attached rubber hoses are with 90° bend immediately at the beginning to go away from the frame. ends of the vents are covered by pieces of breathable textile (yellow ones on the photos below) to make a dust barrier.
• cover plate (#15 on the diagram): had to remove it, as it was making installing the carbs almost impossible.
• main jet protectors (#23): removed them also, just because of the jet kit i had - heads were bigger and not fitting inside those rings.
• cable guides: these new carbs came with 2 of them, but their shape was not suitable. and they were pretty hard to bend properly, so found some softer steel tube, cut 6x1mm thread, bent as needed and pressed instead of old ones. one with 90° bend is for choke. long nuts are useful to adjust free play of cables.
  https://i.ibb.co/595mL0L/cable-guides.jpg
• idle mixture adjustment screws: when carbs are installed, it's nearly impossible to reach and adjust the one on the right. the only way seems to be the combination of good light, tiny concave mirror with a long handle and a small flat screwdriver bit attached to the gimbal ratchet. but even this wouldn't work if i had bit thicker fingers (and the engine hot enough). so special screws with long handles are highly recommended. the ones i've ordered later came without markings. markings are important not only for obvious reason but to be able to check that they don't move.
  https://i.ibb.co/9c8d0TK/adjustment-screws.jpg
  despite that these new screws came with stronger springs, i've made them a bit lighter by drilling their levers and after installation they're bound with a rubber in ∞ pattern.
  https://i.ibb.co/wBT0DCK/rubber-band.jpg

installation procedures:

removal/installing carbs on this bike has never been easy, especially with some earlier modifications around.
now with these generally bigger carbs, more hoses (and more about to come after waterproofing with t-joints) and cable guides pointing outside, it's a real challenge. after lots of wrestling in the past and now, i found this way best:
https://i.ibb.co/1bYmTgn/removal.jpg

move the airbox as further back as possible, remove the ignition coil, lift or disconnect cables around, detach and lower the rear brake fluid container and remove the right intake manifold, then take carbs out from the right side. when assembling, carbs go back from the same side. first i make sure that both air ducts fit well, then, while the airbox is still back, stick in right intake manifold and tighten the bolts. then it's time to push airbox&carbs forward, twist carbs back and forth until they will go all the way into the manifolds.
in this easy-to-write/read turmoil, every step making the process even slightly easier matters a lot - like each free cubic cm, lubed lips, all band clips in proper positions etc. etc..
although, along with all these dark stuff there's at least one noteworthy benefit: both needles are adjustable without the removal of the carbs, just considering that uncapped carbs don't collect any dust from the frame or cables around.
that's how installed carbs look like from the sides:
https://i.ibb.co/WGY3K6w/carb-l.jpg

https://i.ibb.co/w62CMdH/carb-r.jpg

when making cable adapters, another important point to consider is that space around them is pretty cramped by the body of the carbs itself, engine and fuel tap:
https://i.ibb.co/SdG1yfF/cramped.jpg

now about jetting.
current conditions are following:
oem airbox without snorkel, k&n washable air filter; oem headers with straight aftermarket muffler.
80% of riding is happening at 0-10°c (dry climate), and at 400-1000m altitude.
idle screw is about 3 turns in after touching the plate, rising butterflies maybe 1mm.
idle jets are unchanged, #22.5.
idle mixture screws are at 2.25 turns out.
starter jet (for choke) is #80.
main jets are #140.
jet needles have 6 steps and they're in the second position from below, i.e. raised almost all the way up.

summary and conclusions:
with this setup, the bike starts easily and feels a bit more powerful. fuel consumption is either the same (5.5l/100km) or slightly more.
throttle response is not linear, feels more steep in the beginning and if the throttle is squeezed fast enough, could transform into the step (somewhere around 1/4 of opening). this could happen at sharp deceleration as well, so the solution for now is softening this step with slight clutch input. maybe this is solvable with better tuning.
the only actual problem i had with these cheap carbs is seemingly the shaft moving throttle butterflies could develop some friction-like resistance above 75% of throttle opening (where there's least movement statistically). it still moves but with some unsmooth feelings. cleaning the carbs from inside/outside solves this problem, but it could appear after 1000 or so kms. anyways, will have a closer look on next removal, maybe will attempt to split the carbs as well. only clue for now is that despite being behind the engine, since that protector plate (#15) is removed, the shaft mechanism is more exposed...
generally, i'm pretty happy with this conversion. after ordering these carbs and before actually trying them, i was thinking about them as more or less temporary solution, with a mindset to keep an eye on the web to find some decent original ydis carbs. for now it's changed and seems i'll be happy keeping them as far as they'll be happy doing their job )

of course, i'd like to thank all the forum members helping and supporting me along the way with their advices, infos and ideas, together with people making this forum possible.

p.s. some random fun before and after )
https://i.ibb.co/92Yv384/miau.jpg https://i.ibb.co/MVQJK0d/P1050219.jpg

Consumption is really high, mine is 3,7L/100km.

well, guess it's partially caused by riding style as well - as remember, used to have <4l/100 km when following a car in smooth/slowish pace.

Yeh offc but i never had that much change even with harder riding. Can you do a test in 80kmh steady riding and see what its at next time you are on a trip?

yep, would be interesting how will the consumption be on this steady mode. maybe will try on the occasion in flatter side of the country on calm weather.

Bravo! nice wrap up, kudos to you for taking on the job in a place where there is much less technical support.


I wouldn't loose sleep over 5,5L/100km,


According to data of 32 persons (23 + 9), its within normal.


https://www.fuelly.com/motorcycle/yamaha/xt600e


https://www.fuelly.com/motorcycle/yamaha/xt600z_tenere


just choose L/100 units.


keep up the good work!

thanks for the reply, and links give a clear picture of what i've heard/remembered randomly.
guess this forum at least somehow compensates me the lack of technical support :mchappy:

Riding in city with hills and a little choke start its approx 0,4, the 0,37 was at 80km trip started with full tank, filled up at 80km and going between 60-80kmh steady not only flat riding. For the link with people having 0,38mpg i recomend looking for leaks or overhaul carb/adjust valves and check comp, never had on any of mine XT 43/3tb/4pt even with hard riding and 2 on bike it was steady 0,5l.

in my experience, the further I've been in a single tank is this https://maps.app.goo.gl/MJgA7HRudu3K6mC39

it's 165 km and I was thrushing it . my xt though has a wiseco flat 98 mm piston and it's 636 cc and has a second stage cam and most importantly it has a signle 39mm Fcr keihin carb. That makes it about 9L/100
i took it there because there is one of the best xt mechanics in Greece located there and my bike is there a couple of months...
i will upload later on the things i asked him to do .

nick, open a new thread, your bike is a very different story from N67's bike....


in any case, 9L/100km sounds waaay too much.... something in the way your carb/ignition/engine are setup is surely not optimized. quite hard to give you advice without ever seeing.



go to these links, switch units to L/100km just to see how bad is your case.

https://www.fuelly.com/motorcycle/yamaha/xt600e

https://www.fuelly.com/motorcycle/yamaha/xt600z_tenere



And the carb, cam and piston dont explain this, very often a tuned bike gives better milleage than stock due to better efficiency.


open a new thread and we can continue there.