Hey all, searched but not a single hit on the xt600sc (California emissions model). Surely I'm not the only one?

I'm resurrecting a 1986 xt600sc, parked with fuel in the system over 20 years ago. I'm a bit rusty myself when it comes to carb work but Carb cleaner and patience seem to be winning on the hard parts. All of the o-rings and gaskets pretty much disintegrated and need replacing. I gather oem is the best (or only) source for these now?

Also, the air intake and exhaust system are stock, but the original charcoal emissions canister had been removed and some of the carb ports / hoses capped off. I'd like to get this bike running without the emissions junk if possible since I'll be using it off road with a Clarke tank (petcock only, no emissions outlet bung for the tank to canister pipe).

Curious what effect if any omitting the emissions equipment will have on jetting, etc.? I've seen references that the standard xt600 primary main jet was a #130, but the one I pulled was #125? I wonder if the sc model carb came with it or it was installed later, possibly to compensate for the lack of charcoal canister... anybody?

I imagine this isn't the first time an xt600sc lost it's canister, so perhaps someone has a suggestion on which primary and secondary main or needle jets, clip position etc. will run best on this carb with the emissions bypassed, and whether simply capping off all unused carb ports is standard procedure or if any need to be vented to atmosphere?

Thanks much, forum has been a great help already!

:confused1: Hmmm

Maybe I really am the only one with a sc model, or is it the -dreaded- new poster plague? I sure hope not, I could use a a bit of help here and this is a technical forum right?

1.) In all of the online parts fiche exploded views I've found to date (ex. attached), the primary main jet (fiche part 7) is noted as #130, and secondary main jet (fiche part 59) is noted as #125.

Clymers M416 - Carb Specs p. 271, show primary main jet #125 and secondary main jet as #130 (which, for those in need of hand holding, would be the exact opposite). Clearly, one is wrong.

As mentioned earlier, I removed an existing #125 primary main jet and #130 secondary main jet during tear down. That leads me to believe Clymer's specs are correct however, adding to the mystery, the bike also came with a #130 primary main jet in the box 'o parts.

I'd like to rebuild the carb to factory specs, can someone confirm the correct oem primary and secondary main jet sizes please.

2.) Soliciting input on this but suspect removing the emissions system will not effect a/f mix sufficiently to require either primary or secondary main or needle jet changes. Correct?

However, if I add a UniFilter, I've seen posts suggesting that a larger secondary main jet was necessary due to increased air flow. I find that kinda hard to believe, assuming all else is stock, since many say these bikes are set factory rich to begin with.

So whadda ya think or, better yet, whats your actual experience? Other than the UniFilter, I'd be sticking with the stock oem air/ exhaust systems for now and riding mostly at 500-1000' ASL.

3.) And today's -best- U.S. source for in-stock carb parts and prices is? Being a small business owner myself I generally prefer to support my local compadres, however, the Yammy shop is the only one around and chooses to bend customers over at the waist each time they walk thru his door for parts. Plus, I refuse to go back after these idjiots sent one of my new bikes home with several loose case bolts after it's initial service and it puked all 2+ quarts of oil on the garage floor.

I've been pricing the carb parts at boats.net (many motorcycle model year parts fiches available) to get oem p/n's and an idea of what the rebuild will cost, but would like to hear your happy referrals.

4.) Has any generous soul compiled a size guide for compatibility of O-rings in the carb? Since an assortment of 500 metric nitrile O-rings goes for about $5.00, I'd prefer not to buy $80 worth of expensive needle sets when I don't need them just to get the O-rings. Mine are so disintegrated I have nothing left to measure.

Specifically, any idea what size are used to replace O-rings on the following fiche parts: 10, 16, 25 and 54.

5.) Thankfully, the only other difficulties I've run into are:

a) Clymers p. 244: Secondary Carburetor Disassembly Step 17 says "On all models, the pilot air screw is fixed in a blind housing (Figure 38) and removal is not recommended as the housing plug must be removed." Why this isn't under Primary Carb Disassembly, who knows.

Regardless, there was no plug on mine so naturally I removed the pilot for cleaning/inspection. It was so gummed up with varnish and rubber I could barely back it out, never mind first turning it in to determine the original position setting.

I've seen posts that say oem position setting is (2) turns out, and I've seen posts that say (3) turns out. Can anyone confirm which setting is correct please?

b) Fiche part 16 (the 3-pc pilot screw set) shows a pilot screw, O-ring and, I presume, a removable needle seat which I can't seem to work it loose. How the heck do I get it out without buggering it all to hell?

Your turn.
Thanks for any comments

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Maybe I really am the only one with a sc model, or is it the -dreaded- new poster plague? I sure hope not, I could use a a bit of help here and this is a technical forum right?

1.) In all of the online parts fiche exploded views I've found to date (ex. attached), the primary main jet (fiche part 7) is noted as #130, and secondary main jet (fiche part 59) is noted as #125.

Clymers M416 - Carb Specs p. 271, show primary main jet #125 and secondary main jet as #130 (which, for those in need of hand holding, would be the exact opposite). Clearly, one is wrong.

As mentioned earlier, I removed an existing #125 primary main jet and #130 secondary main jet during tear down. That leads me to believe Clymer's specs are correct however, adding to the mystery, the bike also came with a #130 primary main jet in the box 'o parts.

I'd like to rebuild the carb to factory specs, can someone confirm the correct oem primary and secondary main jet sizes please.

*** Do not know: I do not have the factory specs for the California type. In Europe the original jets were prim / secon 130 / 125.
Just try and see what runs best. I bet on the 130 / 125.
Remark: why does everybody always starts f*cking around with the jets? Unless really chosen wrongly it is the needle positions that really matter for everything but full throttle operation.

2.) Soliciting input on this but suspect removing the emissions system will not effect a/f mix sufficiently to require either primary or secondary main or needle jet changes. Correct?

*** Do not know, but likely.

However, if I add a UniFilter, I've seen posts suggesting that a larger secondary main jet was necessary due to increased air flow. I find that kinda hard to believe, assuming all else is stock, since many say these bikes are set factory rich to begin with.

So whadda ya think or, better yet, whats your actual experience? Other than the UniFilter, I'd be sticking with the stock oem air/ exhaust systems for now and riding mostly at 500-1000' ASL.

*** Opening up the air intake will indeed decrease resistance, increase airflow. With the bikes I have (3AJ, TT600 '86) no need at all to re-jet, they just run better. Try ...

3.) And today's -best- U.S. source for in-stock carb parts and prices is? Being a small business owner myself I generally prefer to support my local compadres, however, the Yammy shop is the only one around and chooses to bend customers over at the waist each time they walk thru his door for parts. Plus, I refuse to go back after these idjiots sent one of my new bikes home with several loose case bolts after it's initial service and it puked all 2+ quarts of oil on the garage floor.

I've been pricing the carb parts at boats.net (many motorcycle model year parts fiches available) to get oem p/n's and an idea of what the rebuild will cost, but would like to hear your happy referrals.

4.) Has any generous soul compiled a size guide for compatibility of O-rings in the carb? Since an assortment of 500 metric nitrile O-rings goes for about $5.00, I'd prefer not to buy $80 worth of expensive needle sets when I don't need them just to get the O-rings. Mine are so disintegrated I have nothing left to measure.

Specifically, any idea what size are used to replace O-rings on the following fiche parts: 10, 16, 25 and 54.

** I do not have one. If your 'nitrile' is petrol resistant, that seems to be a low risk bet - try it. Two exceptions: the special O-ring around the choke system pipe (mating face carb bowl - carb), I'd buy OEM, and the gasket for the float bowl. Only the original Yamaha ones are good.

5.) Thankfully, the only other difficulties I've run into are:

a) Clymers p. 244: Secondary Carburetor Disassembly Step 17 says "On all models, the pilot air screw is fixed in a blind housing (Figure 38) and removal is not recommended as the housing plug must be removed." Why this isn't under Primary Carb Disassembly, who knows.

Regardless, there was no plug on mine so naturally I removed the pilot for cleaning/inspection. It was so gummed up with varnish and rubber I could barely back it out, never mind first turning it in to determine the original position setting.

I've seen posts that say oem position setting is (2) turns out, and I've seen posts that say (3) turns out. Can anyone confirm which setting is correct please?

*** Seek and ye shall find: just get your bike started and set it as per instructions in other posts. Start with 2,5 turns out.

b) Fiche part 16 (the 3-pc pilot screw set) shows a pilot screw, O-ring and, I presume, a removable needle seat which I can't seem to work it loose. How the heck do I get it out without buggering it all to hell?

*** No seat there, in the set are supposed to be a needle, a spring and an O-ring. If you order the set from Yam, they forget the O-ring.

Your turn.
Thanks for any comments

Good luck
Auke

__________________
Auke
http://aukemarieke.blogspot.com

Auke-

Thank you, your reply was helpful and appreciated... even if you did just throw a third jet combination into the mix LOL!

I agree with you 100% about jetting and, of course, there's no substitute for actual hands-on test. That's why I'm trying to confirm oem so I can bring it back to spec and start from there. And yeah, sorry, lotsa questions even after searching pretty deep. But, lets face it, carb removal and jetting on this bike is just enough of a P.I.T.A. to make shootin' from the hip a frustratingly long process. If it can be avoided with a little pre-planning, I'm grateful for any help, no desire to reinvent the wheel.

Anyhoo, here's what I've decided to do...

1.) Proceed under the assumption that removal of the CA emmissions system is a non-event when it comes to main and needle jetting. Cap off the carb vacuum port on the left side of the carb just ahead of the left overflow port where vapors from the charcoal canister were routed into. Keep the bottom bowl rain line routed thru the 'S' trap bracket and both overflow pipes as is. Reuse the stock fuel tank with the emissions roll-over assembly outlet on the tank plugged or replace with a Clarke plastic 'petcock only' tank. Replace the existing vent-free tank cap with a vented cap.

2.) Because a) the 'extra' 130 primary main jet looks to be unused; b) I don't have a 125 secondary main jet, and; c) due to the folks at EPA it wouldn't surprise me if the oem U.S. spec primary main was jetted leaner (particularly the CA emissions model) than it's European cousin, I'm going to start with the assumption the current configuration I have is correct, ie., 125 primary /130 secondary mains.

3.) I originally was going to 'split the difference' and use 2-1/2 turns out on the pilot, but since have seen a couple more votes for 2 to 2-1/2. So, what the heck, I'll start with 2-1/4 out, don't think 1/4 turn either way is going to be a big deal anyway.

4.) Because a) I will be opening up the air intake a tad with a new UniFlow filter, and; b) you all seem to be running just fine with a larger primary main jet, I'm simply going to lower the clip on my primary needle to one notch from the top. Basically, that will be the only change from what I believe the U.S. sc model spec to be. Maybe a tad rich but, hopefully, not too much to have to rip it off and try again, and a tiny safety margin for adding that less restrictive silencer in the near future. Make sense?

5.) My jets, needles and seats cleaned up fine. Instead of coughing up for the mega-expensive needle sets, I'm just going to buy the $5 metric O-ring assortment and $95 of . Viton O-rings would probably be best, but nitrile has excellent fuel and petroleum qualities and also sufficient alcohol resistance for the 10% ethanol blended gas on this side of the pond. Much easier to find in metric size here, and cheaper too. If it works great, if not I can take the edge off the learning curve and a bigger parts bill with those cold s right quick!

6.) I wondered why that one particular O-ring (fiche part 25) was showing on the parts list as 2-3x the cost of the other O-rings in the carb. I'll take your advice, consider it critical and add it to my oem parts order. If it saves having to muck around in there again it's money well spent, thanks. Oh yeah, I was lucky enough to find a float bowl and oil filter gasket in my leftover parts bin, woohoo!

7.) -slapping my forehead- A spring? Duh, silly me! Got it right here in the ziplock baggie!

Again, all input including constructive criticism is appreciated. I'm not totally new at this but recognize there are a bunch here with a lot more experience than I. If anything in the plan above sound like trouble, I hope someone will have the stones to sound off.

Thanks!

Oops, forgot to ask:

In addition to the outlet providing fuel supply to the secondary and the overflow/drain pipe outlet, the bowl on my carb has another downward pointing outlet that is factory blocked. Is that for something not applicable on the sc model? Also, just above where that would come thru the bowl is a small orifice. Where does the orifice lead to please, it's not clear in the fiche or Clymers what that's all about.

Thanks, again.

I know of two outlets on the float bowl - one to the secondary jet (hose connection) pointing to the right with carb installed, one for draining of fuel (hose connection), pointing downwards. This last one you are talking about? - It is connected to the overflow pipe and to the hole that is closed off by the drain screw at the bottom of the bowl.
The orifice leads to the drain connection.

See picture: www.xt600.de PrimärVergaser - Schwimmerkammer oben
26 is the overflow pipe. To the right you see the orifice leading to the drain connection.
They blocked it in California to avoid fuel being spilled?

28 provides fuel to the choke.

Auke

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Auke
http://aukemarieke.blogspot.com

My bowl is different. I have the same secondary outlet (29), drain outlet (27) and overflow pipe (26) as shown in the pic. However, the CA emissions model uses a thumb operated enricher as opposed to a choke. As a result, the internally cast (choke tube?) cavity (#28) is totally blocked.

Unlike the pic, there are no orifices or passageways into this cavity on my carb. The orifice I was referring to is the one located right at the base of the tube, and I suspect allows fuel to flow from the bowl into the tube. Mine looks like the pic, ie., has a hole, but doesn't seem to be open. Couldn't get air to pass and was concerned it may be gunked up rather than factory blocked.

The downward pointing 'mystery nipple' is located under the circular cast mark between the orifice at the base of the tube and the bowl sump. Internally mine looks just like the pic, but external is a full length hollow nipple (similar to the drain/overflow outlet nipple), but it is factory blocked.

Does your non-CA carb have this? Wondering why they put it here if it is unused on both model carbs? In Clymers, reference is made to connecting the dealer float level tool, ie., plastic tubing. My guess is that the port is drilled and tubing connected to this nipple for such use.

Sorry, I do not really get it .. pls look at the following picture and explain again.
www.xt600.de PrimärVergaser - Schwimmerkammer links

Auke

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pic 1: Factory blocked outlet nipple - float level tool test port?

pic 2: Factory blocked orifice - inlet to choke tube on non-SC models?

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How you choke works then, is a mystery to me, or did you already describe it somewhere?

Seems to me that the only thing you need to 'De-Californise' your carb is the bowl - but if it works, don't fix it.

Auke

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Auke
http://aukemarieke.blogspot.com

Instead of using a choke to restrict air, the SC model uses an enricher jet control on the primary carb to provide more fuel for cold starting. The enricher is cable operated by a thumb lever on the left hand grip but, even after having the carb apart, it's still not entirely clear to me where the fuel pickup for the enricher in the carb is.

Good news is I was able to get the carb back together using O-rings on hand. The drain screw is not leaking and if there is any problem with the 'critical' choke tube O-ring I stuffed in there, it's not making itself apparent at the moment either. I blocked the roll-over valve outlet on the tank and cleaned the petcock assembly, though that still weeps slightly. Looks like I'm going to get lucky... sum total of oem parts ordered: petcock dial gasket seal, drain screw w/ O-ring and choke tub O-ring. Add the D.I.Y. air filter element foam and I may have spent a whopping $20!

By now it was after 1am but I was soooo close I had to kick it. So, after plumbing a fuel filter in line and topping up the oil, I put my boot on and gave it a stomp. Well, five to be exact before the som'obetch fired and came to life for the first time in 15+ years (1993)! Smoked like a old 2-stroke for a good bit but settled down and sounded so good after about 10 mins. I took a short ride up the road and back. No popping or spitting from the primary side, waiting till after an oil flush to hammer the throttle.

I think it's safe to say... WE'RE BAAAAAACK!!!!!!!

Beauty awakened ...

The standard 'choke' setup on the XT carb is a separate 'carb' arrangement inside the carburettor. There is a plunger on the LH side of the carb that is either operated by a knob directly on the carb or a cable from the handle bar.

Still wondering how that works in California?

Auke

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