If you can put the newest version in I would go that route, otherwise it may or may not eventually be an issue. If I was planning to do a lot of long hours on one I'd send it in to be coated with something like our endmills and metal cutting tools get, AlTin, TiN, ect... Like this Surface Solutions - Your Source for Physical Vapor Deposition (PVD) Coatings. The guy we send to quoted me around $20-$30 to do a pair of gears. Maybe it wouldn't work, maybe it would , Honda and some others do it to the small connecting rod end instead of a bearing and it holds up great, little different application though.

Best solution dont use the 5th gear, change sprockets to get a little higher speed on 4th.

Hi and thanks for the contributions.

I looked at 5 items that could impact 5th gear life and where/when they were introduced:

1, new better gears, 1986 1VJ and both in 1988 on 3AJ, prefix 2JT.
2, better lubrication, greater volume oil pump, 1VJ, 3AJ. Same dates.
3, better lubrication, dedicated oil line. 1988 parts list has that pipe.
4, changed primary ratios reducing torque load. Again 1988 3AJ.

None of the above seem to have made much difference.

Then there is a gap in my info until 2001 and the 4PT list

5, new better gears, wider. Prefix 3YF As Bobmech posts; problem solved.

Good Grief, i've just googled 3YF and the gap is filled. 3YF is 660. These gears have been used in 600s since 1996.

I feel a bit silly. Didn't think Yamaha would carry on with a transmission that had been a failure since 1983.

So top tip is, if you have been hording 5th gears... toss them out and get the latest 660 ones.

Seriously, there must be a way to fit these reliably. I found one could machine 2nd gear narrower, only the centre of it, not teeth. But the wider 3Y 5th gear which engages 2nd, is very close. ie. 2nd neutral is tenuous. I made a small mod to the ramp on drum to compensate. We have not run that engine yet!

We need to look inside a late 600 gearbox. Anyone?

p

I've got a TT600R from 2001 (build from 97-02). Model code is 5CH.

I went to motorcycle spare parts.eu and the 5th gear part code is 3YP171510100. Apparently its a 24 tooth pinion.

Does anyone know which XT its from?

My TT has the clutch routing on the left side of the engine and seems to be assembled from the Yamaha parts bin...cylinder from a 3TB, crank case assemble from a 4PT, etc.

EDIT: I dont know if it's a 24 tooth pinion, it just says "GEAR 5TH PINION (24T)".

3YP does not immediately reveal itself. 3YF i think is the 1st XT660, air cooled 5 valve engine.

Considering how Yamaha use prefixes for basic models and then small changes to that prefix for certain countries, 3YP is probably just a variation of 3TF.
BUT; a new part takes on the prefix of the bike where it is 1st used.
Or that is what we are told. So you may find that there is a significant difference.

Your gear does not have the 5CH prefix of the bike, so was used on a 3TP bike. It has the correct middle part of number to be a 5th pinion. All 5th pinions anywhere are XXX 17151 XX XX. And it has 24 teeth. The last 2 sets of digits can be important. The 2nd last may indicate a mod of significance.
The very last 2 often omitted, usually a colour.

The best resource i have found: cmsnl has a discrption: Yamaha - frequently asked questions

Interesting to see that the late 4PT engines still used the old 34K 2nd gear. So the space was created another way.

I picked up my new 5th gears from my friendly Yamaha dealer yesterday
Going to be a few days before i can get to work on the bike.

best,
p

I checked the link...it seems that my 5th gear has one design change.

Thanks for the link.

Hi PropTP, et al,
I reveal my lack of knowledge Your bike is a TT, i have almost no docs on them.
Fact is there is just too much, i can't / don't want to go there. Rather we should be able to find our way around the bikes we own.

To that end i'll correct a few of my mistakes and just start the 5th gear mod. I think that the whole job should have a dedicated thread, and i'll take a while to get that done. Very busy right now.

The 5 changes i talked about: the change in transmission ratio would have had a beneficial effect on life. Engineering principles. The 2JT gears used from 3AJ right up to the 660 3YF probably did too.

But the final mod, which now looks likely to have been most effective, was the adoption of 660 gears.

The clutch cable move had nothing to do with it, happened to be changed for 660 and adopted for 600. Seems logical.

I missed that. I found it difficult to make that connection because i never found a part list 1st 660.

Looking at the 600E part lists available right here, both 3TB and 4PT in various markets it is beyond us to find each change. The 4PT transmission has many 3YF parts. The entire case is 4PT, as is the shift drum and shift forks.

So my mod will be to a 2KF, very similar to later 3TBs and 600s sold in USA.

This has been done before. I have no doubt David Lambeth has been doing something like this for a long time. Probably perfected it, with all the experience he has.

Here, if i get it right, are photos of the gears. Plain to see they are wider, 11.2 mm to 14mm for pinion.

p

Attached Thumbnails

 

 

I am a bit confused about the oil pump. The parts list I looked at showed the 3AJ pump used in the 84,85,86 motor a 1VJ in the 89 motor and the 90,91 shows the 3AJ again. If the oil volume increased as said why is the pump the same in the 90 as the 85? The odd man out is the 89 with the 1VJ. Even though the 3AJ is the same the part number differs several times. 86-88 3AJ-99999-01858-00, 90 3AJ is 99999-02120-00, and the 89 and 91 3AJ shows 99999-02117-00. WTF! THUMPTHUMP

Partzilla shows a complete number change in '90-'95 ,'84 to '88 , and '89. Comes out right with the new pumps in '90, don't know what the difference is in the '89, I'd have to look at mine when I replace it . The 3AJ designation is just Yamahas letters for the oil pump on Xt's , or something like that. Wherever you got those numbers from is mislabeled.

On-line parts lists are confusing. It seems they only deal in models sold in US and are unaware of rest of world and change points we know by model and year.

Example: the big end crank-pin changed diameter by 1 mm somewhere between 34L and 2KF and i bought the wrong pin, 44 mm instead of 45 mm.
But how can i blame Partzilla when they appear to have no idea what a 34L or a 2KF is.

US seem to only ever have got the 43F right up to 1990. Correct me please, but some changes must have filtered thru' to those bikes, just no mention other an alphabetic letter applied to years, while the rest of us use a calendar.

I no longer go to on-line if i don't already have the part number from a Yamaha part list. It is now no longer difficult to find these, some are here and Mezo has a bunch over on his Tenere site.

BTW, this number 99999-02117-00 was used earlier to identify probably the 3AJ pump maybe as a kit with gasket and o rings. Yes, confusing.

But here is a short reasonably accurate explanation of oil history from the guru himself, enjoy:

XT Klaus cont:
anyway, since very long time yamaha doesn't sell 34L oil pumps anymore.
the only oil pumps available are the 1VJ pump and the 3AJ pump.
the feed side rotor thickness and hence the hauling capacity has developed from 4 mm (34L) to 6 mm (1VJ) to 8 mm (3AJ).
scavenger side rotor thickness is always 18 mm.
every pump is coded with 5Y1 on the bottom and a) no code (34L) b) 1VJ c) 3AJ on top.
there are also three different shafts:
34L: one groove (for circlip)
1VJ: two grooves
3AJ: three grooves
34L shaft and 1VJ shaft have equal length, only the drive pin hole position is different (because different thickness of rotor). therefore both pumps use the same sprocket.
3AJ shaft is longer and therefore requires a different sprocket (with code 3AJ).
yamaha advises to use the 1VJ pump for the following models: 34L, 55W, 43F, 1VJ, 2KF, 2NF, 59X(TT600).
3AJ pump should be used in 3AJ, 3TB, 4PT, DJ02 (generally every xt600 model since 1989 (tenere) resp. 1990 and also the later tt600 models).
nevertheless it is possible to mount the 3AJ pump in a 34L engine.
i would use the 1VJ pump for a 34L.
beside the pump you need two new o-rings and a paper gasket (to be mount between pump and housing). if you choose the 3AJ pump you need also the 3AJ sprocket. And 3 longer bolts 35mm.
XT Klaus

Give that man a Bells

p

Ya, the US only got 2 models and they didn't go in corresponding order as everyone else. I think ours are a mix of 34L & 43F's and 2kf & 3TB.

The 3aj pump fits fine in the 43F's that Yamaha advises against, maybe because the gear needs to be flipped over. All our older pumps have 1VJ on them with a 3AJ marked gear(confused yet?), at least all the motors I've had here. Like I said we got a mixed bag of parts, but not enough models.

I am trying to get a used high volume pump off ebay. I have to use the pictures to ID the pump with the higher volume. I do not really want to have to trust the year they post as the gospel. Any 89 or 90 pump would be the high volume pump? THUMPTHUMP

Or newer than that 3TB & 4PT`s pump & i think its in the SRX600 as well & even the 660`s use it.

As long as you can see 3AJ on there is the higher flow pump.



Mezo.

An '89 will not be the high volume one from a US model anyways, it has to be from '90-'95, the Estart models.

Mezo, I've found the 660 ones(at least the quad motor) have one mount bolt that is off by a couple mm,When I tried one in my 600 and threaded 2 of the three in and assumed the third was fine also so quit fitting it , the third can be used but needs to be slotted. I wanted to update that info. Otherwise everything is identical. It was my mistake for not trying that third bolt also.

Also note that there is a middle volume pump, 1VJ , that has more volume than the 34's but not as much as the 3AJ , it has the letters 1VJ and is in '88-'89 at least maybe earlier, i'm not sure,
The right is the 34L original pump , left is the middle volume,


Note the 2mm thicker pump, the 3AJ pump is another 2 mm thicker yet.

The lettering refers to the Tenere model codes, 1VJ (1986/1987) then the Tenere 3AJ 1988,89 & 90) but they worked well so they used the same pump in all XT`s from then on in, 3TB 4P using Tenere model codes.

Al i know is the 3AJ pump is 50% more oil flow than your standard earlier pumps, i never knew about the 1VJ pump to be honest but interesting none the less.

Geoff took a pic of the 34L versus the 3AJ.



Mezo.