The reason why the gears slip is wear between the 2nd and 5th gear pinions on the lay shaft, the 5th gear has dogs/ studs which connect and lock into the second gear, if these studs are worn or rounded or the slots in the 2nd gear are worn this will allow the gears to slip out. One fix for this is to move the gears closer together by removing a spacer to stop them slipping which is what I’ve started looking at.
You’ll need hex keys, a mallet, some emery cloth and a few spanners – mainly to get extra leverage on the hex bolts, unless you’ve got decent ratchet handles etc… You may also need some silicon gasket sealant or new gaskets if like mine your’s have torn.
Get the bike up on a lift or paddock stands and drain the oil before proceeding… you may also want to remove the exhaust section if using a lift.
Step 1
On the left hand side of the bike we need to remove the casing. First remove the clutch cable, gear shifter and foot peg.
Step 2
Remove the 3 bolts for the timing case cover and remove the cover – its the bit with Yamaha written on it. Inside there are 3 screws that hold on the timing plate, you need to mark their positions – take a photo and use a knife to scratch in a mark for each one and remove each one. Next remove the center bolt, hold the outer nut (gold) and loosen the center bolt (silver) to remove it.
Now thats done you can either completely remove the timing plate or just let it hang from the wire. Now we can work around the rest of the casing removing the bolts. Start at one point and work clockwise around keeping the screws in order of removal so you can make sure you replace them as you found them.
Step 3
If its been a while since this casing was removed its going to be really stiff, time to call in Senior Tappy! Basically get something to protect the casing, e.g folded tea towel etc.. and with that between the casing and a hammer/mallet hit it a few times to loosen the seal. The casing then should come loose. Remove the casing, watch out for spindles and cogs – there’ll only be one loose.
Step 4
Now we can remove the layshaft bearing housing cover which will give us access to the area we need to work on. There are 4 screws to this cover and it sits behind the gear shift lever. Its going to be really stiff to remove so you’ll need Senior Tappy again to shake/tap it loose. It will take a lot of work but persist it will free up just keep wriggling it to get it over the gear shift lever.
Step 5
Ok, now if you look inside you should see a cog. That’s 2nd gear on the layshaft which apparently is what causes the issues of the gears popping. So we’ll remove the circlip and shim in front of the cog, for the circlip some needlenose pliers should do the job.
Step 6
Here’s the worst bit – removing the cog. Now you can take the sump cover from the bottom of the bike but its a hassle and as long as we’re only dealing with 2nd gear here we can get away with out needing to do this. First get some emery cloth and lightly sand down the tops of the 6 ridges that were in front of the shim and circlip. We only want to remove the dirt and crud there so the cog will slip off. To get this cog in and out you’re going to need brute force and a few small hex keys. You should be able to get the short length of the hex key behind the cog by sliding it down the left hand side of the gear. With this in place get some pliers and get a really good grip on the hex key and begin to pull the cog out – it should give. It will take some time but keep at it – best to have 2 people taking turns. If you take the sump cover off you can probably push the gear off rather than pull it this way but its more effort really and my XS750 doesn’t have a centre stand and its on a jack.
Step 7
Remove the shim that was behind the gear pinion – it may be attached to the rear of the gear. Now reassemble to gears and casing leaving out this shim. With this spacer gone 2nd and 5th gear should lock together better and prevent the gears slipping out, you may want to add the shim you removed to the front of the pinion to help push it closer to the 5th.
Thats it! (I hope)…
Now if all of this doesn’t work there are a couple of extra options, you can get replacement gears off of the XS650 as its chain driven and the pinions won’t be so worn, or get new replacement pattern parts. You can also machine your existing gears to remove the rounding on the dogs of the 5th gear to get a better fit to help stop slipping. Also you can look at the shift fork on the right hand side of the bike.
I’ll update this post if I have to do anything else to remedy the problem.
Possibly related?...
well did it work ive just aquired an xs750 with this problem
Yep, it did work – not had the problem since
Hey Larry,
I recently acquired a 78 triple from my brother with a similar problem. He said that he only got it to go into 2nd gear a couple of times, otherwise he would just skip 2nd altogether and go straight to 3rd.
You mentioned your triple “popping out” of second but, did you ever NOT have it go into second gear at all? I’m wondering if I could apply this fix to my bike or if it could be something else.
Any help would greatly be appreciated.
best thing is to check for wear on the layshaft – you’ll need to split the engine to get at properly, but you’re looking for any of the dogs/ spurs being worn on the sliding gears which will casue the issue – also look at the gear selector drum and forks as there may be wear there
Did you need to replace any of the gaskets and o-rings you removed (the crankcase cover gasket and the bearing housing O ring I think)? If so, know where to get them for this bike?
had to replace the crankcase gaskets, which I did with instant gasket while testing if it fixed the problem – at the moment this is still the case while working on the electrics but you can get gasket sets from wemoto or ebay