Hello, I am new member from Appling, Georgia. USA. I have been riding off-road my whole life, at age 47 , the trials bug has bitten. I now own two sherpa t 350 model 92s' and have competed in three events.

My first sherpa had engine trouble when I bought it. The second one has been flawless. It is the first one I need help with.

The engine ran very poorly when I purchased it. Timing was off and it was pushing oil out of the clutch side. I replaced crank seals, points, condenser, timing chain tensioner, and re jetted the mikuni 28. It ran well, but wanted to rev, after it warmed up. I have since done a top end and still have the revving problem. I have sprayed carb cleaner all over trying to find the culprit. Have tried another carb too. Plug is a good brown color. Could it be burning transmission oil?

Any advice would be appreciated.

Thank you,

Tripp

When replacing the crankshaft seals did you replace the o-rings aswell?

When it was "pushing oil out the clutch side", where was it coming out?

If the clutch oil is getting burned, oil will disappear, so you can check for that

It's possible to have an air leak via the gasket joint between the crankcase halves, either via the gearbox or direct from the atmosphere. Again you can check for oil loss from the gearbox.

If you have a spigot mount carby, the hose between the carby and cylinder may be cracked

Replaced the o ring on the clutch side. There was not an o ring on the magneto side, just 2 seals and a paper gasket. Not sure if all models had o rings. To complicate matters the cases are not original to the bike. They are alpina cases. I was told the originals were damaged.

The oil on the clutch side was being pushed out of the vent hole in the filler plug. This stopped after replacing the seals. I do have the spigot type intake. It has been resealed along with a new intake gasket. Carb cleaner has been sprayed around this area when running to no avail. I have also sprayed it behind the stator with the side cover off, base of head, and along the case seams.

I am leaning toward splitting the cases and starting from scratch.

Tripp

Only the later seal carriers had O rings, no gaskets, and they were machined to take them. Earlier models used gaskets only. Only the clutch side has an O ring on the crankshaft.

If the plug was the correct colour and dry it's unlikely it was burning gearbox or clutch oil. My Ossa has been burning gearbox oil and the piston crown, head and crank are coated in a thin grey sludge.

Not sure what you mean by 'wants to rev'. Normally a weak mixture caused by sucking air will cause the engine to run on when the throttle is closed. An engine burning gear oil won't do this, it will just run roughly.

Are you sure the carb isn't worn, have you swapped it with the carb from the other bike to eliminate a possible cause, if that one runs correctly.

Sorry. A poor description on my part. After a couple of blips of the throttle the engine runs at high rpm with the throttle closed. It seems to be getting air from somewhere.

I did swap carbs, but not the slides. I will give it a try with the complete carb tomorrow.

Thanks,

Tripp

hello saw miller the later crank seal holders look like these.

Just a guess ... as You have installed a Mikuni carb to the engine there might be an issue with the carb to intake manifold connection, ( had a fitting problem too while mounting a DellOrto instead of the Bing ). May be the connection might not be not enough thight... I would check the connection, not only when idling but too when rev. up, just to sure ...

i have a mikuni it has brass peice fitted to the Airbox intake side the seal on the rubber boot is alot better.

Installed a new set of stator side crank seals. Swapped carb from the other bike. Same scenario. When I get the air screw set where it pulls good off the bottom, 1/2 turn on 1 carb and 1.1 turns on the other carb, she wants to run away. Rode the bike for an hour or so and it seems to be getting hotter than it should. Running 110 octane race fuel. 52 to 1 golden spectro.

Sprayed carb cleaner around the intake and the base of the head again with the engine running an revving. No luck.

This should not be this difficult.

Attached is a picture of the stator side seal plate.

Tripp

just a thought have you checked the carb jets to see if there the correct size?

Confirmed jet sizes with Hugh's Bultaco in New York yesterday. Everything carb wise seems to be perfect. I played around with the float height and clip positions.

The engine just will not run correctly.

I went ahead and ordered a bottom end kit from Hugh's. Maybe something is going on along the case seams. At least I will be starting from scratch.

Tripp

Broke down the engine today. Wrist pin totally shot. Suprised it did not lock up. Think I am done with this one. Parts bike.

Tripp

Sorry about the bad wrist pin. But I think it's to nice a bike to brake for parts. Put a new rod and wrist pin and bearing in it. All the parts can be had. But just my 2 two cents worth

Sorry about the bad wrist pin. But I think it's to nice a bike to brake for parts. Put a new rod and wrist pin and bearing in it. All the parts can be had. But just my 2 two cents worth