Sherpa T 250 Erratic Carb

[swooshdave]

Hi Dave & all,

I will get new seals and give them a try. It has been suggested by someone near me who handles Ossa parts, that the seals MAY be common between Bultaco and Ossa. Does anyone know if this is the case?

Thanks,

--Kevin

I do not know about the Ossa seals. Regardless, get them all replaced. You should see a remarkable difference. Keep in mind that you also want to insure no air leaks around the carb area either.

[sherpat250]

Well, I pulled the flywheel and removed the crank seals behind it. (I was actually surprised to find two of them, installed back-to-back. Is it normal to have two seals here?)

The seals are 25x38x7 mm. One showed signs of leakage (oil/grease on the outside), and upon further check, I noticed that the fine circular spring inside the seal is broken. I think I may have just found the air leak problem! Anyone know where I can obtain new seals of this type?

I do not know about the Ossa seals. Regardless, get them all replaced. You should see a remarkable difference. Keep in mind that you also want to insure no air leaks around the carb area either.

[swooshdave]

You're in NY? How far are you from Hugh's?

[sherpat250]

Hugh's is on the other end of the state from where I am, but that's no issue with mail order. Unfortunately, he does not list crank seals on his website.

You're in NY? How far are you from Hugh's?

[swooshdave]

Oh, don't worry, they have them! Get calling.

[sherpat250]

Oh, don't worry, they have them! Get calling.

Hugh's had the crank seals, and I installed them (flywheel side only at this time) but they made no difference! The engine still stumbles off an idle condition and the carb mixture screw makes little or no difference. I'm told the other end of the crankshaft should have its seals replaced too, but that this would likely just cause a smoking condition, not an air leak. I'm convinced my problem is an air leak, but where else could it be coming from?

[totalshell]

bite the bullet, that Amal is made of soft alloys with easy wearing brass needle/jets etc. either change all jets , needle and slide or pump for a new carby either way your bike will run better and you 'll know for sure it aint the carb.

[sherpat250]

bite the bullet, that Amal is made of soft alloys with easy wearing brass needle/jets etc. either change all jets , needle and slide or pump for a new carby either way your bike will run better and you 'll know for sure it aint the carb.

Bike ran well when put away 28 years ago (I'm the original rider), so I don't think anything "wore out" in the carby. I have been through it and meticulously cleaned it out with air, cleaner solvent, and tag wire, so I don't think anything's plugged there. I did install a new air screw seal (O-ring), float valve, and carby gaskets, and still no change in operation at all. I've tried adjusting the needle height--no change. I'm convinced there is an air leak somewhere in the engine, and I just need to locate it. Thanks for the ideas though. I'll report back when I've corrected the problem. --Cheers.

[swooshdave]

Only one crank seal isn't going to do it. They can harden up with age just sitting there.

It might be a carb issue but you don't know until both seals are new.

[sherpat250]

Hello all,

I have an update on this problem that I wanted to share, in hopes of helping someone else. My carby definitely needed a good cleaning, and my crank seals were in poor shape too, but the major problem here was with the IGNITION. Yes, I found it hard to believe, too, but I discovered that the magneto wiring harness was incorrectly connected under the gas tank (where the barrier strip is). I found the green wire feeding the high tension spark coil, whereas it should have been the black wire, with the green earthed. I really don't know how I was getting any spark at all! It was a weak spark, but I thought it was OK as long as the engine was starting. I was wrong, as not enough spark was being generated at low speeds. Once I got the RPMs up it ran well (magneto turning faster=hotter spark), but it was an inadequate spark at slow speeds, and that was the cause of my problem.

So, now I have a new carby, new crankshaft seals, and a very hot spark. This bike is ready to run. VIVA Bultaco!