January 27, 200818 yr Author I just rebuilt my mates 125cc carb and replaced all jets and the needle and the sod wont run right, it ticks over great but when you accelerate hard it die's I've put the needle in ALL poistions and adjusted the fuel air mix and no change. Is there anything I'm missing, or could I have the wrong main jet? it's a 120. This is the carb that was running real rough last week and had no main jet in it! Regards Nick.
January 27, 200818 yr sounds more like an electrical problem?if its feeling like its running lean when its hot,might be a stator failure? ie when the stator coils get hot,the spark is getting poor no, that is a myth FYI: It's no myth, common problem with Beta stator coil, haven't heard of it on Shercos though.
January 30, 200818 yr I just rebuilt my mates 125cc carb and replaced all jets and the needle and the sod wont run right, it ticks over great but when you accelerate hard it die'sI've put the needle in ALL poistions and adjusted the fuel air mix and no change. Is there anything I'm missing, or could I have the wrong main jet? it's a 120. This is the carb that was running real rough last week and had no main jet in it! Regards Nick. I hate deals like this because if the bike did not even have a main jet in it, God only knows who has screwed up what! Go back oner the basics, be sure the fuel tank is venting properly, fuel is flowing through the petcock, vent hoses on carb are removed or clear, put needle back in 3rd groove from top. If you do not have a problem with fuel supply, yet it runs better with choke on, you may have a problem with crankshaft seals sucking in air, just a thought, any excessive slack in the flywheel if you try to move it up and down? Do you have a local dealer that can offer assistance?
January 30, 200818 yr From the initial symptoms, it sounds to me like the mag side crankshaft seal has failed, letting air into the crankcase and providing the lean mixture syndrome. Have a look under the flywheel and see if there is a little oil mist around the seal. Doesn't take long to replace. Other problem may be a split in the rubber inlet manifold. Bye, PeterB.
January 30, 200818 yr Author Just to cap, I've had the carb apart about 10 times now adjusted to various settings and all to no avail, what I have found was the main jet was missing and the idle jet was clogged, then to cap it all I've just found that the atomizer tube has been snapped in half!! the last owner must have had boxing gloves on. I've ordered the tube plus various jets and will start from there, the fuel is clean and free flowing, the airbox is clean and there are no crack's in the rubbers so no air getting in from the carb side. Once this lot is done and if it still doesn't run I'll pull the flywheel off and check the crankshaft seals, or wheel it down the local dealer, or even just burn the lot. Thanks for all the help. Nick
January 31, 200818 yr Even if you have a local with a 2.9 or 2.5 the carbs are virtually identicle if you can try one should run fine. Cannot imagine how you break the internals? I had a 125 of that vintage for a number of years, carby was never finiky, about 33 on the pilot jet should work fine.
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