Need more low end on my 1980 Yamaha Tri Moto 125

[gabeshong]

I have a 1980 Yamaha Trio Moto 125. Stock are box was bad so I put on a aftermarket airfilter right on the carb. I was vary lean, I jumped from a stock 110 main jet to a 190 and its a lot better. But Im still lean on the low end. Ive searched for bigger pilot jet and cant find them and even had one guy tell me you cant get them. What other options do I have and what else could I do to help low end fuel? Thank you!

[Mr_RPM]

lower your needle clip, that will help.

[Yamaha_Rules69]

It kinda makes me wonder when you say you went from a 110 main to a 190!? That is a huge jump, and I would think it would be running really rich, to the point it dosnt run right. Most of the time for a air box mod, or a simple pipe change, a guy would go up two, maybe 3 sizes, in your case a 115 or 120. I wonder if you have an air leak somewhere? It could be the head gasket, or intake manifold, or left side crank seal - they could be sucking in air, making it that lean. An easy way to check the left side crank seal is to take the recoil off. Use a flashlight, and look inside, behind the flywheel if you can, or pull the flywheel off if you have the correct reverse thread puller. If it looks wet, and smells like gas, you know the crank seal is bad. Also grab the flywheel, and se if it has any up and down movement, indicating a bad main bearring. If this is the case, it is time for a complete motor rebuild. Its better to fix it now if it is bad, than to fry the motor, and have to buy all new parts, like piston, bore, rod kit, and main bearrings. Check for an air leak, and let us know what you find. Good luck!!

[gabeshong]

Thanks Yamaha_rules69, I started with a 170 main and still was lean, the 190 worked great. The air leak sounds like my next step. I dont have much time to work on it but Ill let you know what happens. I still need carb parts, Yamaha dealer is charging me $35 for a idle screw. I take a hole carb or parts if some one has anything.

[fabiodriven]

My guess is the crank seals. They are very commonly overlooked. People don't realize how important crank seals are to a proper running two stroke engine. They very well could be original in that bike and 25 years is a long time to expect crank seals to hold up.