Originally Posted by fishheadstew
I have a TY250 (Yamaha Trials) -1974 that is in great shape. It starts up fine, revs, as well as idles just fine. When I place in gear and accelerate it bogs down. It's like it's choking for fuel. I can hold the choke down and this helps a bit, but eventually dies. Does anyone have any idea what might be causing this. I've been through the fuel system about three times already. Taking all advice as would like to get this thing up into the hills and start riding the ridges... thanks for any help you can provide..
I had about the same symptoms with my Ty250a a couple of years back. It was a barn find that had not been run for a long time. I had put a new mikuni vm26 carb on it and it started dying on heavy accelleration only to start right back up again. It would run fine in neutral but in gear under a load it would start sputtering and die. I posted the trouble on TC and someone said to change the points and condensor as it was probably the condensor. I had thought it was fuel related all along also but thought it was worth a try as I had no idea what shape the points were in. Thats what it was! Ran perfect ever since. If you do, put a new crank seal in it while you have it open.