I just picked up an old LT125 for my son that needs a little help. It was sitting in a guys garage for years and the story goes that he tried to rebuild the carb but it never ran right afterwards.
Anyway, I got it running but it starves for fuel. If I apply vacuum to the vacuum line the fuel pump works so I think I have the vacuum line connected to the wrong spot on the engine. When I got it, it was connected to the top of the carb but I think this should be just a carb vent. There is a nipple on the carb/ intake boot but there was a cap on it. Does anyone know where the fuel pump vacuum line connects to?
Thanks!

 

I have two 125's, and both of mine the fuel vent seem to be connected near the top of the carbs. I think you likely have an issue with either a bad diaphragm or a pinched/clogged fuel line. Another thing that is rather wierd, is whenever my 125's would act up, I would unscrew the top of the carb, crank it up and run it while running the slide up and down, careful not to pull it out too far. That seems to clear out the carb, lol.

I would bet your fuel issue is inside the carb. Also check for clogged jets if you take it apart. Use air to clean it.

LaterZ.

Also, it would be a good idea to find a diagram of how the carb goes together and the parts involved in case something is wrong or missing. Some ATV shops SHOULD be able to get you a microfiche of it.