I bought a BTM 50cc off e-bay this spring and 3 carbs later I still have problems with the quad. It runs fine once its warmed up but it takes a little either to get it going. Its a Zongshen 50cc 4stroke. I e-mailed the company and the outfit I bought it from and asked to buy a service manual for it. Got no answer.

Thanks...

 

I have a Kazuma 50 and had similar problems with my carb, or at least I thought it was a carb problem. Do a search for "carb woes" and you will see the post and responses. Turned out that the valves needed adjustment. From what I can tell, the Zongshen is the same engine that the Kazuma uses, which is a clone of the old honda engine. As far as a service manual, I found a guy on ebay that sells a cd of different manuals and diagrams that pertain to the engine. I don't know if there is a service manual specifically for these bikes, but this CD is pretty helpful with some good information. Do a search on ebay for Kazuma manual.....it's $9.99.

 

Thats why I wanted a service manual checking the valves was my next step. The honda 50 and trail 70 are really fussy about there valve settings. Thanks I'll check on the manual.

 

I have a question. My 50 came with 19mm carb. It had a horrible dead spot. If you throttled up hard it would die. You had to ease into the throttle. I put a 15mm carb on it and that cured the dead spot but now it won't start so I will try the valve adjustment. What size carb do you have?

Thanks

 

Valve adjustment is the problem. .004 if you can get a gauge in the tight area. if not make sure there is some play when valve is closed. If the valves are too tight you loose compression and it will be hard to start when cold. The engine is the same as an old honda Z50 http://www.hondaheaven.org/files/manuals/honda50.pdf to download shop manual