Motorcycle Repair: carburetor vacuums, rich mixture, cold engine

Question
i own a 1972 yamaha dt110cc , i know that u work on hondas but am hopping u can tell me that all vacuums needs to be free of dirt cause i take the spark plug out and its always wett off gaz it starts right away when i crank it but does not want to run long and will not start back again after untill i remove the plug again so what can u sugest that i do with this should i change my spark plug cause it as a week spark also ???? thnkx ...

Answer
The problem is not with the plug. The engine is getting too much fuel.  It starts easy the first time because a cold engine likes a rich mixture but as soon sit starts to warm up, the mixture is too rich and and it won't burn.  Most engines require between 13 to 1 and 17 to 1 air to fuel ratios.  If you get too far outside of that ratio, the engine won't run.

You'll need to check the carb and see if the float levels are right and make sure the jets haven't been oversized by someone thinking they could make the bike have more power by giving it more fuel.

Regards
Rich