My '86 Moto 4, 225 cc set up all winter. I have drained the tank and put in fresh gas. Replaced the fuel petcock, taken the carb apart and cleanded. After it sits overnight, it will start right up and run for about 10 seconds and die. It will not start again. I have disconnected the fuel line at the carb and it has a nice fuel flow out of the tank. I took the plug out and it's bone dry and has a good spark. I think I have a fuel flow problem. The carb floats don't seem to be "water logged" which would keep the fuel flow shut off. Anyone have any suggestions?

 

does it seem like its flooding at all? can you smell gas pretty good? it might be that the carb was thoroughly cleaned enough and still has tarnish or dirt inside the carb cutting off air or fuel flow, i guess low compression could be something that would make it do that also

 

Try spraying some starting fluid/carb cleaner into the carb. or put around a teaspoon full of gas into the cylinder then try to start. If it tries to start then there's a fuel problem. Check to make sure there is good fuel flow through the fuel line going to the carb..

 

There is no gas smell after trying to start for 10-15 seconds and the plug is dry. Is there any carb adjustment other than idle speed? There is a needle valve screw on the bottom of the carb outside the bowl in a vertical position. The screw is run down all the way and the tip of the needle is visible in the throat of the carb. There is no spring or O-ring on the screw. Can this be an air/fuel adjustment of some kind that is not adjusted properly? The motor will start nicely after it sets over night. I suspect this is due to a small amount of gas getting where is is supposed to be over time. Once this gas is used , the motor dies and won't restart.

 

It sounds like the fuel bowl isn't filling up properly. When it acts up again turn out the drain screw and see if there is fuel going out the hose. If very little fuel is coming out of the hose, I would check the fuel flow on the fuel line. If fuel flow is good then there is a problem with the carb. check the float , float valve assembly and the passageway that leads from the fuel inlet to the float valve.

 

Thanks. I will check out needle valve and float level.