Motor stopping

[Lousailor]

I've just finished an Ebay special minibike project with my son. He's very excited and it works well, but he's frustrated because after a while the engine stops and won't start. There seems to be quite a bit of carbon build-up on the plug, but could it be due to overheating? It's a Tecumseh powersport 4.0 HP model with the fuel tank in front and the fuel line under the cover going back to the carb, which is right under the exhaust. Also because of the frame we used, the engine is tilted forward, so the fuel has to run uphill a little to get there. Any help would be greatly appreciated. Thanks

[robertdjung]

carbon build up is probably running too rich, or not a hot enough plug. First, make sure it's the right plug. (get the numbers off the engine and call a lawnmower shop)

then, replace the plug with a new one.

then make sure you've tuned the engine right and it's not too rich or lean. Find that adjustment and lean it out if you can.

then see what happens! :)

[ryf]

and don't forget to see if the new plug or old plug needs to be gapped, sometimes plugs get dropped, etc. a gapping tool at autozone is like 99 cents..