Recently I bought a chinese go kart with a 110cc chinese engine on it> Im not sure of the brand and I cant find any marking on it. I had to replace the piston and head and valves bc he replaced the head after breaking off the exhaust in the old one. Long story short when he put the timing chain back on the new head he didnt have it on the tension gear but behind it. So starting it bent the exhaust valve and put some nice marks on the piston from the valve hitting it. Well after rebuilding the engine and timing it properly its back together but It wont start. It has spark, and it sounds like its trying to hit but it never will> if I use starting fluid it sometimes will start but sometimes when starting and then hitting it with some starter fluid the starter sounds like its laboring really bad. Its done this with the carb on to, especially in choke. Ive checked the timing twice and its all on. So I grabbed my timing light and checked it. The timing light has it sparking at the two lines before the F line. So Im thinking that its firing well before TDC and the starter is actually fighting a slow burn in the chamber. Question is, is this a CDI problem? I can't manuyally retard the ignition timing. The CDI that is on it is a 5 pin but I think its only a 4 pin system bc there are only 4 wires running to it. The guy I bought it from gave me 2 other CDI's with it all 5 pin. One of them also produces a spark while the other does not.

 

Well I have some more info. This is a 5 pin system bc the power wire is AC. So the dilemma continues. Using the timing light its sparking on the first line on the flyweel, not the fire line.