I have purchased a non-running quad for my kids and seem to be stumped. I have replaced ign. switch, lighting coil, and source coil, used rectifier, gone thru entire harness. She has spark, gas, compression about 125lbs. will not fire? I am trying to figure if CDI, or what? The lights do not come as they are supposed to when switch is turned on. Elec. start works fine, lights work if I power direct to battery. Please any advice would be appreciated. Thanks in Advance.

 

Has the engine been apart? Is the timing set right? What does it do when you turn the engine over? If you have gas, compression, and GOOD spark at the right time, it oughtta fire.

 

Hey thanks alot for responding- you all have been wonderful- I am learning alot..
I have taken the head, jug off to inspect rinigs after I thought compression was low, ring gap was ok and honed cyl. actually it was very clean, not much carbon, it has a 50 piston in it (maybe means 50 over?). Put back and compression is not consistant but have cheap tester - hard to find one for small plug threads so using the rubber tip one, reading 100-130. I figured even with lower comp. it should run like crap, but just cant get that far. The engine cranks had it almost want to fire 4 times, getting vacuum when I put my palm over carb intake. I have gone thru timing many,many times all things line up and the valves tight at TDC. Thanks again.. Chris

 

Are you sure you have a good spark? And are you sure youre getting gas? I used to put a few drops of gas down in the sparkplug hole, then put the sparkplug back in and try to crank it. That way you know you have gas.

 

Finally got her to fire.. After many, manyhours testing electrical, pulling carb at least 8 times to try to adjust floats, it was a fuel problem. The choke was not correct and needed to be on half way, throttle needed to be held wide open, and air tube needed to be on. Runs like crap and floats are still wrong, but at least it runs. Now I need to try to tune carb in and still adjust floats from overflowing gas from the bottom tube. Thanks for everyone input.

 

I got a yfm200 from a relative and he said it had not ran for 12+ years. I've purchased a new battery and put it in, only to figure out the lights on the panel wouldn't turn on. The electric start won't work, and I've tried the pull start and that won't work. The engine will turn over, in case you're wondering. Any ideas?

 

ok so i replaced the fuse and the lights will turn on but it will only turn on every 10-15 tries. When i press the electric start button, it will make a weird sound and turn off.