Help me please, I'm lost. No Spark
 

Alright guys, new member here. I've got a GY6 150cc Go Kart that I pulled the motor off of and rebuilt the top end about a month and a half ago. After putting it back in, it started right up and ran for about 15 seconds, then lost spark. And ever since then, I've had to luck getting it back.

I later found a small nut behind the flywheel that tore up one of the coils on the stator (oops :shrug:). Removed it and grabbed the multimeter and started testing and replacing parts.

I've tried multiple spark plugs. I've replaced the ignition coil, pickup coil, 6 pole stator, CDI, disconnected the kill switch (if the wiring diagram was right at least), and of course fully charged the battery and also checked while being jumped from my car. Nothing seems to work. Does ANYBODY have any ideas at what the problem could be? I would be EXTREMELY grateful to anybody that helps.

Edit: I have not replaced the fuse but the fuse looks good. Turning over well, has fuel, has compression. I removed pin number 5 from the CDI plug, which from what I understand would be the killswitch. It also has a new solenoid.

Diagnose, diagnose, diagnose. You need voltage from the stater to the CDI, this charges a capacitor in the CDI ... then you need a voltage signal from trigger coil which allows the charge in the capacitor to cause current in the primary of the coil which causes a spark at the spark plug. There are gobs of youtube videos that explain this better than I can. Watch a few and learn the theory of how the ignition system works then use a multi meter to determine if the proper voltages are what they need to be to produce a spark. Firing the parts cannon at a problem works but diagnosing and replacing what is needed is how you know you've fixed it properly.

That's the thing. I've done all those tests and all the parts seem good.

I ended up taking out all of the wiring and combing through every inch of it. Fixed a few issues, there were exposed positives and grounds in multiple places.

No shorts now, I've got around 170psi compression, getting good fuel, carb is clean, have good spark, valves are good, timing is good, starter motor is good. But it still. Won't. Start.

I've been out there all day and can't get it going. Does anybody have any ideas on what the issue could be?

This is going to sound crazy, but this is what happened to me before. I had a beloved moped with a V1 motor. Built it way back before the internet existed so help was not close by. Anyways, was riding it to work one morning and it just shut off. No warning of any type. Just stalled. Was getting fuel. Getting strong blue spark. Just would not start. Got it home and keep messing with it. No luck. So, I pulled the stator off just to check. Turns out the 2 screws that held it in place broke and the stator flipped a perfect 180 degrees upside down! If I never removed it I never would have figured it out. One of the screws took a chunk of the case with it and I ended up selling it for parts. We bought a Carter Brothers go cart for my wifes nephew one Xmass. The adults rode it and burned the clutch up and expected ME to come and fix it!? Needless to say its been sitting so long now its only good for scrap metal. My guess is timing related.

Here is a link on how to diagnose your ignition. You must promise to come back and tell us what you found wrong and how you fixed it....
https://www.buggydepot.com/tech-cent...uide-no-spark/

Hey Roscoe, thanks for the guide but I had already been through it multiple times and was still left scratching my head :hmm:

But the issue is fixed now. I have no idea what the problem was, honestly. Redid every bit of wiring on the damn thing and that didn't bring the spark back, let it sit overnight and the next day it started up with great spark! I don't know what was wrong with it.

Red Faced Rosco.... gulp..... I was having the same problem and finally ended up swapping parts. I think it turned out to be an interment CDI box in may case. Everything tested good but it wouldn't start and weak spark, sometimes start, sometimes almost start. I hate firing the parts cannon at things but when all else fails start changing parts till it goes. Watching a really good guy diagnose and fix things on the cars South Main Auto on Youtube. He knows his stuff and is entertaining as he goes along.

It was running again until it wasn't. After getting it running, it got an oil leak from the crank case cover behind the flywheel. Guessing the old gasket couldn't handle the new compression. Then, the CVT wouldn't disengage so trying to start would just lunge the kart forward and we actually had to lift the rear tires off the ground to start it, then floor it and lower the jack to get it back to the house. Stopping the kart meant killing the engine. I pulled it out to fix these two issues, got it all back in and surprise! Starter won't turn. Pulled off the starter and it is working great when not on the engine. But when it's back on the engine, it seems like everything is shorting out.

I can turn the engine over by hand easily, it's not seized up or anything. But even ignoring the ignition system, if I put power directly to the starter all I get are sparks on the ground and heat. This thing is frustrating.