Carbide 150 wont start

[binkerton]

Hello, I am stumped. My kids' buggy up and died the other day after about 10 min of driving and I cannot get it to start again. It spins just fine but will not fire. First thing I checked for was spark. It definitely has that, my kid decided to go ahead and crank it before I could ground the plug to the engine so it sent voltage all the way up my arm. So I tried spraying a little starting fluid in to get it to fire, nothing. I pulled off the filter to double check it wasn't getting choked, nothing. Checked valve clearance and it was perfect @ .004/in .005 exh. Checked to make sure the vacuum operated check valve off the fuel tank was operating, it seems to be fine. Took the carb completely apart and cleaned/checked passages. Oil level and color appear fine. Spark plug tip looks good. Battery has good voltage.

I'm looking for any help on what to check for next. It just doesn't make sense. The thing was running great, then when they brought it in to park it just died as they came to a stop and never started again.

[binkerton]

New development. Went out and played around with it a little more. Actually got it to start and run with my foot in the throttle but as soon as I tried to bring it down to idle it died again and I'm back to not starting. But I can narrow it down to carb issues I believe. Would this be an idle jet? I don't have a lot of knowledge on the different parts of the carb or how it works. The thing had sat since last summer so I imagine some deposits could have formed and got stuck somewhere. When I bought the thing back in '15 one of the first things I bought was the UNI filter kit and a #125 main jet to go with it.

[metalstudman1]

Is this the same buggy as your other post- about low compression?

[binkerton]

Yes it is. I've tried everything I can think of. It's getting fuel, spark is good. Just doesn't make any sense. It acts like it wants to start but just won't go. I have gotten it to run twice now after lots of cranking and holding the throttle at different positions but only those two times and both those times it would not stay running on its own. As soon as I let go of the throttle it would die and would not restart. I've had the carb apart 3 different times now. Nothing internal is messed up, it appears to be working as it should, no blocked passages either.

[binkerton]

Took the top end apart tonight. Found 2 cracks in the ring lands on the piston. Cylinder looked ok and rings seemed ok. Gonna mic the jug at work tomorrow and see what it comes out to. Wonder if I should just do the whole jug and piston kit or get a new piston and rings.

[metalstudman1]

I always try to replace both-jug & piston since it's already apart and to confirm the head gasket it good, but do what you can afford! The cracks really don't explain it not running though unless the rings were rolling up & down putting the piston in a bind in the jug.

[binkerton]

It was the top end. We bought a rebuild kit and replaced the jug, piston and rings and it runs like a champ again. Fired up on the first try.
Smoked like a chimney for the first 5 min or so until the rings got worked in!