Bought a 90 two stroke atv project a few days ago and have run into a snag.
The spark is excellent, compression good, plug new, and the carb is brand new also- fuel flows freely to the bowl.

Tried kicking her on today and got nothing. Did a few plug chops and it's bone dry. When I put my hand on the carb mouth it is sucking hard, good vacuum. Also, the inside of the carb is wet, which makes me think fuel is flowing.
I even tried shooting gas directly into the carb boot (through the carb)... still dry plug.

I have plenty of experience working on 2 stroke outboards and 4 stroke bikes, but little experience with 2 stroke atvs. There must be a reed valve system in place, maybe that's the issue?

Ideas? Thank you

 

If you have good compression and spark,but fuel/air mixture doesn't reach the plug,one of the most common things in two strokes causing this is lack of lower end compression caused by leaking crank seals. If they're leaking bad enough the fuel/oil/air mixture can just blow out the seal areas and won't have enough pressure to push any remaining mixture up the transfer port for ignition. Here's one animated video on how a 2 stroke engine works.Several more on you tube.

 

That makes sense. I'll check the lower case to see if there's leaking. It would be evident yes? Signs at the flange of leakage/blow-by? I would love to not have to pull the motor, but o well.

Thanks

 

Yes if it's leaking bad enough you'd see an oily mess around the crank seals. Only other way to test for leaks is through a leak down test to see if the head gasket,base gasket,crank case itself or seals are leaking.