91 yz-125 compression test, no start.

[gregor01]

Hello all

 I'm new to this forum and to 2 strokes.  I bought a basket case 1991 yz-125. Looks like lots of aftermarket parts and mucking about. I replaced the stator and rewired the bike, I have a strong spark and the carb is clean, reeds are boyseen with no outter plates. The bike just will not start, kick or roll. I did a compression test and got 120 psi after 5 kicks. Do I need to do the piston and ring? I have lots of mechanic experience with 4x4s and cars. Help me defeat my gremlin.

Thnaks

[Tristianmoss13]

Remove the spark plug add a few drops of gas in the cylinder put spark plug back and then kick,,,

try some carb cleaner directly inside carb, remove the filter even though you say the carb is clean and try kick starting again,,,

If no response still next remove top end and make sure piston ring is lined up and the arrow pointing forward, then align the piston at top center, tighten everything back up and try kick starting again

[gregor01]

Ok. Christmas has come and gone and this dang bike still won't run. I have good spark,the stator is new and wiring checks out, plus I can see the spark when testing. I rebuilt the top end with a new piston and gaskets, compression is now 155b/ft. Could the whole problem be the carb? Timing? 

[whyzed2T]

Timing could be out. Or a faulty coil maybe? I had a similar experience with an '02 yz125. Ended up swapping the coil from a friends '03 and it fired up on first kick.

[gregor01]

I'll double check the timing nd can run a test on the coil but considering I have spark it shouldn't be the coil. Gonna pull the carb apart, maybe it's something simple like a bad float.