I just got the motor back from my local atv repair shop. When i put the engine in it took a long time to start and now it's not hitting on both cylinders, sometimes it does and sometimes it doesn't,, one minute it will hit on both and sometimes just one of the will hit, like it takes turns on which cylinder is gonna run, here's what i had done to it, i had a new crank and rods installed new pro-lite wiseco pistons, cylinders are bored to 60 over, boyesen pro-series reeds,,, boost bottle, the carbs are jetted with 240 main and 27.5 pilot, the needle is in the third setting, and the TOR'S is eliminated, it has a DG full exhaust (on it when i bought it) i was breaking in the engine with 93 octane gas, yamalube 2-stroke oil(20.1) the key switch was removed when i got it, and the on-off switch doesn't work, any info would be great, um running out of patience here,,

 

So one cylinder isn't always getting spark? Since the complete motor was out, and as dumb as this may sound I have done it a few times before, make sure all your ground wires are clean and connected well. Any shortage of ground can cause that.

 

one time the left side isn't then the next time the right isn't,, one pipe will be hot and the other might be cold, or warm,, sorta sounds like it's under water, i do see on alot of these things that they run alot higher jetting?, but i will have to check my grounds and make sure they are ok, thanks for the tip!

 

check the stator. i think a freind of mine had that problem and it was a peice of his stator was broken