2001 yamaha warrior YFM350x Popping Noise

[Chase Cook]

 I have a 2001 yamaha yfm350x and it has a brand new top end, new carburetor (stopped the leaking problem and is now getting gas to it), new CDI box, new stator, handlebar switches work, off-and-on switch works, new starter solenoid (works), new neutral relay (works), ordered a new Rectifier on its way, good strong blue spark. Has compression, valves are right. Timings is right and is TDC. When I try to start it it just makes a loud popping noise like its backfiring but it's not because its not running when I push the throttle all the way and when i barly push the throttle it try to start but won't, so I'm trying to figure out what could be the problem not starting now, Getting very fustrated with this thing and put some work and money into it and it's not still not working. This is the only atv I ever had that I can not figure out the problem to get running. Need help please..

Edited September 18, 2019 by Admin
Added issue to title and moved to Yamaha ATV Forum

[Frank Angerano]

Just because the piston or like you said timing is at TDC does not mean it’s not 180 degrees out. That’s exactly what it sounds like to me.  I’ve been there and done that.   

Take a step back and a breather and check it again.  Don’t let the frustration get to you.   It’s most likely something silly that was over looked.  First check that it’s not 180 out and go over the timing one more time.  Pull the plug also and check the color to see if it’s black.   If it were a fuel thing you could spray a drop of starting fluid into the air filter and it would start. You can try that first if you want.   My guess is on the timing.   

[Chase Cook]

Ok thanks frank. I'll check the timing. I'll also advance it one tooth and reverse it one tooth to see if that will fix the problem.. thanks for your help..

[Frank Angerano]

Your welcome. I wouldn’t advance the timing though.    I would study the timing sequence and verify that’s its spot on. 

[Chase Cook]

Ok thanks.