Need to pick yall brains...linhai bighorn 300cc 4x4 side by side utv little over 500 miles. Neve a problem just went dead and won't start back. 145psi compression,fire on plug that will knock yor elbow off,getting plenty of gas,adj valves, just turns over and will spit back thru carb if you hold gas down while cranking but will NOT even act like it's trying to start ?????

 

Have you confirmed the timing?

 

Yes cam gear and flywheel line as they should

 

Usually see backfire through carb when timing is way off or 180 out. Did the timing get changed when adjusting valves?

 

Checked it twice just to be sure, have shot it with starting fluid and still won't even act like its trying to start , has every thing to run but dead in the water

 

Have you tried changing the timing again by 180? The crank would need to make one full rotation and the cam stay at TDC.
Can you get a picture of where the cams are lined up when at TDC?

 

While i agree it sounds like a timing issue, their should be signs that it jumped timing especially if it jumped 180 degrees. Im assuming this machine is carbed? Check the carb floats and adjust if needed and clean the jets in the carb. Just had a similar issue on a atv i was given to get up and running. The float was miss adjusted causing the machine to flood every time i tried to start and would not even start on starting fluid. Also check for vacuum leaks i also found a gasket in backwards causing a huge vacuum leak.

 

I doubt that the timing jumped 180, I was thinking that OP may have changed it and put it back together on the wrong stroke. Needs to be be TDC on the compression stroke, not TDC on exhaust. Or there could be an electrical issue causing spark at the wrong time, but still have spark.

 

It's never been tore down , timming chain tight no way it jumped 180, it's dead on TDC checked it twice to be sure , could it have sheered the fly wheel key ? any one had voltage regulator do this on one of these I know the suzuki quadrunners will but they will crank just not run good , I ordered a cdi just to rule it still dead in the water had carb off twice to to satisfy me

 

Yeah the key could have been sheared off, I've seen it in an old Suzuki quad. I have also had an arctic cat with a flywheel that fell apart. Still had spark, but wouldn't run because it was happening at the wrong time.