so for most quads theres an inspection port low on the left side of the engine that a flathead screwdriver will remove then you look down and spin the engin by hand until you can line up a T mark in the opening. then you take the cover off the timing chainand it should have a location for Top dead center marked on the sprocket and behind that on the case there should be another mark also denoting TDC. if you have the three marks lined up properly you are timed correctly.
If your having other timing related issues look at your cdi or check the specs on your valves and make sure theyre set properly and do an inspection on the cam to decide if its worn out.

 

Ok i have done all of this now and everything is in order. It almost feels as if something probably piston is hitting the spark plug preventing it to turn. Eventually gets past it but still wont let it spark. Have spark outside of engine but not inside..

 

honestly more likely a bent rod. if the plug was being hit it would have damage. when you had the top end off did you look at the cylinder walls?

 

Have it off again. Will upload some pics

 

Let me know if you want more pics. The whole thing is apart rn. Im gonna check out the valves n

 

check under the piston and see if it looks mangled see if the piston binds or sticks when adjusted back and forth check the base of the piston and see if theres any signs of contacting the sidewalls. since you have everything apart.

 

i did already move it back and forth nothing sticking or binding but will check for those other signs. Im lost nothing alarming or displaced. When i took it apart i was hoping to see damage. But nothing. Everything is good. I dont get it

 

Hey so I have an early 90’s Yamaha Timberwolf.
New battery (with jump to car battery too), new starter, oil good, can turn motor by hand.
still struggling to turn over with the plug in. Take the plug out and she’s turns over beautifully. Ran starter and put under load out of the motor too and it doesn’t fault at all. I’m a bit stumped. Any help would be appreciated

 

Most of the advice in this thread is rubbish. First you need a good, fully charged battery. All heavy cable terminals need to be clean and tight, including earths to frame and engine. Try spinning engine over with plug in, and plug lead off, if it turns over better, ignition timing is off. This may be because the flywheel key has sheared, however I have known ignition timing to be right but, if the engine slows just before TDC, it fires the engine backwards. Reasons the engine can slow down on the starter are, one way starter clutch slipping, or binding in gears between starter and one way clutch, both are most likely to happen just before TDC as compression is greatest then.

 

Thanks for your help mate. I got my **** in gear and fixed the pull start so I could isolate the issue. Got the old girl fired up and runs like a dream so my guess is the starter is toast. Until I can find a starter I’ll be using that. I learned a lot pulling it apart to check timing etc so it’s a win win