My '01 sportsman just one day became very hard to start, SOMETIMES. Some times it will spin over ok but most times it acts like way too much compression. If i hold the start button for 2-3 seconds or cycle it a few times it will finally roll it over just enough to start, then runs perfect. (not in super cold winter days tho.) I used to be able to pull start it but now there is now way, just too hard! Also if i use my lithium boost pack it will turn over and start. So here is what i have done to it so far but no luck on fixing it.

1. new starter
2. new battery
3. new cam
4. new exhaust rocker
5. adjust valve clearance

I'm at a loss, its still a great running wheeler so I hate to get rid of it. Any Ideas what to do next?

 

Did you ever figure it out? Mine is the same way and I replaced everything you did.

 

No I have not. I had a suggestion that maybe the flywheel key has partially sheared and threw off the timing. When I get the time and ambition I’ll take a look at that.

 

Interesting, please update if you find anything. I will do the same

 

I’ll try to get to it sometime this summer, not sure when

 

I replaced the same parts you did and still dealing with this same issue.
Did you ever get it figured out?

 

I have not worked on it yet. Too busy

 

Have you removed the spark plugs to see if it cranks faster without load?
I got the same issue as you, but when I remove the spark plug the quad turns over like normal.

 

Update: I finally got around to working on it. I adjusted the valves; they were out a few thousandths. I also messed with the decompression mechanism; there didn't seem to be anything wrong with it. It's starting fine now, so I guess it was the valves. I wouldn't think that a tiny amount would make that much of a difference, but I guess it did.

 

Update 2: I let it sit for a couple weeks and now it's back to how it was.