sp 500 won't rev.
 

I got a '99 sportsman 500 that idles ok but when reved up sputters and acts like it's pulling air(leaning out). It stays running and will drive ok. Also it doesn't seem like ignition. It sound like a hole in the exaust but is not the case. the carb boots are good. jets clean, diapharm fine and all stock. I am now down to valve and know they need adjustment. i am not sure what the spec it the clearance (~.006"?) but was wondering if any one had any suggesion as what it could be.

sp 500 won't rev.
 

Give the valve adjustment a shot. The specs are .006" on the intake and exhaust at TDC compression stroke. Thats for the 500 H.O. Though. I would assume that it is the same for the non H.O., but hopefully someone can confirm that. The exhaust valves share a rocker arm and both have to be adjusted at the same time.

sp 500 won't rev.
 

Have you changed or cleaned your air filter?And when you check your valves inspect the cam lobes real good for wear. .006 is the setting.

sp 500 won't rev.
 

Thanks, still have the problem after the valve adjustment. did see some exaust blow out at the muffler joint so i going to try and seal that up better. is there any chance the clutch is shifting up to fast and dogging the motor?

sp 500 won't rev.
 

Bypass your reverse limiter switch.

sp 500 won't rev.
 

Pop the valve cover off again and watch the stroke of the intake valves as you rotate the engine - then compare the stroke of the exhaust valves to what you just saw on the intake - My guess from what you are seeing is the exhaust lobe on the cam is going/gone and the exhaust valves are not physically opening fully to expell all the exhaust gas (ie - short stroke on the exhaust valves).

A really badly worn exhaust lobe on the cam will cause kick back (or starter drag) when using the electric starter, and the quad will be extremely hard to start by pulling the rope (feels like way too much compression)

sp 500 won't rev.
 

i can understand what you (quadwrench) are say it does seem to pull over hard if i use the pull rope. I can pull the valve cover again and see what happens. The plug looks really lean on the electrode and like a lot of carbon on the bottom of the threads. I am assuming the bypass switch needs to be shorted.