Recently bought a sportsman 500 ho efi. has 145 hours,and there is some sort of rattling noise comining from the engine,seems to be on the right hand side,i can here it from cold start at idle and seems to get louder at higher revs espeacially riding if I hammer on it and a lot of people say that these bikes all have that noise and its normal howerever I really just want to know what it is! I changed all the fluids and spark plug. checked valve clearance and even took the bindex off and cranked with the pull rope to make sure it wasn't from the bindex.There is nothing that I can find that is loose. Any ideas?

 

Since you removed the bendix this would have eliminated most of noise from the recoil side,the only other thing I can think of is the slotted nut holding the crank sprocket in place. Reverse threads but this nut can still back off and hit the stator plate and make noise. If you want to check this nut out,the flywheel has to be removed,mark the stator plate and the engine case for reassembly and then remove the stator plate assembly. You don't have to have the slotted nut socket as a punch can break it loose and also to retighten if you wanted to locktite the crank shaft threads anyway, whether the nut backed off or not.Blue locktite is fine to use.

 

So the nut is between the flywheel and stator? wouldn't this cause the flywheel to be loose?Thanks for the help btw.

 

The slotted nut hold the lower crank sprocket(that has the cam chain) in place. It's behind the stator plate.I've had them back off and the nut would rub against the back of the stator plate and make noise. May or may not be the problem you're having,but first thing that came to mind.

 

Worth a sho . I'll post what I find out. Thanks.