I have a new 2004.5 Sportsman 500 HO with about 170 miles on it. Just recently I noticed that after it warms up I can hear a knocking sound. Seems to be coming from the engine. I checked valve clearances and they are fine. Anyone have an ideas or suggestions as to what this might be ???? Knocking seems to go away at higher rpms or aleast I can't hear it then.

 

My 04.5 SP400 does the same. I am concerned about it, but it hasn't caused any problems so far. I am at 450 miles currently.

 

Try driving it on pavement and down hills and let off the throttle. You will be surprised at the noises it makes. Dobie

 

Yep, they sure do make a lot of funny noises. Wonder if maybe the knock at idle is the oil pump. Some pumps make noise at low speed ...........

 

its normal.....as tough as it is to say its normal.....i think gm motors and polaris motors are made the same....cuz they all seem to knock.....ahahah

 

This is my 3rd SP 500 HO and the other two did not have an engine knock. I've been around a lot of Polaris's and have not heard this knocking noise before so that's why I'm concerned. Lo

 

hmm thats odd...because ive had 2 sp 500's they knocked.......my one buddy has an H.O it knocks.....and my other buddies dad just bought a new H.0. and it has like 200 miles on it or so...and it knocks.......i to was worried but after the dealer looked at it and said its normal....it took a while for me to stomache it....but the first sp had around 2800 miles on it...hard miles........when i got rid of her and she still is goin strong.....

but i do know where ur coming from any kind of knockin isnt good...and i do know its hard to believe its "normal"

 

I think it's oil related. When my motor is cold it sounds great. Only when it's up to operating temperature does it start knocking, and then only at idle. If it were an internal engine componet it would get worse with increased RPM, but it doesn't. My theory is that when the oil gets hot and thins out, it doesn't cushion the oil pump as it does when cold, hence the knock. This is assuming that it's a gear type pump, which I don't know for sure. The Clymer manual doesn't show a schematic of it.

 

o yeah its normal it knocks loud even with your helmet on you can hear it somewhat. i was worried about it but my dealer told me it was normal and i still wasnt sure about it but when u floor the atv it makes some good knockin too so i donno what to say

 

I was wrong, the Clymer manual does have the pump info.

Seems that they all do it, so, if it aint broke it don't need fixin' ...