I have a question and I'm wondering if any of you ahev experienced this. I have a 2000 Sportsman 500. I purchased it June 1st and it has approximately 150 miles and 22 hours on it. I noticed a knock. I took it to the dealer for its 20 hour service. I told them about the knock and let them listen to it. I was advised by the service manager that it sounded like a clutch noise. He further advised he would have it looked at. When I got the bike back approximately 3 weeks later I heard the knock again. I have a buddy that owns a Yamaha dealership and was talking to him about a guy that has a grizzly with what he thought was spark knock. He told me to advise him to put heavier oil in it and if it goes away it could be a rod knocking. He also advised me, that he believed the 0W 40 oil Polaris uses is too light and to use 20W 50. I just changed the oil in my quad to Castrol syntec 20W 50 and low and behold no knock. Now here's the question. Do you guys think this noise is due to the lighter Polaris oil or a rod knocking? I'm going to the Bad Lands in Attica Indiana this weekend for some serious riding. So if the engine goes, so be it. It's still under Warranty. I don't have time this week to get it into the dealership to be checked out. It took them 3 weeks last time to get it done.

 

I wouldnt advise puting oil that thick in it. I would olny go with 5w maybe 10w but only in the summer. In the winter only run 0w-40. Because the oil gets to thick and it wont run down to the oil pump. Ive heard from Polaris several times in their news leter about this. Also try running high octane gas too. Ive found with the high compression that the 500 has, it likes the higher octane for less spark knock. Hope this helps

 

My dad recently bought a 2000 sp500. When he got it home he noticed a knock also. Took it back for its first service and mentioned it. The mechanic said it was caused by wrong clutch spring I believe? He said he could put in a different color clutch spring and it would solve problem if Dad wanted. He opted not to since the mechanic said it wasnt doing any damage.

 

It's funny that this should have come up. I've noticed the exact same problem, when I only detect this "knock" at takeoff from a dead stop. It sounds like a single detonation, then everything sounds normal. I'm running mid-grade at the moment, and might switch to super. The clutch spring replacement does make sense considering when it is occuring, I will have to ride it a little more, and explore taking into the dealer.

 

Rod Knocks are rare occourances in Quad engines due to the fact that they have roller bearings on the crank shaft. knocks in the engine are ussually the result of to much piston to cylinder clearance and can be defined as more of a slap sound than a knock. I would guess this knock is as has been said in the driveline ,most likely the clutch.

 

I thank you guys for your input. I still have the knock, especially when it warms up. It sounds like its coming from the pull start side, I can hear it better on that side. Also I'm running 93 octane in it now. The gas we have here in NW Indiana is specially formulated during the summer months for pollution control. So the lower grades suck and cause alot of spark knock. I sometimes use an octane booster to help prevent this.

Well I hope the knock is in the clutch, I'll find out this weekend when I venture down to Attica for two days of intense riding and mudding in the Bad Lands. If it is a rod knocking and it blows up I'll let you guys know. If any of you are going to The Bad Lands in Attica this weekend, maybe I'll see you. I'll be riding the yellow 2000 Sportsman with the knock. Take Care and Ride Safe.

 

I have noticed the same problem is my 2000 SP 500. It really has me concerned as to what it could be. I don't want the dealership to hold my quad for 3 weeks to find out though. I'll have to give them a call to find out if this has been brought up before.

00 Sportsman 500 yeller
99 Honda 300EX

 

My '99 SP500 has a lightly noticeable knock in it also. I've tried to isolate where it is coming from, and I think it has something to do with the starter. It doesn't sound like an engine noise, but rather something just inside the recoil starter. I'm thinking that it's either the recoil or electric starter. Maybe something is vibrating in one or the other and sounding like a knock. I'm not worried about mine.

 

Some have the knock and some don't. Mine does my wifes dosen't. Only hear it at an idle, goes away when I give it a little gas. Sometimes goes away when it really warms up. I always suspected the decompression mechanism was ratteling around, but dosen't seem to hurt anything.

 

ive never noticed a knock on my 99,but since day one i have always ran 93octane gas.i hope those new HO motors doesnt have that.i might get the extended warranty.