My new 03 500 is knocking. It is really bad at 20 mph in 4th under lite to moderate throttle openings. I called my dealer and they said that is the way all big bores sound that is a big piston. Gee, my 660 Raptor doesn't make any noise. So you other 03 500 owners, does your Cat knock. I called Artic Cat and they said that I must go through my dealer.....this is not looking pretty.

Chuck
03 Artic Cat 500 manual
02 Raptor

 

My 03' knocks a little bit at certain times. It's just valve noise most likely. Take it to the dealer and have them check your valves. They may be too loose.

 

Try some high test, if the knocking goes away you will know that it's a spark knock which can be fixed with timing or jetting.

 

My oldie does that a bit. If it sounds kinda like a diesel its normal.

 

I ran out my first tank and the second two tanks have been 100% 93 octane at 4000' elevation....didn't make a difference. I also don't think it is the valves because it depends on the load, not on rpm. I have came to the conclusion it is either piston slap or pre ignition due to running lean. I hate having to work on my brand new quad and having zero dealer and manufacturer support....makes me wish I would have gone with an inferior designed Honda, but at least it would have been screwed together right.

Chuck
03 Artic Cat 500 manual a knockin with 100 easy miles

 

I have an 02 500. It has the same noise I think. It's the compression release, nothing to worry about. 1500 miles and going strong. Try to ride an other Cat and see if it does the same.

 

Don't worry about it! Did you know Yamaha makes a diesel atv?? Well i got one!! (the kodiak is a knocker too.)