Aww, dear old Larry Ng, AKA Gone forever
goneforever. Oct 22, 2022
NO gap means missing spec in manual or eyes looked at valve gaps and see none?
?????????????
It has HLA (Hydraulic Lifters) or solid tappets.
Get the service manual and see?
And some information from me! Larry was always economical with words, failing eyesight.
Question moved from Cars and Trucks to model category.
I have two thoughts on this.
You either have water in the electrics from hosing the mud off, especially if you used a power washer.
Or
If mud and water got into the stator and coated the sensor for the CDI. It is magnetic, but in close proximity.
Basically strip and clean and spray WD40 in connectors.
Other ideas here. The ATV forums are a great resource.
https://www.google.com/search?q=2004+polaris+sportsman+600+backfiring
..
mine did the same thing & then it finaly quit running altogether...the gas gauge stoped showing in the display also. I pulled the old fuel pump out & replaced it with one out of a 97 ford areostar witch has an almost indentical pump & now the machine runs like new...and my gas gauge started showing again & I saved myself 500 bucks because the pump i used was gave to me...lol