Motorcycle Repair: ring replacement, polaris scrambler 90, polaris owners

Question
I am working on a 2002 Polaris Scrambler 90. The problem is with trouble starting or staying running at idle. It will start when warm and may hold an idle. The main problem is when throttle is applied. It will bog down and then the rpms may come up and accelerate as mormal. When this problenm occured before, ring replacemnt seamed to do the trick. Now I figure I can do this myself. I need some direction. How to, what to watch out for to avoid screwing up, special tools, etc. Thanks in advance.
Randy

Answer
Hi Randy,

I don't think replacing the rings is the fix for this problem.

I suspect a carburetor tuning problem.

Replacing worn rings without repairing a worn cylinder is kind of fruitless.

Perform cylinder compression and leak-down tests to verify the sealing properties of the combustion chamber. If readings are out of service limits, consider a top-end tear down.

With top-end disassembled, measure the cylinder, piston, rings, head surfaces, etc... Replace worn parts accordingly.

Learn to read the appearance of the spark plug to know what is happening within the combustion burning process. Make carb changes accordingly to correct the air-fuel mixtures.

I do not recommend a top-end repair from anyone not experienced. Fixing mistakes is more expensive than the original repair.

Get a copy of the Service Manual. I recommend Polaris' manual over the less expensive brands. You get what you pay for.

Visit NGK spark plug website: "www.ngk.com" Once the site opens, click "Spark Plug 4-1-1" link. Then click "Problem Plugs" from the left menu to view various plug images and what caused the condition to occur.

Visit "www.atvfrontier.com" to chat with other Polaris owners about ATV's.

Respectfully,
Mark Shively