When to know it's time for a rebuild
 

I have a '92 Fourtrax that I purchased used several years back. It starts and runs great and doesn't burn oil or smoke. It does seem to lack a little power when going uphill and seems to knock just a bit in such heavy load conditions. Should I just use higher octane gas?

What you look or listen for to know it's time to do a rebuild, even if it's just a top-end rebuild?

Thanks.

When to know it's time for a rebuild
 

Usually oil burning will be the tell tail sign.

The best way is to do a compression test and or leakdown test and see what the figures are and check them against book figures. This will tell the real story about how much blowby is getting by the piston.

If you are down on power and it does not smoke, it is possible that the valves are burnt or are hanging open and need to be adjusted? If you have not adjusted them in a while (or ever LOL), this is the first place I would go.

When to know it's time for a rebuild
 

Usually smoke and "out of the ordinary" noises are the pre-requisites for a top end overhaul - - Like Doc said, the leakdown test will tell you most as to where the biggest problem would be.

From what you state, a "tune up" with valve adjustment and clutch adjustment may be all you need; with the age of your quad, you may even consider a kit (new jets) in your carburetor as years of wear will reduce the effectiveness of the carburetor also. Kits can be found at places like Ebay for relatively inexpensive prices.

When to know it's time for a rebuild
 

I agree with Ujoint. I found out about my brother's quad, that was kinda doing the same thing, that all he needed was a valve adjustment and a good carb cleaning. Runs like a champ now. I would start there and see where that gets you.

When to know it's time for a rebuild
 

Thanks for all the feedback.

Yes, it's been a while since I adjusted the valves and suspect the carburator jets are original. As I said, it starts and runs great and doesn't smoke a bit.

Thanks again,

Dan