w muller

Yesterday I was out sledding on fresh snow in a very open area at about 8000 ft elev. I have a 95 vmax 500. I’ve been experimenting with main jets. I normally don’t run it to hard and the jets seamed fine. But yesterday I ran it hard for some time. After it got up in RPM it seamed to flatten out. So I shut it down and checked the plugs. They were white, very lean. I have it jetted to the chart in the owner’s manual. I also have a pipe on it. Any one have an idea how much I should go up on the jets?

spaz _head

Usually the jetting chart is for stock exhaust. You may want to go up one or two jet sizes for aftermarket exhaust. Remember that main jets only effect throttle position of about 3/4 to full throttle.
If you don't run the sled hard your jetting was fine, but when you ran it hard the lean condition started. Fatten up the mains, better to run a bit rich than lean. You can also install a Variflow and be able to adjust the jetting on a remote dial. They work great.

Lster

spaz _head

One other thing I forgot. If the jets are dirty (waxy build up) they will actually be smaller causing the lean condition. Even the slightest dirt will change the jetting. I usually change the jets every year with new ones. They are cheap.

Later

kccats

Most people say that a good single pipe will work better than twin pipes for the mountains? I don't understand why but? Jetting acording to the chart, with pipes is looking for disaster! You may be too late! Put a very little bit of wd40 in the cyl and do a compresion test with the throtle wide open? See if you are over 120? You maybe at 100? The other thing most guys don't remember when they put on pipes is the intake? More air out doesn't mean more in?