Racing up in elevation

Being from Michigan, I haven't really had to deal with this issue much.  There's a race coming up in a couple weeks in a city with an elevation of about 5000 feet.  I currently ride at about 2600 feet and my bike runs great.  (maybe a touch lean when it gets cooler, but not enough to worry)

  Do any of you guys bring extra jets with you just in case?  If so, what do you think..should I just bring a slightly leaner pilot and main.  Or should it be just fine.  I don't want to drive 5 hours just to have my bike run like a turd.  Nor do I really feel like tinkering the morning of raceday. 


It's a 250 with a big bore kit (280) running on VP110 and mixed at 32:1 if that helps.  I looked at the jetting page a bit, but couldn't really find a great answer.  Any input would be appreciated.  Thanks dudes.

I ride at places between 850-4000' without ill effect. The weather is relatively similar between altitudes, which may not be the case for you.

Setup: Stock bore and comp, 100LL, 40:1, 172 main, N3ew needle, std timing, DEP/PC 296 SA, Boyesen Rad valve

There is a carburettor that you can buy with external adjusters. I am able to change the main jet easily by tilting the carburettor with the tank in place. Needle clip position adjustment is not quite so easy.

You may wish to post your jets, wash, spooge, plug pics and VP fuel type to ensure you're in the ballpark at 2600 feet. Obviously, a rich condition will be compounded (all other things being equal).

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now