Home. Back. ...... The Gas Gas Guru. Technical Information.
Hello Jon,

I just moved from New Mexico (where I rode at altitudes from 7,000 to 11,000 feet) to Iowa where I will be riding at a few hundred feet above sea level. My 1997 Gas Gas 270 has always been jetted for high altitude. What jet(s) should I install for sea level operation?




I can give you all the Physics and Fluid Dynamics explanations as to what jets you might need, however, a call to your local Gas-Gas Dealer will probably get you the correct jets in a lot less time. A general rule of thumb is to decrease one jet size for each 2K of altitude. You may not need to rejet the pilot depending on other atmospheric factors.

Some other considerations:

Lower Ambient Temperature= denser air= richer jetting

Lower Relative Humidity= denser air= richer jetting

I'm going to attach an article on jetting I did for Trials Comp News that might help you to fine tune the carb.


Professional tuner and 'Trials Competition' writer Jon Stoodley has very kindly stepped up to the plate to answer your questions. If you're having problems, or need some advice just send an email to Jon. If it's something that could be useful to others, we'll post it on the site.
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