winter to summer jetting?

[jeremy_283]

Do you need to change the main jet when winter turns to summer?

[Sjorge450R]

Originally posted by extremejrowe
Do you need to change the main jet when winter turns to summer?

I did. I went from like a 120 DJ to a 128 over a 40 degree change.

[GPracer2500]

If you want to keep your jetting spot-on, then YES. Typically the pilot jet and the needle are less sensitve to air density changes (hot vs. cold and high vs. low). All three carb circuits can be tweaked, but the main usually benefits the most from an adjustment for tempurature changes.

The bigger the temp change the more benefit from a re-jet.


As a side note, the smaller the displacement of an engine the more sensitive it will be to air density changes (i.e. a 300cc engine needs more jetting changes than a 700cc engine to keep it running well under changed atmospheric conditions).

[DaleJrFan]

Like GPR2500 said but the huge swings in humidity and and we get alot of really dry air make a difference too. If I dont keep my packing in good shape, then I run real lean and have to change my jetting to run a little richer.