2006 650, DJ kit, 150 main, 3 1/2 clip position, air box mod, ground header weld, stock exhaust.

So i live at 5300ft ASL, but this weekend went on a ride that dropped me down to about 3000ft ASL with an air temp of 105f+. 5th gear open the throttle and put the motor under load and i can hear the valves ping (pre-ignition):busted:

Any ideas?:thumbsup:

I'm thinking with the hot air temps and lower elevation i was running lean, because when i climbed back up and things cooled i could not duplicate it...:thumbsup:

Definately the altitude change will do that,just like my bike will load up if I go to a much higher altitude. 2000' isn't a huge change but enough to make a difference for sure. I'd go with 93 octane if you're planning the trip again sometime to see if that's enough to stop the pinging.

Yeah, i always run 91 (super) anyway, but i'm thinking about going to a 155 main or just raising the needle form 3 1/2 to 4th grove....

I was running that setup but needle 4th from top and my stock pipe is more restrictive.

Sounds too lean, I would either try different fuel an lower elevations or drop in the DJ155 main if you're spending any time down there.

If it's only temporarily, you could blank off the airbox mod a bit wth some duct tape. Say 50% of the hole.

Yeah, i switched fuel twice and had the same event...northern AZ has a lot of elevation changes and my ridding takes me from 3-7000 all the time, guess that's that part of where i ride...

Gotta agree with Max. Two minutes and a swatch of duct tape cure.

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