Jetting For Altitude

[Hefe4Pres]

I jsut recently put on some new PC pipes. What type of jets should i be running?

 

The Stats:

 

2001

Pro Circuit w/ stock silencers

K&N Filter no lid

run at 6,500-8,000 ft

[sredish]

I'd probably start out with:

 

280 main

stock pilot

3rd clip on the needle

 

That is a "guesstimate" and you'll have to do some plug reading to dial it right in.

[sand rocket]

I run about the same altitude as you are and i melted a piston running 290s. Start the same a Sredish said in his post, but bump the mains to 310. It will probly be a little rich. But better to be rich than lean.

[ledofthezep]

I run about the same altitude as you are and i melted a piston running 290s. Start the same a Sredish said in his post, but bump the mains to 310. It will probly be a little rich. But better to be rich than lean.

That's what I say...always better to be rich. I'm running 280's in my shee at about 300' above sea level, and I have a few more motor mods than you do...I'd agree with sand rocket & start out at about 310 and work your way down if necessary. 280's might be right afterall...

[Hefe4Pres]

Well the one thing i do know is that you need to run lean. Less air = less gas.

i just need to know if there is some ratio for jetting for altitude. For example, decrease one jet size for every 1,000 feet. Hear people talk about it but no one that i know, knows the ratio for 2 cycles.