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Discussion Starter · #1 ·
I want to run my prox on the grass once in 500 feet race at about 700-1000 alt

v-force 3, slp airbox horn and clutched all else stock what would be a good jetting for these temps about 70 :beer:
 

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390 should be fine for 500' pulls at 70*. The dyno sheets I have looked at 390 was on edge at 55* so it should be fine at 70*. Even with 390 at 55* a average dyno pull is 8~10 seconds at WOT theres didnt burn down but the air to fuel ratio was way to close to the line . I say no worries just go for it!
 

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You're not getting many replies cause you're asking how many times should you pull the trigger with 3 rds in the gun next to your head.

YOUR sled at YOUR elevation at YOUR rad on YOUR motor clutched and geared by YOU.
All these factors are important, particularily when you are asking " How lean can I go?"
I am hesitant to offer this kind of advice even when solicited.
If you're goin drag racin you should have a handle on calculating the above variables with enough certainty/confidence to get a starting point and then test/test/test/test until it's fast enough or it squeeks....whichever comes 1st if you want to win!

Not tryin to preach.........answerin the question posed/posted.

With all that said......that setup is safe @ 420 mains around 0deg F.
The mikuni slide calculator will show you how lean to go for temp drop but Relative Air Density is affected by more than just temp so be careful.
The suggestion of 390 is prolly about right ( I would go leaner but that's me).

Also. Jetting lean will provide a few more HP and sharpen up the launch BUT the real ticket to makin your trail sled work well at the grass drags is to load the clutches heavy and gear it right. It's a short race and you need 0 backshift so you can load way harder than a trail setup.

Hope this helps.......good luck.
 

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Originally posted by terez@Oct 3 2005, 04:56 PM
You're not getting many replies cause you're asking how many times should you pull the trigger with 3 rds in the gun next to your head.

YOUR sled at YOUR elevation at YOUR rad on YOUR motor clutched and geared by YOU.
All these factors are important, particularily when you are asking " How lean can I go?"
I am hesitant to offer this kind of advice even when solicited.
If you're goin drag racin you should have a handle on calculating the above variables with enough certainty/confidence to get a starting point and then test/test/test/test until it's fast enough or it squeeks....whichever comes 1st if you want to win!

Not tryin to preach.........answerin the question posed/posted.

With all that said......that setup is safe @ 420 mains around 0deg F.
The mikuni slide calculator will show you how lean to go for temp drop but Relative Air Density is affected by more than just temp so be careful.
The suggestion of 390 is prolly about right ( I would go leaner but that's me).

Also.  Jetting lean will provide a few more HP and sharpen up the launch BUT the real ticket to makin your trail sled work well at the grass drags is to load the clutches heavy and gear it right.  It's a short race and you need 0 backshift so you can load way harder than a trail setup.

Hope this helps.......good luck.
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I agree 100%
 

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Discussion Starter · #7 ·
Thanks guys with the 390's should I leave the needle in the stock position? or can I com down one? :beer:
 
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