[/quote]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.