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AndrewBriscoe

need jetting help

mysledblows

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Nov 26, 2007
463
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Minnesota
When I ran my 600 twin I found that it liked 140's or 137.5's at that altitude. I think if I'd have had the yamaha jet that's half way in between it would have been perfect as the 137.5 were a bit lean when it would cool of a lot during the day. Needles in the top clip with one washer under. Pilots were 55's I think. Obviously if your temps are real extreme one way or the other you'll need to tweak things, but this should get you close.
 

snowdad4

Active member
Nov 26, 2007
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southeast washington state
try the 138.8. 52.5 on the pilots. lighten up the tip weight on your cam arms, use the aluminum 2.7 gram rivets in both holes, if your running 8CR weights. shoot for a 2:1 ratio on gearing, 20/39. scott
 

clharris

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Nov 29, 2007
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mantorville mn
thanks for the help,how about the air screw?, I put on a ATTAC kit but thinking I should take along jets if it dosnt work right
 

mysledblows

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Nov 26, 2007
463
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Fuel screw I think was 1.5 turns out, but that will depend on your motor as it's a fine adjustment to get perfect.

Clutching I ran the 8 CR's with a 3.6 in each hole. Doing it again I'd run a 2.7 in the tip as I was just under on my rpm's. Y-S-Y short spring seems to ring a bell. May have been a G-P-G. It's been a few years and my notes are at home. I ran a either a 45 or 43 helix/ green spring @ 70.
 

clharris

New member
Premium Member
Nov 29, 2007
226
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mantorville mn
thanks for the help ,hoping the ATTAC system work good out there, leaving in the morning & staying @ snowy mountain lodge for the week , sure hope they have some good snow