Originally Posted by
Dirtdobber
I'm kinda like you,I only have 2.5 gallons through mine. I finally got to race it a few weekends ago and used the 6.5mm insert which was good while the track was dry. My tune was changing a lot(may be AE fuel tank,gonna try xray tank on next outting) and right before the main it rained and made the track muddy. About 3 minutes into the main I overheated and died. After changing plugs and richening the main, I got back into the race but my engine was very weak on bottom(like too lean) and the main was very rich. I gonna try the xray tank and start with the 8mm insert on my next visit to the track. My needles are about the same as yours. I run 25% fuel and had the odonnell 77t plug in. I'm thinking the 6.5mm insert and the muddy track was most of my problem. Thanks for the info.
mud does not promote a well running engine
base needle settings for fms - 4.75-5 turns out on low speed , 3.5-3.75 turns out on high speed , close idle gap until it just closes (insert out) and reopen .75 - 1 turn.
this will get you a little rich of race tune and remember these engines need more fuel on low speed ( richer setting )
you know your fuel delivery system is right when your engine runs consistant , if the engine runs erratic then you need to inspect and fix as necessary
hope this helps and happy motorin',
monty