ORIGINAL: Lewis.
ORIGINAL: 1QwkSport2.5r
ORIGINAL: Lewis.
I was talking 16% like this:
http://www.modelsport.co.uk/modelspo...products/29346
The manual for my Firestorm recommends 25% but it seemed a nightmare to tune on that. Kept cutting out and wouldn't start for ****. I have read loads so figure I am pretty clued up. Is it easier to tune the car when running a lower percentage of nitro?
thanks again guys
More nitro is easier to tune and adds power. If it revs slow and really smokey, its too rich. If it cuts out its too lean. The idle needle controls fuel mixture from idle to about 3/4 throttle, and the main needle (high speed) controls that last 3/4-WOT bit. Richen your low speed mixture a 1/4 turn or so and run a WOT pass or two to get the main needle set, then set your idle. Never set it the other way around.
Going from 16% nitro to 25% nitro would probably need the needles richened 1/4-1/2 turn to compensate for the extra nitro. More nitro = richer needles.
Hi mate,
That's excellent thanks. So when you say the idle needle, you mean the idle needle and not the LSN (low speed needle?) Just checking - thanks for your help again!
When I speak of a "needle" I mean mixture needle. Most often, car guys call it the low speed needle though its the idle/midrange mixture adjustment. The main needle, or aka the needle valve is the "high speed mixture needle". The idle speed adjustment (controls idle speed, not mixture) isnt a needle, it just controls how far open the carb's slide or barrel is. The idle speed adjustment will effect idle/midrange fuel mixture. If you drop the idle rpm, you will in effect lean the idle mixture. If the idle rpm is changed, the idle mixture needle will probably need to be adjusted a little to compensate.
The high speed or main mixture needle is in a fixed seat, unlike the idle needle. For this reason the main needle is always set first, and idle second. Some carburetors will not take a proper setting if the idle rpm is too high. Most of the time, low rpm mixture problems come from too high of an idle speed. Shoot for a idle gap of 1.0mm or slightly less.