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426beastlover

426 carb issues

12 posts in this topic

i just rebuilt my carb on my 426 because it was so dam hard to start i found that one of the jets was clogged so i cleaned it out and found that the bike starts up no problem now. i issue that im having is i let the bike warm up on idle, and when i give it some gas it revs up and dose not want to come back down. i can shut the bike off and restart it and it will idle fine till i give it some gas then it just stays up there. i need some help and suggestions would help.. thanks...

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thanks the next thing im going to do to the bike is the cam swap and have the valves checked out at the same time thanks for the reply

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"seems like the most common jetting issue that comes up are pilot circuit related.the following is a sure method to choose the needed changes.

with the bike warm and idleing turn the fuel screw in till the idle drops/misses.then go back out till the idle peaks/smooths.

this should happen between 1 and 2.5 turns on a fcr carb and 1 and 3 turns on a cv.

if you end up at less than 1 turn you need a smaller pilot jet.more than 2.5 (or 3 turns on a cv) you need a bigger pilot jet.

choose the appropriate size and retest."

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Did you install the Needle Valve in the correct orientation? It's that plate thingy on the front of the slide. The hole goes on the bottom. See part #11 http://www.apachemotorcycles.com/fiche_section_detail.asp?section=39247&category=Motorcycles&make=YAMAHA&year=2001&fveh=1038

I installed that upside down once on my YZ426F and that caused a hanging idle.

Edited by Dave102429
F

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i dont think that i took all that off i just pulled the crab and cleaned the jets. but i will check that and thanks every on the info i got i should be able to figure it out and thanks for the links they will help a lot tanks again

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well i just did everything that everyone suggested to no avail. the bike it doing the same thing i let it warm up and the idle is nice and strong but the moment i give it gas the bike revs up and never drops i did change the oil and found some metal shavings in the oil filter so of to the shop the bike goes

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