06 yz450f jetting question

my 06 yz450f has all the stock jetting and needle clip position

it has a 13:5:1 piston and a DMC exhaust, boyesen accelerator pump cover. i live in arizona so its very hot and dry.

what should i do to change the jetting, i believe its running lean. misses at full throttle.

any help would be great thanks everyone

it should have no wot throttle issues with stock jetting.

does it rev fien then suddenly start to miss fire?

i pulled the plug and it looks like it just came out of the package. no soot or anything.

i rode for an hour with no problems, then on my way back home i got on it and it stumbled like it was running out of gas, but there was plenty.

how should i jet it for the mods?


thats the way the plug should look.

i would check your a gas cap vent.

i noticed that the fuel hose was touching the cam cover, the fuel hose is clear and i saw bubbles coming up.

the stock jetting should be fine for high compression? j/w i want to make sure its tuned right

close enough that its not causing your issue.

thank you Eddie, uill fix the hose and go out and try it again


I have read many posts on the '06 YZ450 and the appropriate jetting; just so I am clear, what is it?!

My current: 48/170, stck needle/clip, FS @ 2.5, Boyeseen QSA, FMF Megabomb. I have not had it on the track yet, but it seems to blast up & down the street w/ no hesitation on snapping the throttle in neutral.

Prior was the stock 42/165 - bad decel popping and bogging when revving.

I've read that the 45/165 is also good (warmer weather)? I'm in SoCal; anywhere from 500~2200 elev.


you can definatley go 45/168 easily in the heat.

Hi mate

could it be the airfilter? Bubbles are not too bad as long as they are not staying 'till the Swimmer chamber. Warm Gasoline gets a better Gas mixture I believe.



no it was the fuel heating up in the fuel hose, i noticed it was spitting gas out of the fuel tank vent, fixed the hose and now it seems to be ok

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