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2004 wr450 jetting help

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hey guys... i have sifted thru all the jetting database and need a little insight.

First off.. my riding partner just bought an 04 wr450. The bike orignally came from cali, we bought in in colorado and was told it had been rejetted there.

We rode it last weekend in CO at 9 am 28 degrees and it ran ok..

We brought it home and got some stuff for it and pulled the carb to see what jets/needle it had.....

dwr needle... stock

45 pilot... stock

and it had no main jet in it ......

We are in amarillo tx... 3900' and temps are right now 60 ish. Fuel screw, stock, is a 1 3/4 out. We put a 165 main in it stock...

the bike starts great, idles great, pulls like a truck til half throttle and then it kinda spits and sputters. I have tried most clip positions on the needle and it runs best at the richest position. I have read that needle is pretty lean.

It has almost no decel pop, but really can't get it above half throttle.

any thoughts ??

thanks in advance


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Well, you must have an extremely dirty carb for it to run with no main jet. I would say that you have a very dirty carb, or a damaged carb. Time to remove it and inspect it closely. If you cannot get it to run past half throttle you have either a very clogged air cleaner or exhaust , or a very blocked main jet passage.

Pilot jet: idle to partial throttle

Slide: partial throttle and up slightly

Needle: the transitional portion from idle to partial

Main jet: half throttle to WOT

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try one smaller on the main, make sure the bike is warm to test all settings, maybe post in jetting forums to.

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