is it possible

[acrtheone]

I just bought a 04 yfz 450 and it has a hmf slip on and a k&n air filter and it has not been jetted. the kid did not have enough time but i got the jets that came with the pipe and i was wondering if i could change the jets without taking off the carb. I want to do it as quick and easy as possible.

[ohsobad_chevy]

You can get to the main and the pilot without taking the carb off, but you will probably need to adjust your needle and fuel screw as well. You can buy an aftermarket fuel screw that you can adjust "on the fly." which I definately recommend.

To get to the main and pilot, just loosen the carbs connections on both sides and rotate it gently. Size 16mm I believe. ;)

[acrtheone]

thanks for the tip i will try that out

[hotrodbelair]

its a 17mm or at least mine is

[#17YFZRACER]

i always take mine off, its easy after you do it a few times. :ermm:

[Toadz400]

Loosen up the carb and tilt it sideways. 17mm plug on the bottom reveals the main and pilot. Let us know what's in there, never know if it's still stock or not. As for the needle I tilt the carb, take the seat off, and go at it from there. Just take a look at it and figure out a way that you could get the top off and at the needle. Once you find an easy access point it's very simple to do. I used to be able to adjust my needle and main jet almost as quickly as I could on my 400EX.

[acrtheone]

i think i am just going to take the carb off and just do it that way because i have never done it before and i dont want to mess anything up.

Is it easy to adjust the needle? any special tools?

[ohsobad_chevy]

Nope, just pull the needle out carefully and you will see a clip where you can raise (richer) or lower (leaner) the clip position.
Let us know if you encounter any problems and we will help you through it.

[Toadz400]

It's easier to screw stuff up taking the carb off than just tilting it, but to each his own.

As for the needle. Just take the top cover off the carb then slowly push the throttle all the way open. While holding the throttle wide open grab the clip. Raising the clip will produce a leaner mixture. Lowering the clip will produce a richer mixture.

[acrtheone]

I took the carb apart and installed the 48 piolet jet and 170 main jet
by accident i took out the piolet screw and did not know amount of turns on it but i called a dealership and got squared away.
The clip on the needle was at the lowest position when i checked it, so i left it , not shure weather it was a good idea or not.
Have not got a chance to run it yet but i hope it works, going to try tomorrow

[acrtheone]

hey i have a quick question,
the pilot screw that is on the bottom front of the carb is that the fuel/air screw?
I was looking at aftermarket fuel screws for easy adjustment, is that what it replaces?

[ohsobad_chevy]

Yes, they replace the factory screw and they hand down to where you can adjust it while the engine is running. I highly recommend you getting one, they are very handy and make tuning much much easier. ;)

[acrtheone]

i think i am going to get one thanks