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rengland

The best jetting kit to purchase

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I am going to rejet my 03 YZ450F and curious of what's the best jet kit to install? My riding areas range from 2,000ft to 7,000ft and temps between 55-95 throughout the year. I currently installed a FMF powercore 4 exhaust so should I install a FMF jet kit? Currently everything else is stock.

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Hey rengland. I have a 01 YZ426 and just got a FMF Powercore 4 for xmas that I haven't put on yet. I was curious did you put your powercore on your 450 without jetting? Did you adjust the main jet at all? Reason I'm asking cause I would love to install my exhaust but I don't have any jets and when it comes to bikes, instead of cars, I'm a total noob.

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Have either of you looked at the second link I posted yet?

 

With any of the YZ400F, 426, or YZ450F models, the stock exhaust is really a pretty good system to begin with.  80% of the time or better, it's unnecessary to rejet when you replace the stock pipe with a well designed aftermarket one unless the jetting was wrong in the first place.

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FWIW I bought the JD jet kit with high expectations and was disappointed.  I wouldn't spend the money again.

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Actually I had this page up overnight and replied this morning without refreshing so I didn't see your post. Sorry. I'll check out the links in your post now. Apparently the previous owner completely removed all the innards from the the muffler so it's WAY too loud for my taste. Especially since I'm plated and don't want to piss off my neighbors every time I'm riding through my development to go out on the roads. The exhaust has seen better days also so I definitely wanted to replace it. Reading what you said I think I'm definitely going to do the install today. Just picked up some Hi-Temp silicon from Advanced Auto so I should be good to go. As far as adjusting the carb, as I mentioned above, I literally have no idea where to start. I'm trying to find someone experienced that's local to me that wouldn't mind hanging out and showing me a thing or two. I have a lot of parts picked out but haven't ordered them yet because I'm unsure of how to do the installs and don't really want to pay the local motorcycle dealer I use and pay an arm and a leg. Anyways thanks for your response grayracer513.

Edited by gameraddikted

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Hey rengland. I have a 01 YZ426 and just got a FMF Powercore 4 for xmas that I haven't put on yet. I was curious did you put your powercore on your 450 without jetting? Did you adjust the main jet at all? Reason I'm asking cause I would love to install my exhaust but I don't have any jets and when it comes to bikes, instead of cars, I'm a total noob.

Yeah, I put the powercore 4 on before jetting. My next step will be jetting I just got to figure out what size jets to install. Good luck and keep me posted how it turned out for you.

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