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dirtdevil96

Can anyone help me with jetting?

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I just installed a new full system exhaust and a K&N filter on my '07 Arctic Cat DVX400.It uses a Mikuni brand carb.I installed the recommended 150 main jet before I started it.(Stock is 130)I started the engine and the head pipe turned orange hot.Is this a sign of too rich?Should I go to a lower size main jet or is there another adjustment/jet that needs changed?

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actaually for most aftermarket exhaust on 4 strokes the head pipe will turn cherry red...ive heard this b4 not a big dealsigns of running rich or lean will be backfiring...

rich will backfire out the exhaust pipe and lean will backfire out of the carb/airbox...hope that helps.. if your bike isnt backfiring id say your fine...

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I think I found out why it's turning colors.I didn't adjust the fuel mixture screw.On my quad;there's a cap I have to remove(damn you EPA lol)to be able to access the mixture screw.I was told by the exhaust manufacturer that I would only have to rejet the main(they never said anything about the mix screw).I sent a message to Dynojet and they said to get the most power I need to change the needle also.They've been MUCH more helpful than the manufacturer(they even have a Q&A forum-what a waste of my time that was!!).So I think I'm gonna order the Dynojet kit and maybe a couple more things while I'm at it.Thanks to all who replied...

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