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JD jet/needle kit set-up for YFZ450

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Looking to make sure I am choosing the proper needle and jets for Michigan racing. I installed the red needle on clip 4 and put in the 45PJ and recommeneded MJ (I think it was a 165).

It seems to run good, but has some minor popping on decel. I have a 3 hr race on Saturday and want to make sure I set up the proper needle.

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To reduce the popping on your YFZ450 (quad), the red needle can be used 1 step richer (#5 position) or switching to the blue marked needle in the #3 position will help. These should be very good settings with the #45 PJ.

The next step would be to go with blue #4 and/or a #48PJ, as Indy suggested.

Thanks,

James

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Do I have to worry about meltdown running the red in pos 4 with a 45PJ for the 60-70 degree temps at sealevel, or am I just going to get some popping? Changing out tonight is not a preference unless I stay up all night prior to traveling to the race. If I am going to chance engine damage, then, i will make mods.

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Forgot to mention this is the YFZ450 ATV/Quad and is a completely stock motor and exhaust set-up. Is the blue in clip 4 and 48PJ still good?

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Forgot to mention this is the YFZ450 ATV/Quad and is a completely stock motor and exhaust set-up. Is the blue in clip 4 and 48PJ still good?

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Nothing to worry about in regards to red #4 and #45PJ, the jetting with red #4 is still richer than stock and should not cause problems. The YFZ should run slightly cooler than stock.

James

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Like JD says you wont blow it up but if you are lean she will not pull as hard! You have to try both jettings and see which pulls better. :thumbsup:

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