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White08yz

08 yz450 exhaust jetting help

10 posts in this topic

I have a 08 yz450 I put the pro circuit ti-4 full exhaust on all I did is put a 162 main jet cause I didn't want to run lean and it runs great but pops on decel can you help me out? What can I do is it normal for some popping?

I just don't want to run lean or mess the bike up it runs great besides the popping any help is appreciated

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Thanks for the reply I will try that stock is 45 so 48 would be the next size?

How do I tell if its lean just by reading the plug for the main jet anyways?

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Do not just go up one size without reading the links I posted. Reading the plug is a waste of time. Tells you nothing, really.

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Is mine a fcr carb or cv

It's an FCR-MX.

And also how do I know if the main jet is lean?

Read the third link, 3-4 lines down.

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I was messing with the bike more and when I rev it kind of high just on the stand it will shoot a flame out

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What happens on the stand has little or nothing to do with how it works when you ride it. A certain amount of popping on decel is normal if the bike is jetted right, as the post I linked you to first points out. But, as it also says, the popping can be caused by air leaks in the exhaust , too.

Adjust your pilot according to the second link. That will tell you whether the jet is the right size. Then, if it still pops, check the exhaust joints.

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