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Yz450f madness

Jetting

7 posts in this topic

I have a chance to trade my stock exhaust to an complete fmf titanium power bomb exhaust would I have jet my carb. It's off an 08 Yamaha yz450f and will be going on a 09 will it fit corectly. Thanks

08 and 09 will fit fine. The power bomb gets you some low end but loses top end. I run the 08-09 stock big header into the fmf on the rear.

You can also strip out all the baffles from your stock muffler and put a Pro Moto billet end cap on it. Then it is straight through just like the fmf rear section.

I tried a mega bomb and sold it right away.

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I have a chance to trade my stock exhaust to an complete fmf titanium power bomb exhaust would I have jet my carb. It's off an 08 Yamaha yz450f and will be going on a 09 will it fit corectly. Thanks

 

If you jetting is spot on right now, the new pipe will not require new jetting, but the top end may benefit from a larger main.

 

Too many other factors to create a single step answer...

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Okay thanks my friends for the answere. If I don't go with his exhaust what would be a good slip on for more bottom end torque.

 

If you currently have the stock exhaust, just about anything else will improve it.  Most typical aftermarket slip-ons will add between 4-7 whole horse power at about 5000 RPM (lower mid range) without affecting top end much one way or other.  The stock header is also oversize, but that doesn't matter as much as the restrictive muffler.

 

The problem with pulling the baffle cones out of the stock muffler is that they become rather too loud, and there's really no good in that.  As far as the power bomb , the purpose of them is to flatten the torque curve by making the header behave as if it has no defined length, which reduces the peak efficiency of the exhaust, but widens the range in which it is very effective.

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