You may want to get some input from guys that have the FMF PowerBomb on a bike that is running properly.
More power across the entire RPM range, quicker reving and able to pull 10,000rpm's with ease.
It's worth the money unless you're tight on cash.

 

i switched the fromt the race core to the quiet core in the BG, and it revs faster... i bounced it off the rev limiter in 3rd.... runs alot better with that quiet core, and not that vortex insert.

 

Sorry i did forget to mention that I 'm running without the lid on the airbox. I did run it yesterday with and without the lid and it defiantly ran better without. It won't pull to 10k rpm....stop's pulling hard at about 8k to 9k. Close enough? I haven't had the time to really get it dialed in and probably won't for another couple of months unfortunately. Work always seems to get in the way of everything! I do like the fact that the FMF is on the quiet side though...I'm very pleased with it so far. As is, the bike is 10x better than stock.

 

If you have the FMF PowerBomb header and Q4 pipe and it won't rev up to the limiter (in the first 3 or 4 gears) fairly easily then you have some other issues that need to be resolved.

 

Did the Powerbomb add more to the end or bottom end for you?

 

It didn't hurt my bottom end at all but also didn't add much power below 4,000rpm's but I never ride in that range anyhow, the engine now progressively rev's better from 4K on up and also allows the use of the rev band above 8,500rpms which the engine would pretty much not rev over in stock from and even if you did hold it pegged long enough to get it over 9k there was no power to be gained by doing so.

 

With the airbox lid completely off, you can probably get away with a 132 main. I would play around and see what it does with the 128 and just the snorkel removed first.

Any backfiring? l meana loud BANG, not the the mild popping during compression breaking. If so, make sure the vacuumnipple on thecarb is hooked-upto thesmog gearvacuum line.

 

128 main, and snorkel removed, lid still on, is what i run, and it runs great.

 

No backfiring at all. I still need to loose the smog crap though. From what I heard that is the reason for my deceal popping and discoloring of that nice stainless header!. I used a DJ kit and followed their directions as far as main jet size. What would I gain by going to a larger jet? (sorry for the dumb question!) I'm still trying to squeeze the best fuel mileage as possible. I'm not sure i want to tackle putting the Clarke tank on just yet. That could be next winter's big mod.

 

yep ems, that was what I use to run on my KLX with my BigGun full and it would bounce off the rev limiter all day long. There was no "stop pulling" before 10,000 rpms. I enlarged my snorkel hole but left the lid on. I once tried it w/o the lid and it wouldn't rev hardly at all. I think some of these newer guys think there is a benefit of running with no lid, but it seems like every story I read of someone trying it turns out to be a week long of trying to dial the bike in until they realize that once they put the lid back on it cured the problem. Just enlarging the snorkel hole is the key I think. The "3x3" airbox mod is common on any DRZ which means enlarging the snorkel hole on top of the airbox and rejetting, it works the same for the KLX.