should i cut the air box???

5 replies to this topic
  • steed2

Posted April 08, 2007 - 03:37 PM


i was wondering how much of an improvement do you gain by cutting the side panel? Right now im uncorked, 180 main, hot cam stage 2, and fmf powercore 4 . Now the question im basically asking is does the power increase justify the added maintenance on the air filter?

  • XRR-kat

Posted April 08, 2007 - 03:48 PM


I do not understand how you can run a 180 main jet w/o opening the side cover!? Huge difference in flow!!
I was where you're at with 175 main, sea level, 30-40 deg, HRC tip and the opened side cover let the engine rev another 1,000 rpm....and I'm still too rich.


  • steed2

Posted April 08, 2007 - 04:11 PM


the 180 main gives better midrange pull...and actually the airbox would have no effect on the engine rpm limiter. the only way to get higher rpm is to change/modify the capactor discharge ignition unit. But i would imagine the airbox will give more mid-high end power increase.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • XRR-kat

Posted April 08, 2007 - 04:44 PM


What I'm trying to say is that I could not hit rev limiter without opening the air box side cover. The side cover venting gave me 1,000 more rpm but I still haven't bumped the 8,200 rpm limit!

I don't see the point of wringing it out if there's no power to be gained and I am geared 14/45.

More power is gained only by more flow, so more power is more air filter maintenance. If your primary concern is air filter maintenance, then tune and run at low rpms. Use the stock header, replace your hot cam with stock and keep it below 6K rpms. Kinda like a corked XR.

Maybe I should also ask what is your standard air filter maintenance?

  • steed2

Posted April 08, 2007 - 04:52 PM


i dont know about you but a stock corked up xr650r is like running an xr250 { to me at least} I clean my air filter every 8 hours of riding . {very sandy here}
Any ways i think were are both different type's of rider's and i dont want a muffled xr , but i appreciate your insight. P.S. if you couldnt hit the rev limiter before then there may be something wrong with your bike....a stock even corked bike will hit the limiter if you wring it

  • motopsycho650

Posted April 09, 2007 - 03:14 AM


I love the power gain. Enough extra air to run one sive bigger pilot & main jet. The cool thing is, I got the power gain without fuel economy loss.

The downside, like you said is cleaning the air filter. I have to now around every 150 miles. Less if I'm riding in a dusty area.

It's a little pricey, but I bought 2 TwinAir Powerflow kits, and 2 extra foams. I can swap filters anytime, even while camping, and then I just wait & clean all 4 filers at once.

Related Content


Engine Loping/Sputtering by tcaldwell

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 2 replies

2015 XR650L Squeaking noise by Crayjay

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 3 replies

Cle Elum Sunday 5/29: Looking for dual sport tips by TigerTanker

Dirt Bike   Dirt Bike Regional Discussion   Northwest
  • Hot  32 replies

ignitech programmable XR650L CDI by brianhare

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  57 replies

1993 XR600R rebuild by ove

Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  40 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.