Airbox Cutout w/ Edelbrock QS? Any changes?

3 replies to this topic
  • J_T

Posted December 04, 2003 - 08:39 AM


Now that I know what I am going to do with my supension thanks to Bruce I am curious about the Airbox Cutout mod w/ Edelbrock QS? I live at 300-1000 ft msl and have a Edelbrock QS that I bought from and it runs great right out of the box!

I am curious what I will notice if I did do the airbox cutout?
Would I need to change anything on the QS carb?
Would by opening up the flow if I'd loose any of my low end torque? (I ride woods so I enjoy the response and torque more than the top-end)
I'm brainstorming here b/c I like to work on my bike and I can do this mod with little cost. I'm not sure I am yet b/c I do ride in wet conditions and water crossing so I may wait until I have an extra cover but my riding locations should be dry until late spring when they raise the lake level so I'd like to now if I find its benificial for my style!

Thanks in advance


  • qadsan

Posted December 04, 2003 - 09:03 AM


You may have to turn the mixture adjuster screw on top of the carb a few clicks richer, but that's all I did. You can also ask Rob Barnum and he can give you the straight scoop.

On a stock uncorked XR650R, this mod will increase the HP from ~4,250 RPM on up and improve the torque from ~3,750 RPM on up without sacraficing anything on the low side from what I've seen in dyno printouts. The negative issues from doing this mod is that you'll hear more intake noise, you'll be more subject to getting the filter wet since the side panel will be open and your filter will get dirtier quicker. It's a win win for me cause I've got two side covers, one modified and one stock just incase, but I ride with the cut out side panel 99% of the time :)

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  • J_T

Posted December 04, 2003 - 12:29 PM


That sounds good. I didn't know if a richer needle would be needed or not. Inrichening the setting like that is simple. I figured Rob Barnum would know but I also know he sells the cutout covers so I hated to ask him when I would like to just cut my own. I certainly would if I was buying one of his. Thanks Quadsan


  • qadsan

Posted December 04, 2003 - 03:41 PM


If you're needle is already cranked pretty far to the rich end, then yes, a new richer needle would probably be a better choice. There's a lot of overlap in the needles, so if you're already somewhere in the middle, then it probably won't be much of an issue. Changing the needle is pretty simple if you do have to do it, but make certain to do correctly or call Rob if you have questions because there's a loc-tited star screw in that assembly that some people mistakenly try to remove and end up breaking their star tool or damaging the part. That one particular screw has the type of loc-tite on it that requires heat from a torch to loosen it, but again, you don't need to remove that screw to change the needle.

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