Bored Edelbrock carb??

4 replies to this topic
  • krokodilen

Posted December 21, 2007 - 11:08 AM


Fully bored what does that mean. And how?

/ Christer

  • Denn10

Posted December 21, 2007 - 01:28 PM


prolly someones had it bored to make it bigger, on an empty carb they bore thru the passage where the air goes through. kinda like this pic going straight thru it


you can make a carb 1mm larger to get more air flow, not used alot these days i dont think like i remember back a while

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  • weskc35k

Posted December 21, 2007 - 02:42 PM


Some carbs get what is called "keyhole' bored for more top end power.
Not sure if this is what is done to the Eddy.

  • HawkGT

Posted December 21, 2007 - 05:56 PM


Generally, a bored carb has its throat machined to a larger diameter. Bored FCR's are not unusual in the ATV world. They can be straight bored or taper bored. A few mm larger is all you can do without replacing the center ring with an aftermarket unit that has more meat on it. That limitation is specific to FCR's though. Other carbs will have their own boring limitations.

I'd contact Edelbrock directly about getting that carb bored. I believe I've heard that they do (or did) offer boring services for their carbs.

  • BWB63

Posted December 25, 2007 - 07:57 PM


The Edelbrock has an oval, 36mm wide and 42mm tall venturi. It is not like the other almost round carburetor venturi. They have a few different edelbrock bodies and can bore these bigger for use on different bikes. The 36mmX42mm is the basic large body used on the big bikes and is bored bigger for some of the hot rod harley's. The Edelbrock that is used on the XR650R was first made for Harley's as was the Mikuni TM40 and HSR 42, 45, 48 series Mikuni's. The 36mmX42mm runs to be about the same as a 39mm carb. and can be bored to a little over 40mmX42mm. Mine was bored using the 40mm bore but, move a little on mill and reads about 41mm X 42mm. This is a whole different animal once on a XR650R for mid to wide open throttle. It takes about 5~10 minutes to strip the carb. and about that to put it back to gether. At Edelbrock on the first bore job they did, it took less then 15 minutes. They were already setup with a 40mm bore in the mill. They pulled the slide, squirt jet out with needle nose and the needle jet. Put the carb. in a jig that was all ready and bored the throat. Put it back to gether and adjusted the squirt jet to squirt right and back on the bike. Anyone that has bored something can bore this carburetor. They did four Edelbrock's for free then I think it was Mr. Lewis that got charged first, David Gray or Rich Tracy was next to get charged. It wasn't much but, I haven't had it done in a little over a year now. I wouldn't call, because you won't be dealing with the guys in the shop that do the work. I have always drove right to the motorcyle carburetor shop at the North end, walked into the east door and stood there till someone asked what I was doing there. The guys are so helpfull they loved a little change in the day and I walked out with a bored carburetor.

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