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jaybert600

Edelbrock Question

14 posts in this topic

While on a ride Friday, I had a small problem with my Edelbrock equipped XR650R. The engine seemed to "load up" during slower sections (where the throttle was constantly on-off), causing me to "clear it out." The bike runs fine in all other conditions. My question is, could it be to rich (needle adjustment), or could it be something with accelerator pump? Any ideas would help!

Thanks,

Jay

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if it was running fine -- i.e. correctly tuned -- before, and you didnt make any changes to the airbox/pipe/motor....then its not likely to be the adjustments.

once its adjusted-the carb shouldnt need re-adjustments.

the fact that you developed this problem on one ride suggests something went wrong, as opposed to something is wearing out (like the pumper, for example)

there are lots of things that can cause what you describe, from dirty gas to ignition to water in the plug cap to leaking manifolds to a frayed throttle cable to a gummed up needle valve in the edelbrock. ..etc.etc.

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If I were you, I'd take the Q.S. off, open it up and clean it out. Take the pumper assembly out too, dirt can get in there as well. I had so much crud in there once that it wasn't allowing the pump to move nicely and it actually broke the pump! The first time I cleaned my Q.S., an entire sandbox poured outta it.

Geoff

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Sounds like you have to much pump. Turn it out a full turn and see if that helps.

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Sounds like you have to much pump. Turn it out a full turn and see if that helps.

Frogman agrees!

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Sounds like you have to much pump. Turn it out a full turn and see if that helps.

That is the direction that I was thinking, since it does in fact clear out.

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*Update*

Tonight I pulled the carb off just to check it out. Pulled both the float-bowl and the accelerator pump. Both were spotless (except for a small amount of corrosion on the accelerator pump spring- no big deal). So I reassembled it, adjusted to 12 clicks out on the needle (17E), and another 1/2 turn out on the "squirt" adjustment (which is now awfully close to the head-pipe). Next weekend will be the test. Thanks to all for the help!

Jay

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Jay,

You can adjust the pump squirt with the engine still running if you're careful. If you're not happy with the off-idle performance, just loosen the lock nut while holding the pump adjustment screw with a screw driver so it doesn't move. Then turn the pump screw 1/4 turn in the direction you think it needs to go, hold the screw in place with the screwdriver, then tighten the locknut and go for a ride. For me, I've found my carbs had too much squirt and I ended up turning them down. Once you find the range where the off idle performance is getting really good, tune it in 1/8 turn increments until you find that sweet spot where you get crisp off idle snap wheelies. What's really odd to me is that my older carbs have a much different pump setting than my newer carb does. I guess Edelbrock made a change somewhere along the way???

In anycase, it's nice to have an external pump adjustment as opposed to having to take the carb apart to change out leak jets, pump diaphragms, drill & tap the carb for a set screw to set pump timing, etc, as with other bikes.

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Wow, that's another new change. When I bought my first Edelbrock , it came with a 17E needle and came with 15 & 19 as spares. Later on, my other Edelbrock came with a 19 as stock as 17 & 21 as spares from what I recall. For my first carb, I tried various needles and found the 18 to be the best for my bike and for where I was riding, but I had to buy that as an option. There's a lot of overlap in the needles, so you can tune one carb to be very similar to another in much of the performance range even if they have different needles just by having them set a half dozen or so clicks apart. In my carbs that came stock with the 19 needle, I just left that needle in and ran it a number of clicks leaner than my carb that has the 18 needle. Performance is similar, but I got better top end performance with the 18 needle without loosing any mid range when I was running the stock exhaust with the HRC tip. With the Moriwaki exhaust and my airbox opened up, the 19 needle may be the better choice, but I haven't got around swapping needles again on that bike to find out if the 19 would benefit me on that particular bike. If you got an 18 needle, then that's great IMO because that was my favorite needle for one of my bikes. The 17 & 19 also worked well once I dialed them in, but I thought the 18 had the best balance of power everywhere for the way my bike was setup and where I was riding.

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On one of my 650r's I had setup for dirt when I was running the stock exhaust with the HRC tip and airbox cutout in addition to a stage 1 HotCam, I was running the 18 needle at 12 clicks out from what I recall. My pump setting on this bike with the older style carb was very close to 1.5 turns out. I bought my needles directly from Barnums sales@barnumspro.com (760) 868-8097.

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Mine came with a 19 in the carbuetor and a 17 & 21 as extra. Barnum runs a 17 in his 680cc engine. I was thinking of ordering a 18 for when I get around to playing with it. Mine runs great in the higher RPM's but, is lean down low when I am not into the pump. I was thinking of using an 18 and making it richer down low (modifying the needle).

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