Idle hanging up on Edelbrock

Hi all, I have done a search and found a number of posts relevant to my question, but I still can't track the problem dow.

The idle on my Edelbrock carb doesn't return to where I set it, it hangs up at higher rpms most of the time, sometimes it returns to idle fine.

I have checked the intake manifold for leaks and found none. The cables are fine. I took the carb apart and meticulously cleaned it. My valves are adjusted correctly.

This problem suddenly appeared, the carb wasn't hanging up before.

Best I can tell the mechanical part of the carb seems fine, meaning the slide is returning to the idle position. It moves smoothly.

What else should I be looking for?

Thanks, 4Takt

I had the same problem with an Edelbrock on a '98 XR628. The problem didn't show up right away after installing the carb. After a couple of months of usage, the slide started sticking when the throttle was chopped. The stock 600 carb slide will stick when it becomes a little worn because the manifold vacuum is so high when the throttle is off. I assumed that the same thing was happening with the Edelbrock. Anyhow, Edelbrock sent me an improved slide and return spring (stronger) and that cured the problem. I have since had the carb on a stock '91 XR600 and on a 628 engine that I built for flat track, the carb still works great.

Daayuum,

I wish I would have known this - before I bought one, that hasn't got here yet.

Cause my baby is running very sweet right now. I am having fears about having to do battle with a new carb that will be here this weekend. :applause:

Here's another piece of the puzzle:

When the idle hangs up high, I can lower it by putting the bike into gear, stepping on the brake, and slowly releasing the clutch. As the friction slows the rpm it "sucks" the idle down to normal, meaninig the bike will now idle normally when I take it out of gear.

What's that tell me?

4Takt

I had one on my 400ex, did the same thing. I had to blip the throttle and get the slide to slam closed to get it to idle. Mine would even vibrate back open a little and stick. Sounded like I was some idiot reving my engine all the time.

Anyway, get with Edelbrock, they sent me a heavier spring. Made the throttle stiffer (hard on a thumb), and mostly fixed it. I didnt have enough mods to take advantage of the carb, got tired of messing with it, and sold it.

I too had the same problem too. I didn't realize they had such a big problem. I thought it was just mine! It was an easy repair though.

It was an easy repair though.

What was the repair? A stiffer spring?

4Takt

Mine did too , inconsistantly & found it (needle hitting baffle plate in bottom of bowl . I think they have a bigger hole for needle now . my plate used to shift around a bit . Next time it happens.stop engine & then twist throttle and let go . Do you hear it bottom out ? Mine you could hear the difference. Rob Barnum corrected mine . The last time I pulled apart I lost the check ball BB. Hope its your spring though, cause i think that is easier to do.

What was the repair? A stiffer spring?

4Takt

Yes....a slightly stiffer spring did it for me.

an air leak between your carb and engine would cause the symptoms you describe. Check the mounting of the carb between carb and engine. Sometimes that manifold is a little tweaked (twisted or skewed) and lets a very small amount of air in, especially when the engine is hot.

-T

an air leak between your carb and engine would cause the symptoms you describe. Check the mounting of the carb between carb and engine. Sometimes that manifold is a little tweaked (twisted or skewed) and lets a very small amount of air in, especially when the engine is hot.

-T

That was my first suspicion, but I can't find anything wrong with the intake manifold.

Are there any tests I could perform to rule out an air leak?

4Takt

As I recall, you can spray the area that you suspect the air leak (WD-40? or???).

If your idle slows when/where you spray, you've found the leak.

(Never done it myself....my leaks are usually pretty obvious)

-T

PS: Someone else may know a better method.

My bike had the same problem and it turned out the accelerator pump shaft was bent. Edelbrock is warrantying mine after having the carb for 5 years so I think it's a known issue. Anyone with the same issue may want to check it to make sure the action is smooth.

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