Idle Hangs at 3k

10419 Views 14 Replies 4 Participants Last post by flurbadurba, Mar 15, 2012

flurbadurba

Discussion Starter · Jan 20, 2012

My idle will return to normal (1300) if i blip throttle up to about 2k. But if I rev any higher than 3k the idle will hang at 3k and not come back down. I've been revving it and adjusting idle screw but it hasn't been working. The idle will always hang at 3k. I've already adjusted throttle cables too so there's enough play. I need some advice on what to check/adjust. Thanks in advance. I found similar problems with throttle and tried them out. But nothing quite like this.

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jkv45

· #2 · Jan 20, 2012

Are you sure the cable is free, and letting the throttle return completely? With the engine off, you could open the throttle to different positions and watch that the throttles are hitting the stops at the carbs when you release it.

Or you might have a vacuum leak. If the idle mixture screw don't do anything, the carbs may have deposits inside.

If you're not already, try using Ethanol-free gas - it might help by richening the mixture slightly (over E10) if it's lean. I'd also add 1 oz per gal of a fuel system cleaner like Techron Concentrate or Seafoam to the fresh Ethanol-free gas.

Jay

spooph

· #3 · Jan 24, 2012

any other changes to the carbs? Re-jet? Intake mod? Exhaust mod? what about your air/fuel mixture screws? Touched those yet?

flurbadurba

Discussion Starter · #4 · Jan 25, 2012

Thanks for all the help!

The cable is free. The throttles are hitting the stops when released. I think it might be a vacuum leak. I've looked at some videos on Youtube showing how to diagnose and repair that. I ran some Seafoam through it last month. Where do you get Ethanol-free gas? And how often should I run Seafoam/Techron?

The airbox is removed. I've changed the needles, jets, and pilot screws. It was running alright until i changed the jets to a larger size. I was thinking the carbs aren't seated well and I messed up when I put them back on. I'm holding the pod filter up w/ cable ties to stabilize it and the carbs.

I tried getting the carbies seated more securely and I was careful not to overtighten the ties so I don't pull the carbs up. So far the idle is returning to normal at 1300 rpm but it seems like it's a slow return. The rpm will drop as soon as I roll off the throttle but it seems like it's dropping to idle slower than it should be.

Again, thanks for all the help! It's my first bike and I'm learning a lot just by going through the forums. I picked up a book on motorcycle maintenance and Twist of the Wrist.

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jkv45

· #5 · Jan 25, 2012

It sounds like you still have a vacuum leak.

Check for a leak by spraying water from a spray bottle at areas that may be leaking, and listen for a change in idle speed. You can use other aerosol sprays as well, but water is the safest around a hot engine.

I'd put the airbox back on, if it was mine...

Jay

Blue Ghost

· #6 · Jan 26, 2012

flurbadurba said:
... Where do you get Ethanol-free gas?

...So far the idle is returning to normal at 1300 rpm but it seems like it's a slow return. The rpm will drop as soon as I roll off the throttle but it seems like it's dropping to idle slower than it should be.

There are a couple of web sites that list 100% gas stations. These lists are updated by users so they may or may not be accurate, as some gas stations often change their fuel distributors.

Ethanol-free gas stations in the U.S. and Canada
Find ethanol free gas near you!
Ethanol-Free Gas Stations

As far as your idle returning slowly, have you considered drilling the slides? This seems to help out with the throttle response for those who have re-jetted and gone to open pods, although it's not recommended by some.

spooph

· #7 · Jan 27, 2012

I think this is a jetting issue.... flurbadurba, please post up your jet specs... idle, main, air/fuel mixture screw, and needles position please.

flurbadurba

Discussion Starter · #8 · Jan 27, 2012

The video I saw on youtube suggested using starting fluid. Spraying water does seem safer on a hot engine. I'll be trying this again.

I think idle mix screws were turned out 2 3/4. Needles are at 4th groove. Jets are 115s from Jets R Us.

jkv45

· #9 · Jan 27, 2012

flurbadurba said:
The video I saw on youtube suggested using starting fluid. Spraying water does seem safer on a hot engine. I'll be trying this again.

I think idle mix screws were turned out 2 3/4. Needles are at 4th groove. Jets are 115s from Jets R Us.

I just saw some info recently that said jets with the same number made by different manufacturers (to fit the same carb) can flow differently.

I don't think this is an issue in your case, just something to consider when altering jetting.

Jay

spooph

· #10 · Jan 27, 2012

Ah ha! Thanks for the info! You might want to check this place out:
FAQ Mikuni vs keihin vs dynojet

I'm assuming your on the stock Keihin carbs, which means you have proper Keihin jets from Jets R Us...

Being that my reference is with DynoJets, and not Keihin's, I looked at the conversion chart, and your 115's = 110 in Dynojets.

I know at one point Racer X was running 110 Dynojets, and even with his heavily modified bike it was over kill... I think you're mains are WAY too big, and your flooding.

1.) Try slamming your needle down as low as it can go - put the clip on the very end of the needle, as far away from the tip as is possible, and see what happens... If this allows the bike to rev higher, start decreasing jet sizes....

flurbadurba

Discussion Starter · #11 · Feb 9, 2012

i changed the jets to 110 and fixed a vacuum leak and now things are running fine! thanks again.

spooph

· #12 · Feb 9, 2012

Glad to hear! Now a video of a properly running bike would a fantastic "thank-you"....

flurbadurba

Discussion Starter · #13 · Mar 15, 2012

Ninja 250 rev - YouTube

spooph

· #14 · Mar 15, 2012

Yea! Woota-toot! That's great! Now don't disappear on us...

How's it riding?

flurbadurba

Discussion Starter · #15 · Mar 15, 2012

haha sorry. it's been riding great! thanks again spooph.

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