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mznyc

Revs shooting through the roof!!!

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Haven't been on the form for a while,busy with life,but getting the Scura prepped for the season and  on a shake down test ride coming in to a turn,shut throttle off and the revs stayed at 5K,pulling in the clutch only has has the revs shoot to red line! Shut her down,looked for an obvious air leak roadside and found nothing.Re-started and rode home fine.I've had similar symptoms years ago and found a TB boot loose,don't remember the revs going up when pulling in the clutch.But all looked OK roadside.

I'll check,

Throttle assembly for sticking

Air leaks anywhere

Anything else from symptoms?....

 

 

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Possibly a broken return spring on the throttle body? A friend has that problem as we speak. He can't find one anywhere, so I'm going to make him one. Hopefully.

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Thanks Chuck,I'll take a look,I'm leaning to an A/F-TPS-ECU  issue as when I pulled the clutch in it immediately shot up in revs where I had to shut down so as not to blow the motor,it did happen right after I gave it the juice making a quick pass on a back road so I'm not dismissing a mechanical linkage possibility....

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The throttle linkage does have a tight spot on the left where the white adjuster knob can hang on the shock reservoir adjuster.

Also, this "tunnel" for the lingage rod should not have anything else (wiring, hoses, mouse nest, etc) sharing the space . . .

IMG_2757.jpg

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Either a physical issue preventing the throttle from closing 100% (even open a small amount will cause really high revs without a load) or an air leak. For it to come and go like that my money is on something keeping the throttle from closing 100%. If it happens again, reach down and manually try to close the throttle at the throttlebody.

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WOW This exact issue happened to me 2 weeks ago and spooked me pretty good. I had to Kill it on the highway but to a few seconds to "calmly" figure out what was causing it to go full throttle. (exact position it was when I decided to one itup) And yes the white twisty thing was caught on the rear shock precharge. 

 

I intended to post it on here and im sorry I didnt. Glad all is ok. 

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Thanks for posting that, ColdandWet! Y’all notice the lock nut on my white balance knob, above. That and sliding the shock reservoir rearward are good method!

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Those things are entirely too close IMHO. Luigi must have been promoted to design.. :rasta:

At any rate, they need to be carefully located.

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The only thing that would deter me from suspecting the linkage as a sure fire cause is the fact as soon as I engage clutch rev go to redline,release it and back to 5K which steers me to A/F issue by a confused ECU getting bad data or a combination of mechanical-bad digital messages...

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The other main option is an air leak. An air leak can cause that, it revs up with the reduction in load caused by pulling in the clutch, Any load, like having to spin the gearbox, and it doesn't rev nearly as high. But it is odd to have an intermittent air leak. Not impossible, just not common.

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Looking at the wiring diagram, pretty sure the ECU doesn't get any data from the clutch switch, so pulling in the clutch shouldn't affect the ECU's behavior as a result of that action. It has no way of knowing you're doing it. I'd wager it's as GuzziMoto says, removing the load is allowing the engine to rev up. Did you get a chance to see if the throttle body linkage is catching or has the potential to catch on anything?  

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On 6/7/2019 at 8:44 AM, GuzziMoto said:

The other main option is an air leak. An air leak can cause that, it revs up with the reduction in load caused by pulling in the clutch, Any load, like having to spin the gearbox, and it doesn't rev nearly as high. But it is odd to have an intermittent air leak. Not impossible, just not common.

That's what I said I checked and suspected in the first post Gooz....But the load concept is interesting,...When I can get back to it,I'll post what I found,or not,....

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