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Revving on.
Posted: Sun Sep 07, 2014 7:49 pm
by 10 inch Terror
Hi all, after changing over exhausts recently I've noticed that when i change gear the engine seems to be revving on. Is this down to an air leak on one of the exhaust joints? Any comments or suggestions very welcome. Thanks in advance Pete.
Re: Revving on.
Posted: Sun Sep 07, 2014 8:38 pm
by eden
probably on the gasket face.
Re: Revving on.
Posted: Sun Sep 07, 2014 8:58 pm
by coaster
What did you change from and what did you fit? Just wondering if it's a jetting issue?
Re: Revving on.
Posted: Sun Sep 07, 2014 9:18 pm
by 10 inch Terror
coaster wrote:What did you change from and what did you fit? Just wondering if it's a jetting issue?
I've gone from a Franspeed super tourer to NK race. It's on a RB 250 and wanted more revs out of the pipe. I took it for an MOT Saturday and it kept stalling when the lights were being tested so i turned the tickover screw in a few turns which sorted the stalling out but when i rode it home it started to rev on. I have turned it back a few turns but it still seems to be doing it.
Re: Revving on.
Posted: Sun Sep 07, 2014 10:01 pm
by sydduckett
Sorry to hijack thread but why would the gasket be the first place to look, I only ask as I have the same issue. Takes a tad to long for the revs to die when you come off the throttle.
Re: Revving on.
Posted: Sun Sep 07, 2014 10:06 pm
by Chris in Margate
Because if the gasket doesn't do its job you will have an air leak and as such a weak mixture. "Revving on" is a classic sympton of this.
Re: Revving on.
Posted: Mon Sep 08, 2014 12:22 pm
by jonashford
I had a problem like this recently turned out a reed was stuck open very slightly
Re: Revving on.
Posted: Mon Sep 08, 2014 1:33 pm
by paulnobodyimportant
Just to reinforce the above comments, the revving sensation says that your engine is running weak and probably dangerously so. Considering that the only change is the exhaust, then it does seem like a leaking gasket is letting air in and causing the engine to run lean. I'd get this sorted before you take the scooter out again so as to avoid an expensive top end disaster. Just to get some confirmation, check the color of your plug to see if its grey, which confirms that its running lean.
Good luck
Re: Revving on.
Posted: Mon Sep 08, 2014 1:44 pm
by Jazzy
It's very unusual for any two pipes to require exactly the same carb set up.
Have you rejetted since changing the pipe?
Re: Revving on.
Posted: Mon Sep 08, 2014 3:08 pm
by Donnie
Jazzy wrote:It's very unusual for any two pipes to require exactly the same carb set up.
Have you rejetted since changing the pipe?
Bingo!
Not to say that there's not an issue with the gasket too, but anyone that doesn't at least go through the jetting and ensure it's ok after an exhaust change is simply asking for trouble.