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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: 90K75RTGerne on August 23, 2023, 11:49:24 AM

Title: Random high revs
Post by: 90K75RTGerne on August 23, 2023, 11:49:24 AM

1990 K75RT, fairing removed.
While riding, the engine will suddenly rev up to 6 or 7000.  If I don't roll off the throttle it will of course accelerate wildly. Rolling off the throttle fixes the problem immediately.
I've tried:
replace all vacuum lines
replace throttle position sensor (TPS)
replaced throttle cable

Have not messed with AFM.

Has anyone run into this and have advice?
thanks

Title: Re: Random high revs
Post by: Laitch on August 23, 2023, 12:32:06 PM

Get some propane or carb cleaner, start the engine then carefully spray around each of the throttle body rubber manifolds descending from the air box—one-at-a-time. Spray the z-tube that runs from the crankcase to the air box also and verify its condition. If there's a change in the revs when sprayed, the component is leaking. These are simple measures to determine common problems. If the air flow meter is plugged in, leave it alone for now.