Need help diagnosing an issue - Flapper stuck open?

0612Devil · Apr 27, 2016

Gents,

I've been having symptoms on my bike for about 2 weeks of being extremely down on power, cylinders cutting in and out, low noise, rough idle etc...

Thought it was bad gas, but drained the tank and replaced with fresh fuel to no avail.

After some googling, I thought the symptoms might be the result of the exhaust flapper being stuck in the closed position.

Below is a picture from a fellow member of the valve in full open position(with an exhaust that isn't rusted to .... btw...)

Now here is mine(which IS rusted to hell and back due to 16k hard miles).

Correct me if I'm wrong, but mine looks like it's in the closed position correct?

Thanks!

tslsx74 · Apr 27, 2016

Looking at the image, it does appear to be in the closed position.
The default for the flap in case of system failure is to return to the open position as the flap is spring loaded.
When the bike is started, the servo motor pulls the flap shut and reopens as needed based on engine rpm and load.
When you first turn the key on, you should hear the servo motor activating as it does a system check every time the ignition is turned on.
If your bike does the servo check when turned on, then the servo is fine and the flap is mechanically seized. If you do not hear the servo, then you have an electrical failure. Start checking fuses, relays and wiring.
If servo works, try soaking the flap bearings and bits with PB blaster, WD40 or any other penetrating oil.

Hope this helps.

timwu12 · Apr 27, 2016

take a spanner or adjustable wrench or use a ratchet and socket or hit it with a mallet on the nut and force it to move back and forth.

If it is rusted shut, that'll break it loose again so that it's not stuck closed. Afterwards, do as telsx74 said and hit it with penetrating oil or WD40

Phl · Apr 27, 2016

Beat the .... out of it to move it in its original position, then remove the y-pipe and delete the flapper valve. Pm me if you need help

0612Devil · Apr 28, 2016

tslsx74 said:
Looking at the image, it does appear to be in the closed position.
The default for the flap in case of system failure is to return to the open position as the flap is spring loaded.
When the bike is started, the servo motor pulls the flap shut and reopens as needed based on engine rpm and load.
When you first turn the key on, you should hear the servo motor activating as it does a system check every time the ignition is turned on.
If your bike does the servo check when turned on, then the servo is fine and the flap is mechanically seized. If you do not hear the servo, then you have an electrical failure. Start checking fuses, relays and wiring.
If servo works, try soaking the flap bearings and bits with PB blaster, WD40 or any other penetrating oil.

Hope this helps.

Yep, looks like it's mechanically seized. I can hear the servo check but the mechanism only moves slightly.

Will hit it with some WD40/wack it with a mallet and let ya'll know.

Thanks!

maslov · Apr 28, 2016

Perfect excuse to upgrade the exhaust!

jyli19 · Apr 28, 2016

^ what he said.

Phl · Apr 28, 2016

this is what i found in a 1299 y-pipe

hint: unwelded welding wire)

Imagine that breaking and getting stuck

Need help diagnosing an issue - Flapper stuck open?

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