Butterfly exhaust valve


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Aug 21, 2021
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I am doing a bit of maintenance on my 2014 GS and noticed that the exhaust valve is not functioning properly at start up, getting access to the valve, I am able to assist with the startup test by gently helping the valve to close. As it is stuck open, would this be a MOT failure? i.e how important it the valve for a hot bike at an MOT?
They fail regularly.. from 1,000 to much more. Mine went at 36,000 just out of warranty of course. I did manage to release it once, it made no difference just failed again. The ONLY difference is it barks a bit when you open the throttle to overtake. That seems to be an improvement to me. Fuel consumption is unchanged. It's not an MOT item. Replacement means replacing the whole 2 header pipes, cost about £1,800. Another good reason to leave well alone.
You can get it to move by lubing it, but it will fail again. Just ignore it, if it is stuck open no issues at all. There will be a fault on the ecu if you plug it into the mothership or a GS911. So if trading in, they may use as a bargaining tactic.

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