What is an EXUP valve?

The term ‘EXUP valve’ (Exhaust Ultimate Power Valve) is often used in relation to motorcycles, but what is an EXUP valve and how does it help you ride faster?

The EXUP system was first introduced in motorcycle exhaust systems by Yamaha in 1989 on the FZR1000 and has since been used by Honda (HTEV – Honda Titanium Exhaust Valve and H-VIX – Honda Variable Intake/Exhaust systems), Suzuki (SET – Suzuki Exhaust Tuning) and some Triumph motorcycles.

Yamaha R1 EXUP valve
Yamaha R1 EXUP valve close up
Yamaha R1 EXUP valve back

A Yamaha YZF-R1 EXUP valve (2002, 5PW model)

An EXUP valve is a butterfly valve used in 4 stroke motorcycle exhaust systems that regulates the flow of exhaust gas released from the engine depending on how much power (throttle) is being used.

Note: The valve is electronically operated by a servo and is usually mounted just after the downpipes (aka headers).

EXUP valve open
EXUP valve  closed

Yamaha R1 EXUP valve in the open and closed positions

As the power is increased (by twisting the throttle grip) the butterfly valve opens allowing the exhaust gases to escape. This helps improve performance at lower revs by reducing the diameter of the exhaust (which helps the gas to be forced out of the exhaust system).

Yamaha YZF-R1 EXUP servo
Yamaha YZF-R1 EXUP servo case removed
Yamaha FZR400 servo
Power valve servo

Different power valve (EXUP) servo motors (Yamaha R1 and FZR400)

The EXUP valve is controlled by a (usually) remote electric servo motor controlled be the ECU.

Note: A servo is an electronic switch that controls the position or speed of something.

R1 EXUP valve cables

Cables that go from the EXUP valve servo motor to the EXUP valve to open/close the butterfly valve.

Thanks to: Four-stroke power valve system – Wikipedia

Disclaimers:
The information provided on this page is ‘to the best of our knowledge’ and should not be taken as 100% accurate!!

To keep this page as a free resource for people to use, there are affiliate links (mainly Amazon) throughout the article. These affiliate links help maintain the cost of running this blog (basically, if you visit Amazon through one of the links and buy something, we make a few pence!).


Comments

3 responses to “What is an EXUP valve?”

  1. Simon Haddock Avatar
    Simon Haddock

    Problem with the EXUP valve is that it is almost hidden and many tended to overlook the need for it to be lubricated on a regular basis . They often got stuck , frozen up with corrosion and stopped working …( their close proximity to the road) meant the valve was first in line to get covered in all sorts of muck . water ingress , salt ( UK ) and the cold temps with damp roads, meant all sorts of problems in the long run …

    1. Good points, cables were also prone to seizing (again, due to road muck)

      1. Simon Haddock Avatar
        Simon Haddock

        Great idea in principle (when it worked) and if the design had been better thought out would have worked far more productively if the position of valve and cable were situated away from the obvious problems that indeed it suffered.

        All the Genesis range of machines were quite amazing in their overall design and function …Light years ahead of the other four .
        I bought the previous model the FZR 1000 back in the 1980’s and currently own a 97 YZF 600 Genesis .

        Incredible bikes .

Leave a Reply

Your email address will not be published. Required fields are marked *