News:

Create A Forum Installed

  3. EXUP
« previous next »
Pages: [1]

Author Topic: EXUP  (Read 1614 times)

0 Members and 16 Guests are viewing this topic.

EXUP
« on: »
Hi all,

I recently fitted DAM mufflers.
Now i notice something i dindnt notice with stock mufflers.
Looks like, when the bike is not moving, i can rev but its nog so loud.
As soon when i start moving, sounds like the valve opens, even at quite low revs already.

Can anybody tell me here when the valve opens? Has it to do with the wheels turning, starting on certain rpms, or both?
Actualy i like it this way, not planning to change anything, just curious what are the conditions to open up the EXUP valve.
Logged

Share on Bluesky Share on Facebook

Re: EXUP
« Reply #1 on: »
Im guessing yours is an RP18 bike...?

  Yamaha developed the original ExUp valve to affect  a variable exhaust back pressure to take advantage of the interaction with valve timing and scavenging/overlap. The benefits are improved intake/exhausting volumes, as I understand it. So called volumetric efficiency. You'll learn that the ceiling to tuning these engines arrives when you just cant get enough charge into the chambers/past the valves....
 By the time the RP18 was released, Yamaha had resorted to using the ExUp valve to control aspects of the engine tune to satisfy EU4.
 ExUp is used to control noise levels so as to get past the regs. They also limit the revs in certain gears, run it lean to pass emissions by using the closed loop and O2 sensor and the timing curve was (probably) tweaked...
   You might think the ExUp is for the purpose of better performance...It is. It just depends who you are performing for I guess..!
    Clear?
    ???
« Last Edit: August 09, 2021, 09:33:39 am by TimR »
Logged
Re: EXUP
« Reply #2 on: »
wasnt it also something about improving torque, you know 'cause the mt has so little of it.
Anyway its easy to wire open and should be.
Logged
Re: EXUP
« Reply #3 on: »
Quote from: TimR on August 09, 2021, 09:26:47 am
Im guessing yours is an RP18 bike...?

  Yamaha developed the original ExUp valve to affect  a variable exhaust back pressure to take advantage of the interaction with valve timing and scavenging/overlap. The benefits are improved intake/exhausting volumes, as I understand it. So called volumetric efficiency. You'll learn that the ceiling to tuning these engines arrives when you just cant get enough charge into the chambers/past the valves....
 By the time the RP18 was released, Yamaha had resorted to using the ExUp valve to control aspects of the engine tune to satisfy EU4.
 ExUp is used to control noise levels so as to get past the regs. They also limit the revs in certain gears, run it lean to pass emissions by using the closed loop and O2 sensor and the timing curve was (probably) tweaked...
   You might think the ExUp is for the purpose of better performance...It is. It just depends who you are performing for I guess..!
    Clear?
    ???

Clear explanation.
Yes my bike is made 2007.
Is it also known when the valve exactly opens? a certain rpm?
Logged
Re: EXUP
« Reply #4 on: »
ExUp was invented way before the MTO1 was even a twinkle in Yamaha's R&D dept...
 Mine's an RP12. A much better bike, obviously....!! ;D
 As a stage 3 bike, it hasnt an ExUp, or O2 sensor (or closed loop protocol) - meaning I long since stopped thinking about it....
 It is known. I would think the best person to ask would be Micha, from the Donnermeister forum. He flashes these ECU's and knows exactly what is , and isnt OEM ..
 Im sure there are other's who also know, but there is,as you have to expect on the internet, some common misconceptions perpetuated online too...
HTH
« Last Edit: August 18, 2021, 02:08:24 pm by TimR »
Logged
Pages: [1]
« previous next »
  3. EXUP