THE EXUP Valve : Pictures

Natural state - open

spring that holds valve open

forcing valve to close


See inside - it's open

The great mystery unraveled!

Picture's worth a 1000 words.

So if one were to dyno the bike with the cables connected then another run with the cables disconnected, we would see EXUP active vs EXUP fully open?

Be nice to have something solid to say the EXUP is there for emissions and not performance other than speculation.

Gany wrote:

So if one were to dyno the bike with the cables connected then another run with the cables disconnected, we would see EXUP active vs EXUP fully open?

Be nice to have something solid to say the EXUP is there for emissions and not performance other than speculation.

See this video for confirmation this is for performance.

skrew wrote:

Gany wrote:

So if one were to dyno the bike with the cables connected then another run with the cables disconnected, we would see EXUP active vs EXUP fully open?

Be nice to have something solid to say the EXUP is there for emissions and not performance other than speculation.

See this video for confirmation this is for performance.

Awesome. Simply great. Thanks a ton.

From what I've seen it looks like the valve moves only at a very select and very narrow window of the rev range.

If starting from a dead stop it'll move slightly under slower acceleration, but if hammering the gears and ripping up through the rev range the valve will move for a micro-second then do nothing.

Great confirmation that the EXUP is not going to be a performance booster through probably about 95% of the rev range. Only in that one little window does it even move.

Great stuff. Great video.

Pretty much confirms mtb's video from a few years ago.

click here

motokid wrote:

Great confirmation that the EXUP is not going to be a performance booster through probably about 95% of the rev range. Only in that one little window does it even move.

Great stuff. Great video.

Just wait, I got an Oregon Scientific camcoder to film my own EXUP movement :)
As for percentage of affected range - IMHO it wider than 5%, mostly because we can't see actual revs, even determine it by sound. Just look at the LeoVince's slip-on performance graph:

motokid wrote:

Pretty much confirms mtb's video from a few years ago.

click here

Thanx, I've seen that video a long time ago :), just forgot it was on Vimeo...