You will love this video!


Then go here to look at the results of the Exup dyno testing.
vmaxguru.com/Tech/Gen2/Gen2_Polyanna/Polyanna_Page.htm

if you remove theexup, you will have the same power at high but much less in low, the engineers would do (without EXUP) valves open later with the subsequent loss of performance in high..the fastest sport motorcycles in the world are including the EXUP now, is a very expensive piece so it does not add benefits..noise problems could solve it by a fraction of the cost of an EXUP..Japanese do not throw the money or make more expensive the bike for nothing, the day someone makes good aftermarket exhaust with EXUP 4 in 1, all will say that is the "big solution"

cggimenez wrote:
OK.....you win.

I hear you Mark.. I spent countlesss hours at Tims, and as many as 19-20 dyno pulls a day on my bike, testing air filters, ex-up, maxtuner, airbox mod, etc. and we learned a lot. I guess some people don't need to learn. They've got it all figured out without any time on a dyno, seeing the actual results before & after each mod. The Vmax V4 doesn't benefit much from an exup valve, not near as much as the inline 4 cylinders, but it is beneficial in noise reduction. Tim & I unhooked ours early on and noticed 6 to 7 ft lbs of improved torque (certain rpm ranges). It stayed disconnected until I got my xpipe, which we both know is a hell of a lot better than a couple of bypass tubes welded into the cat.. The big V4 wants to BREATHE.. Hoping to hear more from you on your new exhaust vs the original xpipe.

CG have you considered the possibility that your " cat bypass tube" has changed the resonance of the exhaust? That alone could render the exup valve useless or even detrimental.

cggimenez wrote:
No EXUP. So are you saying that the EXUP valve adds 7HP at the bog?

The EXUP on this bike does not function like an extra power exhaust valve, but it could theoretically be used for that purpose. On this bike, the EXUP functions to divert the exhaust gas thru a second catalytic core so the bike can pass emission standards. In 4th and 5th gear, the stock and race ECU has the EXUP programmed to fully open. In normal situations, the EXUP function is typically not even dyno'ed as most dyno pulls are performed in 4th or 5th gear.

Tim, I thought I remembered you saying somewhere that the AFR was on rich side with the EXUP closed. That is why I assumed it only helped with decibel levels.

It is, but my guess is there would really be no reason to install what looks like a second palladium core in the exhaust system for the purpose of noise control.

VMaxGuru wrote:
Good point.

What I'm starting to believe more and more is what a Yamaha insider once told me. He said that the Gen2 was released early....actually rushed to market after a lot of it's details were leaked and appeared in an on-line article (I forget who's article it was but I have it in my office somewhere). If you remember there was virtually no information being released at all, everything was speculation.

This would explain some of the the "why did they do that?" questions on some minor issues on the bike. The kind of details that would have been being worked on near the end of the final design/testing.

Sounds a bit absurd I know after waiting so many years for the new VMax.....that it would be rushed at the last minute.