technical question exup

colin1 · Captain Safety Joined: 17 Feb 2005 Karma :

I've heard of exup valves, and have the vague idea its a bit like the power valve on a 2 stroke. ie fully open at high rpm, and partially closed at lower rpm to improve low rev torque by some dark art of back pressure or something.

I'm not wanting an explanation of a 2 stroke power valve here, but I do want an explanation on exups.

I found this https://en.wikipedia.org/wiki/Exhaust_ultimate_power_valve

I guess what I want to know is, do all sports 600s and 1000s have something like this where the 4 header piped meet the pipe to the exhaust, or just some ?

This is partly influenced by the fact I've got a full system I got cheap off ebay, that I may one day fit to my triumph TT600.

I've removed the standard exhaust before and didn't see any sign of wires to a servo of an exup.

I'm particularly interested in peoples views on this comment "Mostly I think it helps pass EPA tests since open pipes tend to pass unburned gas. With the EXUP the valves can then be put on a steeper cam and still hold the exhaust gas under control. "

If thats the case, I wouldnt lose any low end performance if my 600 did turn out to have an exup, as it would just be there to fiddle emmmissions.

Having said that, as far as I know the tt600 doesnt have an exup type valve, but if anyone knows different, say so.

Apparently the 675 has one, but i havent verified that.
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P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

im sure the FZR600 and FZR1000 had an exup model for the USA. All i know is they are the less powerful versions of the FZR as it restricts them in some way...
Feel free to correct me if im wrong..

robbieguy2003 · World Chat Champion Joined: 30 Mar 2007 Karma :

The 600rr has one of these valves, the little motor in mine actually failed leaving it wide open.

It got replaced under warranty, however after phoning Honda they said it was there for emissions/some performance at low revs - so the back pressure trick.

They said it was fine to ride until I could get it into the shop. It took me nearly a week to get in with it.

Had no noticable performance problems but did get a lot more smoke out of the exhaust from a cold start, it would also continue to smoke for upto a few minutes after shutdown.

Obviously a different bike but the aboves my experience with the things on an IL4 based bike.
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MarJay · But it's British! Joined: 15 Sep 2003 Karma :

The TT600 doesn't have an exhaust valve. Exup is a Yamaha trademark, and Honda have a similar thing on the 2000 onwards FireBlades called HVIX.

The Daytona 675 has a flap in the airbox that closes at around 5000rpm because this is where the type approval noise tests are done... but as far as I am aware it has no exhaust valve either.
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chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

AngelGrinder · World Chat Champion Joined: 09 Jun 2007 Karma :

The 675 definately has one. Had to free the bastard thing, as it had seized over winter!!
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salty21 · World Chat Champion Joined: 08 Jun 2006 Karma :

robbieguy2003 · World Chat Champion Joined: 30 Mar 2007 Karma :

woodyfjr · Scooby Slapper Joined: 25 Jan 2006 Karma :

The EXUP valve on early 1000 FZRs were for more torque at lower rpm then opened up to allow more power as the cam timing was a bit wilder.

Racers took them off as they were always over the rpm range so the valve would have been open anyway.
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colin1 · Captain Safety Joined: 17 Feb 2005 Karma :

Noxious89123 · World Chat Champion Joined: 10 Jun 2007 Karma :

colin1 · Captain Safety Joined: 17 Feb 2005 Karma :

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Not sure if anyone makes an aftermarket system with an Exup style valve in it.

EXUP valve is there to allow sillier cam timing / manifold design, optimised for peak power. On a normal system this would land up with a dire mid range (and that is certainly what you get on an FZR1000 EXUP if you fit an aftermarket system without the valve), as the pressure waves that work at high rpm to draw mixture from the head does the opposite and rams the burnt gases back into the head. The EXUP valve screws up the pressure waves to prevent this problem.

All the best

Keith
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woodyfjr · Scooby Slapper Joined: 25 Jan 2006 Karma :

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

colin1 · Captain Safety Joined: 17 Feb 2005 Karma :

When I bought mine it had been partially set up with the tuneboy. The guy had got the dyno place to do the settings, starting with the high revs. Unfortunately, as he was paying by the hour, and it was taking a while, he stopped the guy from doing the full range. Did most of it, but not completely the lower revs like 3k 2k.

Having said that, it was smoother at 4k. In the normal fuel map, there is a flat spot at 4k, to get the bike through emmissions tests that are about 55mph in top gear.

It also seemed smoother throughout the range. When cold with a standard tune, throttle can be a bit twitchy.

Unfortunately, when I took the bike to a shit triumph dealer, with an unrelated problem, he decided to repalce it with standard fuel map, and cap off my scott oiler. He was trying to eliminate possible cause of the problem I was having.

I do have a copy of the custom fuel map somewhere, but never got round to putting it back on the bike, or setting up the scott oiler again.

Id say the improvement with a standard can, is slight but noticeable, whether its worth buying tuneboy lead and software, is whether you have money to burn or not.

It would definitely be worth doing with a race can or full system though. Not sure I'd bother with standard can.

My tuneboy lead came with the bike.

I would recommend downgearing though. My bike came downgeared, but since then I'm too tight, so only fit standard sprockets as they are cheaper.

Nice to know that Quill are a good brand, I don't know much about exhausts really Smile

and nice tip about refitting the exhaust bit on the inside before re-rivetting. I hadnt thought of that.
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chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

How much is Dyno time/ how long would it set up?
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colin1 · Captain Safety Joined: 17 Feb 2005 Karma :

I dont know, someone else might.
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woodyfjr · Scooby Slapper Joined: 25 Jan 2006 Karma :

It can cost quite a bit. The more experienced the dyno man the quicker generally.
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