want to have more torque

moin, i bought a powercommander v and a leovince x3. when i installed the exhaust i notice that i have more torque under 5000rpm with the Oem-exhaust (with Pc5-map, no airbox-lid, removed exup- valve). with the leo x3 i have more power over 5000rpm... most times i drive under 6000...

the second problem is, the Leo x3 is since the last 200miles very loud (I have problemes with the neighbourhood and the police). I filled the exhaust new- but its much too loud anytime...

in the next days i get a Fmf- powerbomb free from a friend. i want to install the oem-muffler with the powerbomb: hope to increase the torque under 5000rpm.

what do you think: do a have change the map (pc5), or do have to make a dynorun. i am afraid that the motor runs too lean with the header...?

will it work to increase the torque???

hope you understand what i mean: im from germany (my english is not very well, you see)

The easiest way to add more torque would be to change the gearing. I recently changed my rear gear and the bike has totally changed.

The stock pipe has a servo valve... it produces selective back pressure that somewhat increases low-end torque, but also inhibits top-end performance. Powerbomb header has a bulb that produces the same effect... how much so, really don't know, would be nice to see extended dyno runs with/without it. Have you removed the servo valve from the stock pipe? Removed the catalyic converter? If so, you'll probably get pretty decent performance from the top and bottom end of the engine.

We all want more torque. And more horsepower too.

It's why most of us have spent hundreds, and some more than a thousand on these 250's.

At some point you just have to realize it's a 250. A single cylinder 250 at that.

You want more torque down low, best bet is gearing change. Larger rear sprocket and/or smaller front. New chain might be needed.

Please let us know if you can fit FmF header on stock canister without needing a custom piece.
The diameter of FmF header pipe is larger than the diameter of Yamaha muffler pipe.

Not sure if the piece FmF supplies for the slip-on style muffler can double as a fit for FmF header to Yamaha muffler or not.

Take pictures. Post results.

I got more low-end and mid-range with an FMF Megabomb head pipe and Q4 muffler.
It was immediately noticable.
Amazingly, the top end didn't seem effected, at least not that I could tell, so the bike still revved as it always did.

"the Exup is no 2-stroke- valve: it don´t increase backpressure in at low range (rpm). the Exup- valve closed only at (I thing) 5000-6500, with full throttle, to decrease the noise, only in the first three gears", my Yamaha dealer said...

I dont know Usa: in Germany and most other european countries, its illigal to have a motorbike with more than 80dbA, you really get troubble with the police (they take your vihicle out of service) ... the exup helps to accomplish the noise-emission... but nobody (without the police) cares: most times they cant scale the noise/ they have nothing to scale, so every biker runs his bike as loud as he wants

i changed already the gearing: 12:45- want to change to 13:50, but it won´t fit (chainguide/chainleader?).

i heard that the Fmf powerbombheader fits to the stockmuffler without the gasket. (Fmfpb-header Od: 43,5mm- Stockm.without gasket id: 44mm), maybe i have to grind the header or the muffler-joint...

what is with the Pc-map- do i have to change the map, if i only change the header...

>""the Exup is no 2-stroke- valve: it don´t increase backpressure in at low range (rpm). the Exup- valve closed only at (I thing) 5000-6500, with full throttle, to decrease the noise, only in the first three gears", my Yamaha dealer said..."

Dunno about that. Try here.

http://en.wikipedia.org/wiki/Four-stroke_power_valve_system

https://www.youtube.com/watch?v=UiwiR2dq4xQ

http://www.mybikeforums.com/forums/showthread.php?t=24294

The EXUP valve and what it does is almost like a religious/god debate.

What it does, and what it accomplishes varies according to who you talk to.

My gut feeling is it's a noise and pollution kinda thingy.

It there was power to be gained anywhere within the range of the motor I'd think aftermarket companies would utilize such a system.
Especially if it's already in place from the manufacturer.

When talking pure performance I don't see racing motorcycles with EXUP valves. Any extra advantage to get more power delivery would be useful in that situation.

Just my thoughts...nothing scientific there at all.

if the exup-system were as good, as its discriped so often, Yamaha would put it in to a wr250f/450f or yz250f/450f. but these bikes are not classif. in a (noise-)emission-class- so yamaha sells this bikes with no exup...

if Yam would say, that the exup is only to reduce the noise-level, everybody would remove it (with Airboxflapper and with no PC-result: these bikes runs too lean). Because big Y. said its makes more torque and ,... venturi.... more hp- poeple thing its good and runs there bike with this fu.. valve

>"When talking pure performance I don't see racing motorcycles with EXUP valves. Any extra advantage to get more power delivery would be useful in that situation. "

You're not running a race bike at low rpm anyway.

I think basically 'bottom end' performance robs 'top end'. Honda and other mfgs have similar valves in their street bikes, (including pretty high output bikes) but not on race bikes. If you really want top end performance, you take the exup valve off.

Effect on WR250? IMHO: the stock muffler has so much 'stuff' in it that it kills top end performance. As a result, many people take the stock muffler off, and adding an exup valve on aftermarket pipes is probably too expensive an option.. Instead aftermarket stuff adds a 'powerbomb' header (& etc) is supposed to get the low end backpressure effect back without an exup. So if you want 'peak' performance you add a muffler and aftermarket header.

Might be nice if Yamaha had made the exup a 'seperate' installation, could see what effect it has with aftermarket pipes then.

Here's a 174 RWHP R1 Exup Valve. It produces back pressure at low throttle in the lower gears. Lots of other 'exup' stuff on youtube.
https://www.youtube.com/watch?v=w5AeHE3IW8I&feature=related

I beleave that an Exup could be a good thing. But in our wr250r it don't close at the low end of the range- it closed at the mid range, only to reduce noise. When i was at a dynojet (thing- don't know rhe word: to scale the hp and make a map), i have had more torque without the exup and the airbox flapper. The flapper slosed in the same time as the exup and only at the first three gears.

But that was not the point: the only thing a want to know is: "runs tje bike too lean, if i only cjange the header?????"

If the powerbomb don't give torque it isn't a problem: i dont have to pay for it, it costs only the time to install...

How many torque do i need to fix the bolts (header)? Is there a list for all bolts? Just get the header- it is 43,5 mm od- fits!! Have you need silicone between header and engine?

germanwr250r wrote:

How many torque do i need to fix the bolts (header)? Is there a list for all bolts? Just get the header- it is 43,5 mm od- fits!! Have you need silicone between header and engine?

If you buy a new header sometimes they deliver a new gasket with it.
Or you can just use the original gasket. No silicone between cylinder and header.
But I used some gasketsilicone between headerpipe and silencer when I installed it.

germanwr250r wrote:

I beleave that an Exup could be a good thing. But in our wr250r it don't close at the low end of the range- it closed at the mid range, only to reduce noise. When i was at a dynojet (thing- don't know rhe word: to scale the hp and make a map), i have had more torque without the exup and the airbox flapper. The flapper slosed in the same time as the exup and only at the first three gears.

But that was not the point: the only thing a want to know is: "runs tje bike too lean, if i only cjange the header?????"

If the powerbomb don't give torque it isn't a problem: i dont have to pay for it, it costs only the time to install...

Im running my wr stock at the moment, appart from 13-48 gearing (This is the bigest increase in performance gain per £ for the wr)

I will allways sort out the suspension before touching the motor, But while we are talking about EX UP i tried this.

Removed the cables from the EX UP valve and tied the valve up in the open position and went for a ride,

The result was a definate lose of torque at the bottom end/ light throttle, and the top end was normal,

This was just what i found, so the ex up must be good for somthing, anyway its only a 250 and a mighty fine one,

cheers V-tec

You need to remove the airboxflapper too. And yoj need a prgramer pc5, fmf.. I noticed more torque without exup. The powerbomb is installed now- fits perfect... But don't work as i hoped.. Think it increase the torque a little bit (maybe, because i only want it) but the bike runs more linear up in higher rpm. Act: pc5-map: stock exhaust, airboxlid removed.

The header gets really hot (glows at night)- want to see after i removed the AIS.