Cheapest DIY Servo Bypass

Go back and check the TT thread. rydnseek went to Radio Shack.

Sarah

Guys and Gals, I am new to the WRR seen. What exactly is the EXup. What does it do and why should i remove it?

colorado.warhorse wrote:

Guys and Gals, I am new to the WRR seen. What exactly is the EXup. What does it do and why should i remove it?

click this yellow text

Short story : it regulates back pressure in the exhaust pipe which, depending on who you talk to, they will tell you that power increases at certain areas of the power curve with the EXUP working.


Others will question why after-market exhaust manufacturers won't include such a thing if it actually works that way.

It's a bit like religion....a lot depends on who you talk to.

Like most things, if the answer is a little more involved than people have time to absorb then they just don't bother.

I like this explanation. It's not simple but it covers, specifically, what Yamaha are trying to do with their EXUP system.

http://www.r1-forum.com/forums/archive/index.php/t-262749.html

^^I can't believe I read all that. Long is right.

colorado.warhorse wrote:

Guys and Gals, I am new to the WRR seen. What exactly is the EXup. What does it do and why should i remove it?

Yeah i didnt get a complete understanding out of it ether(at first)...but there is so many diff opions. But i went am got rid of it and made my own homemade servo with some resistors and some diodes...and seems to work great.

Radio Shack = 1/4 watt 10K resistor.
Plug it in to the black/red and red/black wire ports.

WORKS great.

I have some extra resistors. PM me if you need one.

The 1/4Watt 10K resistor works great.
PM for one if you need it.

Ok I took mine apart to see what the hell this servo really is and it's just a motor with a 7k pot. The gear turns the pot.
This is why we see the 2 3.3k and 7.5k Could me a 7k Resistors and the 1 Diode make up the pot and the 10k 20k is in place of the motor?

I'm going to pull the pot out and use the OEM plug and pot and just plug it back in..
Hell this mod is a free one. So was the leanover switch just open it up and gooob it up and put it back to dry and then zip it out of the way and your good to go...

edteamslr wrote:

Like most things, if the answer is a little more involved than people have time to absorb then they just don't bother.

I like this explanation. It's not simple but it covers, specifically, what Yamaha are trying to do with their EXUP system.

[url=http://www.r1-forum.com/forums/archive/index.php/t-262749.html

http://www.r1-forum.com/forums/archive/index.php/t-262749.html[/quote[/url]]

Makes me hesitant to mess with it... or the flapper thing. There's a remote chance that the Yammie Mommie Engineers are right...?

Keeping it and getting the power out of it would be way too much work.. I just need a bit more power to help get the front wheel over them big ass logs and rocks I need to get over in the racing I'm doing...
When they become the hot ticket on all the race bikes I'll put one back on the bike..

you guys rock for sussing this out, just picked up my wr250r :) let the mods begin,

bought this to replace my DR650 ( with FCR carb and gsxr exhaust, ims tank etc etc ) + KDX200 combo

thought id get rid of bikes and go back to having just one again, pretty hard to beat the WR for that !


HI

The EXUP valve report on R1 forum . . .

I stopped reading after I read this.

"Honda's VTEC switches between two and four valves per cylinder based on revs, but isn't really variable as valve lift and duration is unchanged."

As a Honda tech for over 9 years and building a few high compression camed out motors I know that statement is completely false.

Makes me very curious about all the other info.

wildbillhatchbac wrote:

The EXUP valve report on R1 forum . . .

I stopped reading after I read this.

"Honda's VTEC switches between two and four valves per cylinder based on revs, but isn't really variable as valve lift and duration is unchanged."

As a Honda tech for over 9 years and building a few high compression camed out motors I know that statement is completely false.

Makes me very curious about all the other info.

I hadn't read it, but once you pointed it out I decided to. I LOL'd Extra valves huh?!?!?! Next I'll believe that stickers give you HP.

You mean you can't believe everything you read on the internet?!?

EXUP. Some hypothesize that Yamaha has used it to help limit noise. I first heard these rumblings referencing first gen R1's. Having one of these with a slip-on I think there might be some merit to this. Mine is not loud despite the "FOR RACE USE ONLY" label on the exhaust. Is this because I retained the EXUP . The motor has a relatively long stroke, so why would it need the EXUP from a performance stand point. I don't expect Yamaha to divulge.

Now considering our WR's. It seems Yamaha has thrown the kitchen sink to keep this thing quiet (It is a high revving 250). After changing the exhaust, I did not experience any loss of grunt (not that there is much there anyway). I did notice the bike is louder at low RPM's but not so much at high RPM's (relative to the stock exhaust). Is this the Q4 doing it's job or due to the absence of the EXUP? Anyone here running the stock exhaust where the only mod is removal of the EXUP? Unless some one does this, all we can do is guess. I removed mine because the only thing it seemed to bring to the party was more weight.

I feel I should state that I am not an engineer or mechanic & have know idea what I am talking about. That's why I am putting it on the internet.

I just bought a used 2008 and about to install a FMF slip on. I just wanted to confirm that I can remove the EXUP valve and cables but leave the servo and won't get a CEL. Or is it necessary to install a servo sub? Thanks.

You can remove the Exup, as long the servo or servo seb is in place. Most people like to remove the servo for the weight.

abchel wrote:

You can remove the Exup, as long the servo or servo seb is in place. Most people like to remove the servo for the weight.

thanks, what's the servo "seb"?

I think he meant "sub"; same as servo bypass.

Sarah

So i just went to "The Source"(in Canada) and they only carried 1/4w resistors but they weren't 7.5k. Does this number matter if its higher?
Jonny-NITRO said on the last page that he bought 1/4w 10k resistors and it worked for him, should it work for me?
Thanks
Matt.

Oh Canada so I've searched far and wide an went to every electronic store and ended up feeling like a huge geek walking into a robot repair shop to find a resistor.
Still though the wrong one. I found a 1w 7.5k one, should that work? Anyone?
So if ur from, well, anywhere but Canada and complain because u can't find stuff for ur bike, come live here and try to find parts. Oh and then add about 50% too the price. Lol

mattnadz wrote:

Oh Canada so I've searched far and wide an went to every electronic store and ended up feeling like a huge geek walking into a robot repair shop to find a resistor.
Still though the wrong one. I found a 1w 7.5k one, should that work? Anyone?
So if ur from, well, anywhere but Canada and complain because u can't find stuff for ur bike, come live here and try to find parts. Oh and then add about 50% too the price. Lol

I'm pretty sure SheWolf in backwoods Vernon found the parts to make hers up.

I'm also fairly certain that Krabill and a few others make these up at a very friendly price.

Lol no, its not that bad out here and the resistor wasn't expensive. It was like $3.50 but just parts in general are a pain to find. Unless I want to pay a lot for shipping and duty.

But anyways does anyone think a 1w 7.5k resistor work for the servo bypass?

i built one just like what was on the wrrdualsport site. is there a difference in just adding one resistor or did i waste my time building this, only 6 bucks either way but i guess the resistor would be a touch lighter than my little circuit board.

Yes, that resistor will work. I went to an electronics shop that fixes stuff and they gave me 2 of them, so I have a spare. So far, nothing has coded, and it's been in there for a long time now.