Yamaha R1 Forum: YZF-R1 Forums banner
1 - 20 of 63 Posts

·
Registered
Joined
·
241 Posts
Discussion Starter · #1 ·
Ok, here is my problem; i bought a 1/2 system for my 04. I wanted to get rid of my EXUP because reading on here, it has been said it acts like a header. I did a search, read up, but now i am asking for opinions on if this really works from member who have done it. If so, how did you do it: block off plate, or wire the valve open? Which is better to do? Does an error code come up? Thanks for the input.
 

·
Registered
Joined
·
252 Posts
Wrong

EXUP is bullshit! Pull that turd out and make a stainless plate to cover the hole. Remove all the cables leave the servo so you don't get any errors.It's only there for EPA noise levels, I understand it cuases the dip at 7000rpm.Gut your cat and you have very close to a full system.

Or don't.

:rock
 

·
Registered
Joined
·
14,028 Posts
Re: Wrong

YZMFER said:
EXUP is bullshit! Pull that turd out and make a stainless plate to cover the hole. Remove all the cables leave the servo so you don't get any errors.It's only there for EPA noise levels, I understand it cuases the dip at 7000rpm.Gut your cat and you have very close to a full system.

Or don't.

:rock
Give sounds advices or sh...

:fact
 

·
Damnit... it's an L, not an I
Joined
·
1,598 Posts
Well I have mine removed, and mid-range made a world of difference. Remove it, definatley, but only if you have a power commander and plan on getting a custom map. I just undid like 4 screws, pulled out the middle section, (actually used the existing hole for the wide band commander, and then hooked the external 2 cables back up, although they were not connected. I'll try and get some pics up tomorrow in the sun.

REMOVE IT!!!
 

·
Registered
Joined
·
241 Posts
Discussion Starter · #10 ·
Thanks for all the info. I do not have the cats anymore because i bought the Y pipe when i bought the slips. i couldn't jutify spending the amount they wanted for a Ti Termi header, so that is where my question arouse from. I do also have a PC. Wouldn't the disabled EXUP act just as a free flowing header would? Sorry for "why" question, though it seems like leaving would be a better option. With the custom map, did it get rid of the flat spot in your power curve? Thanks for the input.
 

·
El Assholio Supremo del Mundo
Joined
·
10,626 Posts
if you don't know the theory and practical application of the EXUP, then don't say it is useless.

thats like saying a larger brake rotor is useless because it weighs more.

the EXUP definately serves a very specific purpose, and it has nothing to do with emmissions or noise level.

Go remove the power valve on a modern two stroke and you get the basic idea of what happens, althoug hit is significantly more noticeable on a two stroke versus 4 stroke.

face it, if exhaust header legnth didn't matter, shifter cart guys wouldn't have adjustable ones.....:fact
 

·
Damnit... it's an L, not an I
Joined
·
1,598 Posts
well, do this... You can remove the exup and replace the external cap back onto the header, and go run it (knowing that it's not mapped properly) If you like it, keep it, if not, replace. It's only about a 20 min. ordeal and you can judge for yourself. if you need, you can check www.ronayers.com for a detailed pics of the exup on the fische's.
 

·
El Assholio Supremo del Mundo
Joined
·
10,626 Posts
Swedie said:
I'd love to see someone here do a comparison run. With and without the EXUP on stock headers. And then also with a custom map.
Yamaha has, thats why it's on there for street use........

I have not seen one real recently, but when i was at school at MMI we did several runs on several different EXUP bikes, including my FZR-1000 and a YZF-750.
Both when properly jetted (still carb'd bikes :crash) with the EXUP made more HP AND Torque at the mid range area, than without.
Also both mademore HP and comparable torque at the top end without the EXUP versus with.

Hence my decision to keep it for street riding.

BTW at the time it wa a 2hp gain at 120hp on my bike for peak hp.

however if i remember correctly, and it has been a while, the midrange difference was approx 5hp and 4 ft-lbs of torque. this was approx 5-8K rpm's.

as i have always said, merely remapping the stock bike, with the stock exhaust could have tremendous effect on the power and rideability of the bike, as most every bike sold has a lean carburetion/FI setting from the factory.
 

·
Premium Member
Joined
·
6,230 Posts
Thanks R1Budha.

I kinda just want to rid the problem with the loss of power at 6-7k. It is very irritating when riding the track. You're like waiting for the extra push before the rpms screams towards 14k.

I want to race with stock system because it is the most affordable at the moment. I'll probably drill out the stock exhausts though for better airflow.
 

·
Registered
Joined
·
252 Posts
Exup is fine for a stock street bike. Mine is a track only race bike. I need more high end steam. The bike runs cooler with out all that exhaust blockage. And with the remap It runs stronger everywhere. I'm no mechanic this is what I'm told by people who know. Is it bullshit?:bs I hope not.:dunno





:rock
 

·
El Assholio Supremo del Mundo
Joined
·
10,626 Posts
YZMFER said:
Exup is fine for a stock street bike. Mine is a track only race bike. I need more high end steam. The bike runs cooler with out all that exhaust blockage. And with the remap It runs stronger everywhere. I'm no mechanic this is what I'm told by people who know. Is it bullshit?:bs I hope not.:dunno

:rock
What the EXUP does is basically add backpressure to the exhaust at lower rpm to simulate a longer header legnth.
If you were to sit and do the math on designing a system, you design the legnth of the header to allow for maximum power at a certain RPM. The shorter the header legnth, the higher that RPM number is.
Thus if you want an exhaust system that is moreflexible, you make it work at multiple rpm ranges by introducing the EXUP butterfly valve into the exhaust collector and effectively legnthining the header.

For track use, where you should rarely see RPMs that low, it is better to not use it on a private bike. However if you are not running at the upper end of the RPM range AT ALL TIMES, i seriously doubt that you will notice the difference at high end versus the difference you will notice in low and mid-range.

Therefore keep it for street, and lose it for true race/track only bikes.


BTW, the difference isn't enough that the rider cannot overcome it in reality........
 

·
El Assholio Supremo del Mundo
Joined
·
10,626 Posts
Swedie said:
Thanks R1Budha.

I kinda just want to rid the problem with the loss of power at 6-7k. It is very irritating when riding the track. You're like waiting for the extra push before the rpms screams towards 14k.

I want to race with stock system because it is the most affordable at the moment. I'll probably drill out the stock exhausts though for better airflow.
Id look to a remap to help that, especially with the very different climate that you face.

I'd be willing to bet your bike is very lean at those RPM's and that is the majority of your problem.
 

·
My R1 powertool rulezzz.
Joined
·
237 Posts
In my opinion the exup on the 04 model is only for sound reasons. MartinC is correct, for the older R1 models. But on the 04/05 model the exup works different and isn't used for switching between cylinders any more, like on the Honda Fireblades of 2000. On the 04 it is just for EPA / sound, with butterfly valves.

If it is better for Hp's at low revs, why doesn't a 600cc have an exup? If there is a bike that would need a better low end, than it would be a 600cc bike.

If you skip the exup, it would definitely mean more sound in the midranges, but not more power.
 
1 - 20 of 63 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top