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K6 GSXR1000 full Yoshimura system - lose bottom + midrange?


Matt Strange
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Managed to get a nice Yoshi slip-on for £150, good enough imo - I'm not exactly in the same league as Marquez after all :)


I had a bit of a fiddle (basically disconnected and wedged open the valve) and didn't like the response. Maybe a full system and a

map would be different but for the sake of buying a full system and gaing probably 2hp, is it really worth it?. I can see it being a slight

hinderance on tight circuits like Rockingham, where the bike will sit under 5k in 2nd gear, on at least three corners I can think of.


I expect it would probably fail noise regs too on some circuits too.

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I removed the SET valve on my Gixxer600. sounded better with no noticeable reduction in power.


Many believe its only there for noise reduction as it stays closed below 5krpm, and funnily enough, all noise testing for UK type approval happens below 5k...

On the track youre rarely gonna be below 5k, so take it off to save weight. you need to pull the wire from the ECU to extinguish the FI light though, or put tape over it ;)


As for the gearing, from what i've been told, all type approval happens at 70mph, so you'll find the bike is geared to keep the revs below 5k at 70mph thus keeping the SET valve closed to keep the noise down...


I'm a firm believer that all bikes leave the factory with tall gearing designed for low noise, low fuel consumption and low emissions and to make them less wheelie prone.

For the track, none of that is important, so i would start by dropping 1 tooth from the front sprocket and then play with the rear (adding more teeth) depending on the track.

Be aware your speedo reads off the front sprocket so changing the gearing will cause the speedo to over/under read.

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It definitely makes my bike (standard pipe + fuel map) appear that bit flatter between 4-8k rpm with the set valve bypassed in the open position, I expect it can be "mapped out" with a FI controller but how much difference that will make to the rest of the rev range is not so apparent. Somethng that can ony really be confirmed or disproved on a good dyno with an honest operator I suppose.


I expect any gains to be pretty minimal, after all its hard to add proper power to a naturally aspirated bike without serious engine mods, BSB only put out 15-20 more hp with head mods, different cams & an ECU. All of which = lots of money for little gain.


Unless we go down the pub and are talking about the mighty K4 GSXR with 190 rwhp! After only £3000 of mods, half of which were stick on carbon panels :lol:

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if you replaced the full system and had a power commander fitted and set up you would see that flat spot go and a slight increase in power


but the biggest difference would be the smoothness in power delivery


without it been set up properly you will always have that flat spot or less torque than stock at those revs unless you leave the valve operational

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I think you will need a remap or power comander.


I recently had my EXUP set to fully open since there was a fault with the cables... it was pants below 6k. Pants.


I imagine it would be similar if you just fitted a different exhaust system, bypassing the valve, without adjusting the fuel mapping.

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http://www.skutr.net/exhaust-valves-and-servo-motors-explained/


Ill be leaving mine alone until such a time it becomes a problem then ill decide from there but this makes some interesting reading

 

confirms my findings on my Gixer600. i removed the servo and left the valve open. there was no noticeable power drop, but it sounded much nicer.

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  • 4 weeks later...
The SET valve is actually part of the silencer on a K5/6, so I have discovered, therefore it has to be removed no matter what slip-on is fitted.

 

I do believe that you have to remove a wire from the grey socket on the ECU, or else it causes a failsafe mode!

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The SET valve is actually part of the silencer on a K5/6, so I have discovered, therefore it has to be removed no matter what slip-on is fitted.

 

I do believe that you have to remove a wire from the grey socket on the ECU, or else it causes a failsafe mode!

 

When you remove the SET valve servo, the FI light will come on. you need to pull the wire from the ECU to put the FI light out.

the FI light doesnt slow the bike down, just annoying to have a big red light on the dash.

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I'm fairly certain that certain F.I. faults will slow the bike down, it goes into "limp home" mode if the SET valve is at fault according to the list in the manual.


The Yoshimura instructions come with a decent print-out of what wire to remove, I have the full Suzuki workshop manual for the bike anyway.

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Removing set valve and bypassing wires wont put the bike into limp and wont slow it down and even just leavibg the annoying light on wont either just type it into youtube and there are countless vids showing it

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Yes some faults will, but the SET valve fault code won't cause the bike to go into limp mode. Its just annoying.

According to who/what though?. In the Suzuki workshop manual.pdf, a fault with the servo/valve will put the bike into fail safe or limp mode. I'll disconnect the servo with the Yoshi fitted, then check what happens if I leave the ECU wire intact (just to see). Maybe it's wrong, but here it is in B&W:


11043194_10153109339012889_7417673012753354788_n.jpg?oh=229954f4e85081240b9c1fefb72cfe25&oe=5590D47D

Edited by Matt Strange
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I was wondering, your bike = non chavved!


What is a chavved version? :lol:

One covered in awful relentless or monster energy drink stickers etc, usually owned by mid-forties scaffolders who think because they ride like an utter bellend on the road, they have "skills". Also found in the novice group on track days, sat bolt upright through the corners and being overtaken by teenagers on 400ccs.

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Yes some faults will, but the SET valve fault code won't cause the bike to go into limp mode. Its just annoying.

According to who/what though?. In the Suzuki workshop manual.pdf, a fault with the servo/valve will put the bike into fail safe or limp mode. I'll disconnect the servo with the Yoshi fitted, then check what happens if I leave the ECU wire intact (just to see). Maybe it's wrong, but here it is in B&W:


11043194_10153109339012889_7417673012753354788_n.jpg?oh=229954f4e85081240b9c1fefb72cfe25&oe=5590D47D

 

Read it again. The Fail-Safe Mode is fully open.

so if the valve is not there or no signal is not received from the servo, the ECU will default to the fully open setting which has no impact on the running of the bike.


The FI light will come on to let you know the ECU has defaulted one of its settings to the fail-safe value, but this won't slow the bike down as the valve is non essential so the fail-safe mode value of fully open won't be a problem.


EDIT:

Here's a photo of my GSXR with its FI light on... no lack of power here ;)

155.png

The ECU has simply assumed the SET valve to be fully open (which is is) and which it would be at revs over 5k rpm.

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Yes that tells you what the valve is commanded to do if a fault is present, but the ECU also goes into Fail-safe mode with "minimum performance necessary". I'm sure that & "Fail-safe" are Suzuki Engrish for limp mode.


10414902_10153109575167889_3410124084367845731_n.jpg?oh=a3030db01423dce65e5081312a9c78c6&oe=559660B6

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Here's a photo of my GSXR with its FI light on... no lack of power here ;)

There are other faults which do not put the bike into limp mode, the lists I've posted are faults which apparently do so. They will vary from model to model too, a 600 or a 750 ECU is different to a 1000. A FI error on either may be totally different on a 1000cc and produce different errors or running conditions.


What GSXR & what fault in your picture to cause the light to come on?

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