Clutch mod.....bad news!

[Mikeybikey57]

I know this subject has been done to death so to speak but I do feel that this needs to be seen. I was looking at April's edition of 'BIKE' (UK) magazine this morning and came across an interesting little article.

BIKE have an S10 as part of their long term test fleet, which is ridden in the main by their resident photographer Chippy Woods. Having perused this forum, found the thread relating to the clutch mod and thinking he could detect a whiff of "snake oil", the articles author decided to try it out on their test bike and check out the results on a dyno.

Shock Horror............... the subsequent dyno readings revealed a 2bhp drop in overall power and a minor reduction in torque to boot. They did agree that the bike felt smoother and that the engine seemed pick up more quickly but added that this was due only to changes in the ignition timing, as opposed to any increases in power/torque. It was also suggested that the changes in the ignition timing was also responsible for an increase in fuel consumption but by increasing the amount of unburnt fuel passing out of the engine, rather than burning any more petrol.

So.......does anybody here have any comments / opinions or evidence to either support this article or prove anything to the contrary? ??? ???

 

[The Ferret]

It wasn't a very exhaustive test. They didn't cover the torque and power in each gear. Power is great, depends how its delivered though.

 

[Podman]

What page is article on cause can't find it in April issue.

 

[RED CAT]

Haven't read the article but its sounds a lot like BS. Positively everyone who has done the mod is very happy with the results. If I have less power and torque how come when I drag race my pal on his GS with the mod my bike is faster than his up to 100kph? Without the mod he beats me every time. Must be cause I have less power and torque. Gas milage is exactly the same also either way. 53 mpg Imperial riding aggresively. ::26::

 

[scott123007]

Does it really friggin matter? It's either a $1 fuse or a $8.00 switch. It bypasses the ecu programmed touring mode or sport mode and gives you pretty much a direct link between throttle and butterflies. BFD. It's not like you just spent $1500.00 or more on a PCV, header, slip-on and maybe a reflash to gain 10hp. If it's THAT important to someone, they can put it in sport mode, turn their switch "on" for initial acceleration, and then turn it off after 3rd gear and get their extra 2 hp. Geez, this isn't MotoGP for crying out loud, it's a 600lb pig with 90hp.
,

 

[X5]

Use Your Illusion...

 

[Mikeybikey57]

I totally agree. It's not a WSB bike and whats a couple of BHP between friends. As long as it drives better for you, then there isn't a problem really. Just mentioned it to see what people thought about the article.

 

[Dallara]

Haven't read the article but its sounds a lot like BS. Positively everyone who has done the mod is very happy with the results...

Not "positively everyone"... I wasn't.

Use Your Illusion...

Amen, Bruddah! Amen!


Dallara



~

 

[EJV]

I thought there were Dyno Charts buried in the big Clutch Mod thread?
Showed Gains/Loss by Gear?

Or maybe that was the ECU Reflash Thread.

Not sure, I forget if the Clutch Mod Switch was flipped as I typed this........ ::013::

 

[avc8130]

I have been in contact with a reputable source, whom I will reveal once we have concrete information.

The working theory right now is that the CJM will, in fact, remove the throttle restrictions. However, it also adjusts timing and possibly fuel mapping. More factual info will follow within a few weeks.

With that said. 2hp PEAK is not something I would worry about. The throttle response and extra grunt down low/in the mid range is much more usable.

ac

 

[offcamber]

Haven't tried it so I have no opinion....

my question is....why would Yamaha do it in the first place? Whats the reason for it??

 

[X5]

Haven't tried it so I have no opinion....

my question is....why would Yamaha do it in the first place? Whats the reason for it??

Legal/Safety, Passing EPA standards, Longevity/Warranty...take your pick.

 

[offcamber]

Legal/Safety, Passing EPA standards, Longevity/Warranty...take your pick.

But why does it change because the clutch is pulled in? Why not just leave it "adjusted" for EPA, Safety etc all the time?

 

[Waspworks]

Those that have done it and not notice a difference, or felt a decrease - I can only suggest it was not done right....

As for the magazine that quoted the pile of rubbish that is the subject of this topic - I can only guess they are absolutely full of shit and either didnt do it right, or their bum dyno needs re-calibration because they could not have put it on an actual dyno to quote that dribble.. ::010::

See below the actual recorded figures from runs on our own (Intake-Express P/L) Dyno-Jet dyno.
these runs were done primarily for the purpose of creating a good fuel map to suit my exhaust + PCV, and secondarily to prove/disprove the clutch mod.

Read the run descriptions at the bottom of the pages.
Note no change to 1st gear output.
Mid runs - "clutch mod + zero PCV map" wre exactly that. A zero map (ineffective) loaded to the PCV.

Check out the impact on second and third gears ::012::

Id like to know where Yamaha got the 110hp figure from - This is with a PCV and extremely good maps.

The base run for these was conducted two years ago and the other runs were done about two months ago along with the rest above.

Greg.

P.S - We managed to completely remove the irritating popping on decel, and, the bike is incredibly smooth at all revs now with no/or very little throttle snatchy at low revs.

 

[Karson]

Thanks wasp - always good to toss real results out there when these topics come up. I think JaimeV has dyno runs, too, if I'm not mistaken re: the clutch mod.

anyway- when you weren't running the clutch jumper, you were in S-mode I assume, right?

 

[avc8130]

Id like to know where Yamaha got the 110hp figure from - This is with a PCV and extremely good maps.

I am sure their claim is "at the crank". Shaft drives and 90 degree drivetrains are generally pretty inefficient. I am not aware of any manufacturer that claims HP at the wheel. That would be too easy to prove .

ac

 

[Waspworks]

Thanks wasp - always good to toss real results out there when these topics come up. I think JaimeV has dyno runs, too, if I'm not mistaken re: the clutch mod.

anyway- when you weren't running the clutch jumper, you were in S-mode I assume, right?

Double checked prior to each run = 'S' mode + TCS off...

Greg.

 

[Waspworks]

I am sure their claim is "at the crank". Shaft drives and 90 degree drivetrains are generally pretty inefficient. I am not aware of any manufacturer that claims HP at the wheel. That would be too easy to prove .

ac

Valid point AC. I had a short term brain fart..

Greg.

 

[avc8130]

Valid point AC. I had a short term brain fart..

Greg.

Greg,

Good to see you back. I know JaimeV is giving you a serious run for your money on "coolest Tenere on the block"!

Better up your game and make more cool stuff! LOL

ac

 

[Waspworks]

Greg,

Good to see you back. I know JaimeV is giving you a serious run for your money on "coolest Tenere on the block"!

Better up your game and make more cool stuff! LOL

ac

Dudes WAY cooler than me..

Greg.