# 2008 Stock Brute clutch weights



## phreebsd (Dec 16, 2004)

got me a scale today at harbor freight. decided to measure my weights.
they are all 67.3g +- 1/10th g
wth?

i'm calling EPI tomorrow to get the lowdown on clutch weights.


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## Guarino113 (Oct 3, 2009)

thats crazy. i think kawasaki just put anything in there


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## phreebsd (Dec 16, 2004)

or they know what it takes to make it better. seems to me, the weights got heavier over the years from 2005 to 2008+

either way im going to research the heck out of clutching and weights. looks like i already got some good ones.

by weighing them, the 2008 racersr (drag) guys know now they can go way lighter on the weights to get more speed.


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## derk (Nov 24, 2009)

Interesting. My stocks are 58g.


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## Muleskinner (Apr 24, 2009)

If you go lighter you will have a higher shift RPM with a given spring. This is with the same profile weight, the shape of the curve has a big effect on things. If you take mass off of a weight you need to decide where to take it from. Closer to the pivot pin affects bottom end and the tip affects top end. Lose tip weight and your top end won't pull as hard. Heavy weights have more inertia and are more resistant to backshifting. If kawie changed the flyweights they also had to change at least one other component in the clutches or the speed the engine makes peak power had to have changed.

When tuning a clutch a mistake many people make is to adjust the engine operating speed with the secondary clutch. This should never happen. Set up the secondary to give the desired type of shift (fast or slow up or backshifting) then once that is acheived go back to the primary and calibrate for engine RPM.


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## phreebsd (Dec 16, 2004)

great post.

i read about what you describe above - the profile of the weight and were the mass is from the pivot point makes a huge difference. im calling and seeing whut they say i need for whut i do


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## Muleskinner (Apr 24, 2009)

That is why I run heel clicker weights. Load the heel with weight and you get incredible low end pull with good upshift and no belt slip and added some weight to the middle to keep a hard pull in midrange. I lost top end but value the bottom and midrange more. They can be set to balance all three if desired.


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## phreebsd (Dec 16, 2004)

ive been looking at these stock weights. best i can tell (using a beam and some math) is that 89% of the mass lies near the pivot point. the other 11% is from there to the tip. being 67 grams each with most of the weight at the heel, that should deliver good belt squeeze. What do you think?

I'm looking to assure the best grip on the belt i can get. Gear reduction will also be added which should totally fix my belt issues in the really really thick stuff.


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## Muleskinner (Apr 24, 2009)

Divide the weight into 3 sections when viewed from the side. The 1/3 with the pin hole is the base and has its biggest effect on bottom end, the middle has the biggest effect on mid range and the tip has the biggest effect on top end. For mud riding I would suggest having the most weight in the base and middle. There is no problem with machining weight off the back of a flyweight if you want but be aware that each gram removed will raise the engine shift rpm around 100 to 150 rpm (depending on the spring) so you may then need a lighter primary spring. I would also suggest having a secondary spring on the heavy side to help with backshift. That way when you catch traction and spike the engine load the engine will recover its RPM fast. Raising the secondary spring tension will also raise the engine shift rpm as it will lower engine load by trying to be in a lower gear. Google "heavy hitter" or "heel clicker" weights to look at how they distribute their weight.


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## phreebsd (Dec 16, 2004)

Dude yer posts rock


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## Muleskinner (Apr 24, 2009)

Thanks, just trying to help. I have got a fair bit of info from here so far, only fair to chime in on something when I can.


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## Guarino113 (Oct 3, 2009)

phreebsd said:


> Dude yer posts rock


yeah everyone has been confused about this whole thing about clutch weights. it still doesnt make any sense to me thoug. lol


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## Bootlegger (Dec 18, 2008)

Dang...that is heavy Steve. WTF is up with there weights? Those are you stock ones...correct? The lighter the weight the more stall you can get outta stiffer springs and get a higher RPM shiftout...but those are the heaviest ones I have seen. The ones outta the 09 Demo was 58 grams.


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## phreebsd (Dec 16, 2004)

was there any marking on them, mark? mine say X1.


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## Stogi (Feb 24, 2010)

Most of the weight on those is in the pivot. That's a huge chunk of it centralized in the rotating mass. 

Muleskinner ..... You was talking about the Heelclickers and the way you can load the toe to make it pull better on the topend... I have a set of 56 gram EPI weights that I drilled and added weight to the toe. It really made them come alive on the top and still have the bottom-mid pull you get with the profile of EPI. Love them and still run them to this day.


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## Muleskinner (Apr 24, 2009)

The flyweights profile affects the shift pattern. If you have a flyweight that has an aggressive profile it will upshift fast regardless of the extra tip weight. The key is that adding weight will affect the shift out (operating rpm) and this must be accounted for by balancing the flyweight mass with the spring tension. The total mass of the flyweight affects the rpm. Where it is located has a minimal affect compared to total mass. If you took the tip weight and moved it to the base on your weights you would lose top end but gain bottom end. The secondary must also have the correct combination of spring tension and helix angle to match up or you may end up moving some slippage to it.


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## Muleskinner (Apr 24, 2009)

For some good information on how a CVT system needs to be balanced, Google "Randy Nouis inside clutch tuning". I am on my Crackberry and can't figure out how to paste the link. It discusses sled clutching but the physics are identical. No magic clutching setups just info on what to change and why.

Here is the link: http://www.sledgear.com/driventech.htm


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## Brute650i (Dec 17, 2008)

I really want to get the vfj clutch kit that way the adjustments for the weights and combinations are endless


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## rlfoulch (Apr 24, 2013)

I know this is am old thread but I'm sure someone here can help out. I have two primary clutches. One I have epi kit with pink spring other has the X03 weights and orange spring and a Dalton face plate. I used 3 to build the two and I was told that the X03, orange, Dalton setup with red secondary would be the best setup for my 05 brute750 with 29.5 ol2 s/w
I also have a yellow secondary if that would be better. 

I don't want to louse any top speed but still want to pull hard when in the mud. Riding will be mixed mud and trails with some hard pack. 

if it weren't for the laws of physics we would all be unstoppable.

go deep or go home. 

2013 Rubicon 4" lift, 3" stretch, home made high lifter style floorboard bracket, 26" s/w laws on steel wheels, K&N filter, sigma stage 3 jets, clipped carb spring, and body drilled, Harley muffler.

05 brute 750 29.5 ol2 on m12 wheels, snorkel your atv snorkel kit, custom rad relocater, full hmf race series exhaust, 4500# winch,


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