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ND4's Bulletproof clutch mod

16K views 34 replies 8 participants last post by  Np214 
#1 · (Edited)
Not sure if anyone else has done something like this but i figured id post up my new clutch setup and mod. In classic ND4 fashion i like to make things reliable so here we go. (you can skip below the second === to get the mod)


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Backstory: I finally rounded out my bbk with a finbro superhead that i ported n polished up myself. Things are running amazingly good. The other day i missed a shift between first n second at WOT, wound it out to 12.5k and dumped it back into 2nd and was appalled at how much clutch slip there was, probably around 1.5-2 seconds before it fully grabbed (this was with EBC "10% stiffer" springs and the stock clutch plate). So i set out to get ye ole standard billet clutch plate and much stiffer springs.

I ended up with this

Honda Grom/MSX125 Billet CNC Clutch Plate Kit [WCR] - $49.99 : The Sic Shop, Stunt Parts Store

with 6 finbro springs. 67ish shipped for a nice billet piece and 6 MUUUUUCH stiffer springs.

So the other night i popped it in and took her out for a spin. Clutch grab was INSANELY better, lever pull not any worse than my other motorcycles, but you can actually clutch up a 2nd gear wheelie with ease now and full rev limit clutch dumps have almost zero slip.

Then i took a shit, and a shower, which allowed me to think (this is never any good).

This billet plate has identical tabs for all 6 spots which include a hole for one of the 3 stock bolts. I never liked how 3 of the springs were not captured by a bolt on either a stock or aftermarket clutch plate especially considering how much stiffer these new springs were. So i decided to change this.
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The stock pressure plate has 3 of its 6 spring standoffs threaded for 3 M6x1.00 x 20mm flange bolts. The other 3 standoffs just so happened to be already drilled with the right sized hole (a smidge under 5mm) to be tapped for M6x1.00 threads. In combo with my new billet plate that had each spring tab with a hole in it, things could work out well for a 6 bolt clutch. So i pulled the side cover back off. Pulled the clutch out of the bike so I could tap the predrilled unthreaded holes with an M6x1.00 tap i borrowed from a buddy. Went to the hardware store n picked up 3 M6x1.00 x 20mm flange bolts and then bolted everything back together. Now every spring is properly captured. There is no extra stress on the ears of the clutch lifter plate caused by springs not being properly captured and i feel much better now.

I did not take any pics of the disassembly or tapping process, but any clutch disassembly video will show you how to get to be able to pull the pressure plate out. But here is the final product. 3 OEM bolts and 3 new bolts properly holding the clutch all together in one big happy grippy family.

Auto part Engine Clutch Disc brake Automotive engine part
 
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#3 ·
Good to know they won't have to be drilled out anymore before running a tap through it. Seems like a common sense mod that anyone with an aftermarket plate should be doing.

Thanks for doing this before I bought mine... think I'll be doing the same thing considering how often I drop the clutch!

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#6 ·
If the Hayabusa Springs are a lot taller than the stock springs, its not going to work because they'll bind before the clutch is fully disengaged. When you lock the three clutch plate bolts down, you'll hardly see a gap between the coils of the spring. Once you put the clutch cover back on, you'll know immediately when you go to test it out. Your clutch lever will have a bit of "play" then feel very stiff...don't try to force it.

HOWEVER....If it works, let us know! Share the part number.
 
#11 ·


Busa (part# 21413-24f10)
29.8mm long
2.28mm wire diameter

Stock
27.72mm
2mm wire diameter

Hmm, guy said he’s been running them for a while now. Though after measuring, I could see their size being an issue. Glad they were cheap, $13 for all 6. I wanted to try them out of curiosity anyways. I’m already running 6x kitaco 60% springs on the stock clutch pack(with 24,4** miles on them) and it grips nice an tight!
 
#13 · (Edited)
That looks like it would work. That's a pretty good deal for just $13!!! Let us know how it works. I was looking into the Kitaco springs myself.

Thanks for posting up the part number. I noticed it was for the 1999-2000 Busa. I think I only looked at 2001 and newer busa springs, and they're much longer.
 
#14 ·
Finally got to ride with my rsc lever. I can finally pull the clutch comfortably(though still on the stiff side) with just my index finder. Used to use my middle finger(mostly) and my index finger. Thats with the 6x 60% kitaco springs(on stock clutch pack with 24,533miles on it and a drow sports spring plate) and I really like the way it feels right now. Not gonna be swapping the springs too soon. Gonna throw in a SMR 6 plate clutch pack in at the same time. Should have crazy reliable kung fu grip for a long time.

I go guess long story short. The kitaco springs are nice. All six is very stiff on the stock lever, everyone that tried it on my bike side it was too stiff. With my short rsc lever it’s still stiff but not too much. Most people would probably just run 3 of them, unless of course they prefer a stiff snappy clutch.
 
#23 ·
Placed my order for the clutch plate and 6 finbro springs today. Left a note asking for the 6 hole version, they sent me back an email saying that the 6 hole ones are on back order... still waiting for a reply on timeframe.

Good thing it's winter... and riding is temporarily on hold.

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#25 ·
I just got an email back, West Coast Raceworks is who makes the 6 hole version, they do not know when they are making more. So I'm just going to take the 3 hole version and put it on a drill press and make it a 6 hole.

The sic shop is always good to deal with. They had the best price on this and the customer service was great.

This was the weather last week...


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#27 ·
We were in single digits for a few days, overnight negative temperatures. It's rough.

Anyways, I took my Grom apart today, to tap the other 3 holes. I found that after fully tapping them (normal tap not a bottom tap) and I am going to need slightly shorter bolts. Only 3-4 mm difference, haven't measured exactly. They all stopped at the same spot.

They did tap very easily on the bike. Held the brake and left it in gear, worked fine. The clutch plate and springs shipped out today. Quick date with the drill press and we'll be all set.

Every time I look at the oil spinner, I remember that I really need a Kitaco cover...

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#34 ·
If you have billet 3 hole plate you'll be just fine.
I understand why ND is doing it if he has a 6 hole plate to start with, it's nice, I'm convinced it is bulletproof and probably the best solution, I'm just not sure you NEED 6 holes AND billet.
My stock 3 hole plate has been doing fine on my 4 valve setup with Kitaco springs.

The Takegawa slipper cluth plate is cast but has 6 holes to begin with and is relatively cheap at 30-35$.
Part number 22361-K26-T01
 
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