MOD: Stock clutch get more bite (simple)

Jayraye39

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So this modification is meant for the stock clutch and clutch spring if you are like me and have upgraded your motor for more power you might be slipping the clutch. Even though you have maxed out your preload you still seem to slip the clutch a tad. this mod will correct that problem however once you get to the point where you start slipping after this modification you might want to look into getting an upgraded clutch. This modification is not a substitute for a more powerful clutch it will just help the stock clutch a bit more. I was in between slipping and non-slipping with a simple pipe upgrade and I didn't want to spend the extra money on an expensive upgraded clutch so this modification helped me until I added 2 more power mods to my motor. In general this modification should hold your clutch strong to about 4-5hp for a 66cc bottom end motor. Although I have not tested it on any other motor it could possibly have the same effects on different Motors with stock clutches.

The first thing to realize about your stuck clutch is it's not very effective .The reason being all of the pressure being applied to the plate is being created by the flower nut in the center. Most of these plates are not correctly true or flat so since that pressure is applied in the direct Center. there is not an even amount of pressure spread out across to the outside of the plate. This is where contact is made primarily with the pads so to correct this. Just simply get a second clutch plate and stack it on top of the first one. Then attach your flower nut and adjust your preload. The reason this works is because the flower nut puts Center pressure on the first plate. That first plate then applies a spread out pressure on the entire second plate. This gives you an even amount of pressure on the bottom plate when it holds up against the pads.

Now this next mod is for the clutch shaft which holds the spring between two cups. Now this mod is not necessary in order to have the first modification work good. However it does help by giving you more adjustment on your preload.

When you adjust your preload you add more pressure to the bite of your clutch plate. What limits your adjustment and Maxes it out are the two cups that hold your inner clutch spring at either end. these two cups when maxed out and your lever is pressed hit one another. So what you can do is take out your shaft and disassemble it take out the two cups and file two to three millimeters or as much as you can off of the cup that does not have the PIN. Please note you do not want to take much or any off of the cup that does have the pin. There's a lot of pressure being focused on that single pin and hole so stick with the empty cup. After you have done this reassemble and you will get a few more turns out of your preload. By doing both of these modification combined will give you the much needed power to stop your slipping clutch. This modification has been tested by me and a few other Forum members with great success please consider before buying a $300 clutch
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Just an FYI Stock nut recommended to modify measures 10mm. I'm shaving 2mm and I'll come back with results from running on a Ported Minarelli.
 
A quick question please. If you get a few more turns of preload by shaving that one cup, could that increased spring pressure on the pin in the other cup cause it to become distorted or bent? Thank you.
 
A quick question please. If you get a few more turns of preload by shaving that one cup, could that increased spring pressure on the pin in the other cup cause it to become distorted or bent? Thank you.
Just shaved one down and doing this with a DLH SAF clutch combonation. Only way to tell is over time!!

Either or with my setup the pin WILL need to be replaced very soon!
 
A quick question please. If you get a few more turns of preload by shaving that one cup, could that increased spring pressure on the pin in the other cup cause it to become distorted or bent? Thank you.
Yes. It can definitely accelerate wear and tear on the pin, bucking bar, and ball bearing inside the shaft. More preload =more seated pressure to overcome. It can also make the clutch pull a bit heavier. It's the price you pay.
 
Well here's 2mm shaved. I'll let you know how it goes.
 

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I went about tightening the spring a bit differently. Instead of cutting the collars or tightening the collars completely, I added a washer(s).

After trials, I ended up using one washer but I do run the RDM pressure plate and a mix of RDM hard pads with the white/black stripe CG pads.
IRC, the washers measure 27.5mm OD x 20mm ID. They fit the clutch shaft exactly.
They were cheap…ebay... $3.75 shipped.


The thing about spring compression is at some point, more compression will not give more force.

I occasionally deglaze both sides of the pads and outer plate. This holds sufficiently well.
With all this extra hoopla I can still slip the clutch if I abuse it.
 

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