Greetings.
I have an issue with a track/ race mc28 bike that I currently prepare and I hope someone has an idea of what's happening as I'm scratching my head for two days now.

Clutch handle lever and cable are adjusted to their maximum position and there is still a need of more travel to disengage the clutch.

Specs :
5 fibre plates, all the same (no plate with dampers).
6 steel plates, all the same (no thin plate equals +0.9mm at the total thickness of the plates).

Some photos that might be of help?
First photo shows that the last steel plate protrudes from the inner hub (about 0.7mm). One steel plate is thicker so it looks normal to me.


Second photo shows that the push rod top hat is quite recessed into the pressure plate (about 3.7mm).
Pressure plate completely clears the basket.
Ignore the wet clutch plate, makes no difference with a dry clutch one and they have exactly the same dimensions.


Clutch lever, push rod, 1/4 inch bearing ball and top hat have NO visible sign of wear.
I have swapped clutch cables, levers, handle brackets etc and the problem remains.

I do not have a thin steel plate to test if it would solve the issue but removing a steel plate did solved it.
I fabricated and installed a 2mm metal shim on the push rod hat and everything works fine but obviously this shouldn't have been a necessity, should it?
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In what order did you install the plates ? Fibre first or steel first ? Do you have that tapered ring in there too ?

How far do you have to pull the lever before it moves the arm under the engine , you can adjust the cable there too .


Last edited by Neal on Tue Mar 27, 2012 8:12 pm; edited 1 time in total

First and last plates are steel. They are 6 in total so can't be installed otherwise.
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Yip .

Did you do a dry clutch conversion to this bike or has it had the dry clutch all along ?

I'm sure you have probably checked but is the pushrod the correct length?

Yes Neal, you are correct and haven't mentioned that.

This bike used to be a SE once but came to my hands with most of the transmission parts out of a mc16 engine.
I removed and thrown to the bin all of the transmission parts.

Kept the crankcases, installed new bearings and a mc21 gearbox plus the dry clutch.

I'm not really sure of the tapered ring you are mentioning? Isn't is only a wet clutch part?
Cable is at the maximum position on the clutch cover and at the handle lever as well.
With the lever completely pulled, the top hat just barely touches the pressure plate, almost no existent move, you just feel it at your hand that there is contact but no visible movement at the pressure plate.
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Paul, push rod looks to be correct.
It's the common dry clutch 8mm push rod that ends to a 6.5mm OD for the last 20mm of it's length.
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2Tracelab wrote:I'm not really sure of the tapered ring you are mentioning? Isn't is only a wet clutch part?

Indeed it is.

Check the cable and it's crank case bracket are correct, I don't know about the MC16 but the MC18 is different to the MC21 and MC28, the difference is made up with the bracket that attaches to the crankcase.

If someones mixed parts that may be the issue.
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fontyyy wrote:
Check the cable and it's crank case bracket are correct.

I'm trying to find a photo of it but I can't.
A spacer of about 10mm behind this bracket, will make the clutch disengage properly.

I've tried both mc21 and mc28 cables and there was no real difference.
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I had the same problem and used a stack of washers behind the crankcase bracket with a longer bolt to get the correct lever travel back.
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Hermit wrote:I had the same problem and used a stack of washers behind the crankcase bracket with a longer bolt to get the correct lever travel back.

You mean you had a similar issue while using stock plates or by using a thicker steel one?
Here is the bracket that I have and looks to be the correct part.


Indeed, some spacers behind this bracket will make the clutch cable work properly, it was an option prior preferring to use a shim at the top hat.
Using shims is normal on Rs250 engines, I need to know if it's normal on Nsr clutches as well or something slipped my mind during the installation.

Thanks everyone for the info.
P.s By the way, the aforementioned bracket bolts on the clutch cover, not the crankcase.
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I bought the 'dry clutch rebuild kit' from Tyga: http://tyga-performance.com/site/index.php?cPath=72_1036_79_121_123

Which from the website description sounds like its got some none standard bits to prevent clutch slip.
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Just found this post , I have exactly the same problem with my clutch cable ,the push rod spacer has to travel too far to push the pressure plate , I had the bike at a mechanic I thought was capable to do a full engine rebuild , but turned out to be a monkey, his solution to this was to leave plates out ( from the new Tyga kit I supplied him with) . Firstly does anyone know what length the push rod should be ? Secondly how did you solve the issue ? It seems my bike has been pieced together by various others over the years , so it wouldn't surprise me to find the wrong parts in there .( mc21 carbs with a float in one of them that doesn't fit at all????) I'm thinking it could also have something to do with the clutch arm, that the cable attaches to, does anyone have a pic of it that shows some detail ,as none of the breakdown images are detailed enough to show how it should be.
Cheers fellas

Standard dry clutch rod is 220mm, at least my one is! You will probably find your rod it too short !

Cheers
Mario

Mine is 205mm , thanks again Mario