Custom clutch springs...

[SpannerMonkey]

The clutch springs on my PC50 are giving way, Anything even SLIGHTLY above idle nudges on the back wheel leaving me with no usable torque for pulling off... Honda dont stock the springs as a spare part... Can anyone recommend somewhere where I can get hold of custom springs? I'm after a service where I can send them my springs and say what I'm after... and they do the technical stuff and hand me shiny new miracle springs to use...
Anyone know anywhere?
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[MickC]

Not sure on that mate but there is this on ebay

https://cgi.ebay.co.uk/Honda-PC-50-Engine-/280690328143?pt=UK_Motorcycle_Parts&hash=item415a72824f

Might be worth getting it an seeing if there are any usable bits on it
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Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1

[SpannerMonkey]

Naaa, No point going second hand, it's like a step backwards... I want this bike to get BETTER... not equal or worse...
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[ThoughtContro...]

What number and size of springs do they have to be? I've got 4 CBR125 clutch springs out the back doing nothing, that you could have for nowt of they're any use.
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Prize cunt
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"In a world of universal deceit telling the truth is a revolutionary act" - George Orwell

[SpannerMonkey]

Not 100% sure yet, Will be taking a look tomorrow
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[ThoughtContro...]

They're 19.1mm diameter an 38.6mm long
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Prize cunt
--
"In a world of universal deceit telling the truth is a revolutionary act" - George Orwell

[Vincent]

Are you sure the springs are the problem? You got the right oil? Springs have a specific "tollerance" in length. Once the spring measures less than the limit, it's time to replace. You need to find out what the tollerance is, (usualy in the workshop manual), and measure yours.

Appologies if you know this already.

[ThoughtContro...]

[SpannerMonkey]

Being a haynes manual from the 70's it doesnt go into that much detail, heck, and 70s tech applies, for example, 'the output from the flywheel generator can be checked only with specialised test equipment of the multimeter type, it is highly unlikely the average owner/rider will have acess to this equipment' hmmm... It also says 'honda do not supply any clutch centre parts stating that the assembly must be matched and set to operate at the correct speeds, thereforea complete assembly must be baught if any faults are found'
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[SpannerMonkey]

I just twigged on, you guys think im on about a plate clutch! Its a centrifugal unit. Like a scooter =P hence the need for custom ones.
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My bike? A YX140 powered one-off Monkey Bike, something a little different!

[Vincent]

what do they look like? get some pics up.

[Teflon-Mike]

And being a centrifugal clutch, the problem is as likely to be the clitch slippers as much as the springs.

Think about that Haynces comment about the masses being balences so it flies out to grip at the right rpm.... actual slippers are like a brake shoe, as they wear through slip, they loose mass, right? Also the clerance between slipper face and drum increases.

and little bikes with centrifugal clutches, slip a LOT.

Though in your case forty year old example, the springs, having been left in tension for umpety years, will have relaxed.

I'd pull it, do some measuring, and be asking pertinent questions of the purveyors of pit-bike or mini-moto bits, personally, for some slippers and new springs.

You can get springs custom would, but you are talking a lot of money. British Springs (Redditch, I think) make a lot of automotiove springs, and do a lot of the suspension 'kit' springs, for the catalogue people... but pretty sure they have a full catalogue for automotive & industrial applications.

If not..... down to measuring the length and rate of the springs you have... length you can do with a ruler, (as diameter) rate, like in GCSE Science... hang one on a nail, then hang a pop bottle on the end with a bit of string, add water to pop bottle at the rate of 1Kg or 9.81N per litre, and measure how many mm of stretch you get per N or cc of water....

Add 'a bit' to the rate for relaxing, take a bit off teh length for stretch.... then google springs, and see what catalogues you find, and what in them has similar specs..... buy & try.
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