Scooterotica

pal of mine has a 125 special with a gori 175 kit fitted, he was suffering with clutch drag, its a standard 4 plate clutch, he has fitted a bgm kit with springs and plates and it still drags, i had a look at it and couldnt see any reason it might drag, oh he fitted a new bgm bush in the basket as well, and a new cable and quadrant, any ideas please ?

Has he got 'fat' grips fitted (e.g. balloon grips) and/or poorly shaped levers (like SIL and late Italian GPs)?

Many 4 plates suffer drag because of cork plates being made too fat for the combination with standard steels and top plate.

If the BGM requires additional lever travel because of a deep crownwheel then anything limiting lever travel will cause issue.

Is the arm on the casing on the correct spline alignment?

... just a few things to check.

Adam

i will have a look at it to see if there is anything obvious, i dont think his crownwheel is cut deep, maybe that could be the problem ?

Insufficient room for separation is the main cause of clutch drag, which can be the result of many factors (some listed previously). Having a deeper crownwheel is one way of addressing the issue, as is fitting thinner corks, fitting thinner steels or fitting a thinner top plate... all of which are available. However, even addressing these can introduce further issues, e.g. fit a deeper crownwheel and you may still find that you have issues as the springs can only compress so far before they become coilbound or fit a thinner top plate and find that you need to bend the tangs of the cop cork plate down so that they don't ride over the top of the basket.

Fitting thinner corks, if indeed 'fat' corks are the issue, is normally the best way to address this... although fitting thinner steels is another good solution.

So many combinations of clutch parts can cause issue... but nice when you eventually get things right.

Adam

as adam says above ,drag is simply a case of not enough separation/free play .

check all the springs are seated correctly, if any of them are not it will cause uneven compression, this will also result in drag.

Thanks for the suggestions, it was a very simple fix, the cable just needed some more adjustment, and no more drag.

I was told that 1.5mm is the absolute minimum gap you should have between the top plat and first cork when fully compressed with a compressor although nearer 2mm might be a tad better. SIP adjustable leavers will give a little more stroke but not everyone likes the styling of them.