I'm doing this mini-article for Dave King but I some of you may learn a thing or two about making the banty clutch user friendly!! Well this is what I do and I like to pride myself on having the lightest clutch lever action in the paddock- thats certain because i've pulled everybodies clutches in!!

Clutch Drum - make/get a new one made out off slightly thicker steel and get a band brazed round the outside oppersite the circlip groove as picture.Pic1 (mine has 12 slots to save weight) You also need a groove all the way round the spring carrier plate for the cirlip to sit in.

Pic1


Plain plates - machine out the centres to about half there width. in Pic2 is a std plate and a narrow one

Pic2


Fricton plates - remove all previous burnt surflex clutch material so the plates become plain plates, and cut groves in with an angle grinder or simular kit. A good way to remove surflex material is give useable plates to Peter T and wait him to give them back with minimal material left, after a seasons hard clutch slipping He may charge you for this service?! Pic3 shows a surflex and 2 now plain plates (1 by angle grinder 1 by a machine of some sort(Ted)? Cut slots before getting plates hardened (if you are going to bother some racers don't - Alan pls comment) The slots hopefully stop them distorting! If they dish a little - no worries dish them all the same way when you build the clutch up.

Pic3


I've heard people say my clutch is slipping, I'll put another plate in! yes this may work but you will increase the clutch drag then they may put another in when it starts to slip again - increasing drag again ... When all they need to do is increase the spring pressure not add plates. The clutch needs to be 'bleddin' hot to work so warm the clutch up before you go on circuit otherwise your first two laps will be severe clutch slip.
Try to use the least amount of plates not the most and start with 6 Heavy Duty springs from Alan Brown or Rex Caunt(on ebay) then increase the number of spings (because they become weaker) or replace them.
I start with 6 then 7 then 8 then 9 then replace springs starting with 6 again. Yes you have guessed it I've got 3 spring plates 12hole (for 6 and 9) and a 7 and an 8. A 6 spring clutch is nice and light. Pic4 shows a 9 and 8 plate (12 and 7 are on the bikes)

Pic4


Hope this helps.... Mike

Great explanation and photo,s Mike .There is also a mass of weight that can be drilled out of the primary drive sprocket and hub the material it
is tough not hard.I will start to play with modifying clutch plates tomorrow .Has anybody used stainless steel pre-hardened clutch plates either water cut or laser cut?I have only used transmission oil are there other opinions using the steel to steel option any notewhorthy benifits.looking forward to the reply threads .In one photo the pressure plate in which the clutch standard mushroom pushes against has been modified ,whats that about?
regards Dave

hi dave your missing the best / most important bit, look at pic 1 again now see top right corner, now can you see how close the spocket s to the casing, now look up and left of this bit and see the original boss for the primary cover screw ! notice anything ??

sorry mike just can not keep a secret all this technical stuff got me all in a tiswas!

kind regards

Derek

oh nearly forgot great post Mike, not sure Inow how to follow that one, not sure I can, any more GEM'S

Ians got 28 bhp - sorry to bring up weight again BUT if Ian has 28 mike you need 30 peter needs 34 and i need 36 to excellerate at same speed as he does acording to Mrs cooks calcs that is, not sure it works like this but still waiting for john, to come back to me on those slimming tablets. ? LOL

Derek

Okay maybe I missed the detail in pic1 ,doesnot everyone play around with primary gear ratios at some time or another;in a 3 speed
gearbox the gaps between gears just get bigger or smaller depending on with you have changed the primary ratio; not much fun riding.Thank goodness for my 4 speed and yes I have used the 3 cr box.
The only other detail I saw was the small end crank seal boss was machined off and recessed a typical mod.
regards Dave

Exactly Dave, a typical mod!....
Doesn't everyone change primary gearing on a 3 speed bantam - No think everyone will be on 17/38!
Rex Caunt does 12and 13 engine sprockets I think?? for trails applications - no good to us.
Don't think anyone has paid for laser cut anything? on a bantam in the UK when you can do it with a hacksaw/angle grinder/file. Stainless steel ? I'm guessing to soft? Clutch mushroom has a trust bearing inside - typical mod in the UK lol
Oil some use AQF/TQF automatic transmission fluild or EP80 gear oil and I use cheap engine oil 10w40 or the like - don't use synthetic oil -clutch will slip.... And get some magnets mounted in your primary case to collect all the oily metal fillings....

Regards Mike

Too confused to understand, but great post. Thanks Mike, I'm also starting work on the clutch; managed to split some of the clutch plates the other day, some haven't been used in over 50 years.

T

Hi Mike you fox " on the end seal boss being machined off, try again Dave.

Derel

Mike, does that mean the primary drive is set in closer without the outer 6203 bearing ?

bearings now ? - shussh ???

"now" john come on I need those tablets been wondering if you been, ignoring me, what about those slimming tablets please ???????????.


out of interest what type of fuel do you use down there john ? 4 start 5 star of Avgas. been looking at fuel cell,s seem the electric bike will soon be forced on us, we should alll strike for a season tke the whole season off teach these do- gooders a bloody lesson, there's power in numbers - ask the fars east dictators look what happened to them, ignored the small man to long and too often


lets stick to banatam racing tuning more interesting ? .

Regards Derek

Spot on John...

003 has a two bearing crank! the primary drive being set inboard a little. Like Derek says a picture speaks a thousand words;but only if you look at it!! (i said that bit!)

So whats the advantage of a 2 bearing crank ? Doesn't it increase crank flexibility, perhaps when we are looking for rigidity ?
Certainly would easier to change the oil seal.

Your picture does not show any primary chain oil guide, been trying to explain to my engineer what I would like, but can not quite figuire out what to attach it to ?

Then oil will not all be thrown up the back of case and I can use less as you suggested.

Day off, no work, got to stain garage door; then I can get some pictures of our clutch mods

John - Just think, do you know of any japanese two-stroke motors with 2 drive side bearings... I don't, perhaps the yamaha copy of a DKW RT125! If honda don't fit 2 bearing on the drive side neither will I. As it happens seal has to be fitted before bearing and can't be removed without splitting motor...

please clarify seal fitted before bearing ? you mean the seal s close to crank bearing on outside ? or bearing on then seal.

are you sure Mike " I thought it was me who said "a picture paints a thousand ? " , I don't want to be a cock about this, but it was me !!. LOL

spent an hr answering all these posts, so had enough now.

regards Derek

You said " A picture paints a thousand words"

I said " but only if you look at it"

The picture has had 172 ? views but how many people noticed what you did? you must have an eye for it?

Well you have since the pic(1), looked at it (2)now imagine and wonder how it was done? (3)

Happy creative thinking..... tell you tonight or tomorrow.....

Its wednesday so busy today...... will be reading MCN