Question Re. 250 Brake & Clutch Lever Ratios (Perch Fulcrum Distance)

[ranton_rambler]

Can I deviate this thread a little by asking clutch cable routing? As mentioned my clutch is quite heavy and I was looking at my stock of cable bits to see if I could make a new cable. In doing so, I wondered about altering the routing a bit.

At the moment, it goes over to the right side of the bike and curves round under the tank and then downwards to enter the hole in the crankcase from the left side. It's a narrowcase motor so has the short operating lever inside the selector cover. This route seems to be how most of the photos in the Mick Walker books show the clutch cable.

An option looks to be to curve downwards staying on the left side alongside the cylinder barrel and then curve inwards into the crankcase hole. My main concern is whether the cable will stay away from the barrel fins enough to avoid melting it.

Ian P

[themoudie]

Aye Ian,

On my '74 450 MKIII, I used to route the cable from the threaded crankcase casting, out to the left, looping back over the top of the cylinder head, using the wiring clips on the right-hand side of the frame spine, exiting from beneath the front of the tank and arcing around beneath the headlamp brackets to the clutch lever that is an aftermarket Tomaselli period item. Clutch action was "heavy" and others who tried it, queried the routing of the cable, which was as it left the factory!

Last year a touch of arthritis in my left-hand basal thumb joint and riding the old bird just exacerbated the inflamation. Having already fitted a Lacey revised clutch plate kit, along with silver soldered clutch spring pillars in the hub after one snapped off and came through the clutch cover at 60 mph, I still struggled with obtaining a light smooth pull and getting the clutch to free completely when the lever was pulled in.

I re-routed the clutch cable to the left of the cylinder, passing in front of the frame front down tube, but tied to it, then looping back up in front of the headstock to the clutch lever. To date I have not had a problem, with melting it against the cylinder. Using a nylon lined outer casing, with graphite dust (obtainable from a lock-smith for dry lubricating locks) dusted inside it when assembling the cable. This eased the pressure required to disengage the clutch, but it wasn't disengaging fully. So, with advice from Nigel, I removed the friction material from the face of the friction plate at the base of the stack against the clutch basket. This transformed the clutch action, enabling it completely disengage.

I do like the look of the brass tube modification to tidy up the cable run around the cylinder and this type of fitting is used on the Yamaha XT600E 3TB engine engines, where the cable loops around the electric starter motor.

Good health, BillR

[Bevel bob]

Hi Bill , when you talk about removing friction material from the innermost plate ,are you reducing or removing ?. I have seen the result of steel on steel in a clutch ,its not pretty !.

[themoudie]

Aye Bob,

Removing. No sparkly bits in the oil, so far. I'll have a wee check at the next oil change, as you have put a wee brain worm in my head.

Out for a canter today, to warm the oil.

Good health, BillR

[Bevel bob]

Recently worked on 2 Norton clutches where owners had put plates in wrong order , There were metal shards spread all round the primary area . Probably made worse by lack of any oil . I would consider thinning plates down in a clutch like Ducatis which had no built in way of adjusting the spring pressure . I have used small washers to get the clutch to spin true when lifted.

[Eldert]

no harm in removing the friction material from the back of the first plate in . the friction material does nothing

the tangs on the plate keep the plate in place so no rotating steel over steel .

Eldert

[Bevel bob]

Thanks Eldert, thats usefull to know . my Lacey clutch could use a bit more clearance when lifted . Ridden conservatively now slip is not a problem.

[ranton_rambler]

I had a fiddle around with the clutch cable today. Once removed the cable itself was very stiff to move. I pulled the inner out and could see the reason - there was a broken strand somewhere close to the gearbox end which had partially unwound over almost the full length so it had been filing the liner away. A whole load of white plastic shreds came out when I pulled the inner out.
I had enough bits lying around to make up a temporary cable, which I have routed round the left side of the motor. Action feels nicer and is a bit lighter too. When I get the proper replacement I may try going round the other side of the headstock as I think it will be a gentler curve.

Test ride tomorrow or over the weekend hopefully.

Ian P

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[themoudie]

Aye Ian P,

Absolutely route the clutch cable via the right-hand side of the headstock, then poke it up behind the headlight shell, over the top of the left-hand headlamp bracket and up to the clutch lever.

I just nipped out and took an image, then highlighted the clutch cable, with a white overlay, it's attached.

Good health, BillR