Basket Cases

[Phil 850]

I suspect Greg is correct.
Why don’t other manufacturers do it. The difference may be quite small and with a bit of wear of the parts it will likely even out fairly quickly.
When considering the clearance of the cam shaft in the hub, accuracy of the two shoes being identical (not) the extra effort in making the cam asymmetrical is not worth the effort.
Worse still, is the problem when maintainers don’t read the manual and fit it backwards which then exacerbates the issue.
If wanted to do it properly, the cam would have been “keyed” to prevent incorrect assembly.

Phil

[David Lahey]

I suspect Greg is correct.
Why don’t other manufacturers do it. The difference may be quite small and with a bit of wear of the parts it will likely even out fairly quickly.
When considering the clearance of the cam shaft in the hub, accuracy of the two shoes being identical (not) the extra effort in making the cam asymmetrical is not worth the effort.
Worse still, is the problem when maintainers don’t read the manual and fit it backwards which then exacerbates the issue.
If wanted to do it properly, the cam would have been “keyed” to prevent incorrect assembly.

Phil

The asymmetry of shoe wear that inevitably develops sounds like a good reason to always put your shoes back in the same way if you take them out

[JC1]

Dave, I'd have answered like Greg did, as you probably thought too.
As to why other manufacturers don't do it I'd have simply said, too slack.

Or perhaps more to the point, when the front brake is setup the right right way it doesn't matter much.

Here's an interesting point. Bearing in mind that a single leading shoe brake is most effective when the leading shoe is the one pushed further against the hub (ie by the inside edge of the cam/actuator if it has the same profile both sides, as was pointed out in Greg's post), countless models from lots of manufacturers aren't set up that way. Almost as if they were not aware of that. Bultaco owners take note on their early models with full width hub. (Sorry Graham!) But they are far from alone. Cotas & early MARs are in the same boat. It's a major reason why they all have weak front brakes, made worse by short actuating arms, the very heavy flywheels of the day and no-clutch riding technique. With that system you effectively don't have an active leading shoe... unless you're going backwards!

The KT is also set up that way and it seems that Kaw tried to compensate with the asymmetrical profile so that both shoes are pushed out about the same amount. The asymmetrical profile makes a noticeable difference, especially noticeable (by comparison) when you turn it around the wrong way. Part numbers show the same part is used on scores of (long running) small Kaw models starting with the 1967 CS2 120 roadie. When I checked several of those models which use that actuator they all have the front brakes set up with the trailing shoe pushed out by the inner edge of the actuator (as on the KT).

The reason a brake works best when the leading shoe is pushed out further (ie when actuated by the inner edge of the actuator) is that, once the leading shoe is engaged with the hub the rotation of the hub tends to pull the shoe into the hub's surface so it bites in so to speak. Whereas when the trailing shoe is the one pushed further into the hub, the rotation of the hub tends to pull the shoe away from the hub's surface so it doesn't 'bite in' and it's not nearly as effective because the critical leading shoe does little.

Honda TL/TLR and Suz RL front brakes were set up the 'right way' as are the later Sherpas with the conical hub. Some of the later MARs appear to be too.


Be interesting to see if Kaw used an asymmetrical actuator for the rear brake too. (It's a different part no.)

As it's set up like the front brake, with the inner edge of the actuator pushing out the trailing shoe. (So are TY brakes by the way.)

[Greg Harding]

Hi Everyone,

Be interesting to see if used an asymmetrical actuator for the rear brake too.

PS Had to leave posting here in a hurry, so its incomplete. Will finish it off tomorrow sometime

Yes John, they do and we need to remember we are talking Miniscule.
OK, so I have consulted the Brains trust and here is their reaction:

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Finally! They said.........................

Then they went on to say that KAWASAKI HEAVY INDUSTRIES is a long running joke as EVERYTHING is heavy to them........

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Anyway, your offer to swap for RL parts is very tempting. I have an RL engine, forks and a Suz front wheel with a slightly larger dia conical brake that I think would suit, but I'd need everything else:
frame, triples, swingarm, rear wheel and brake, tank, seat (or seatbase), airbox, carb and a lot of the little parts.

Let me see what I've got to swap

So John, what have you rounded up from the mancave?

[JC1]

See below Greg

But first, I completed my previous post above in answer to Dave's question about the KT actuator profile, so it makes more sense now.


I found a fair bit of surplus trials stuff for your consideration Greg. Here's a few pics.

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Italjet frame, swingarm & bashplate. Rear wheel brake surface is very pitted. Airbox has several cracks.
(I'll need to keep the triples)

KT exhaust has hole in the bend of the header. Rear muffler has no baffle. Airbox is OK.
KT Engine is complete, with CDI stator and flywheel but don't know what condition. Bigend is shot. Kickstart lever has been tack welded to shaft (by PO).
2 extra KT barrels and 1 extra head which has one stripped plug thread. KT carb attached.
TY250 engine. (B model I think) Rod is bent. Sidecovers are A model. (Actually, I'll need to keep the clutch-cover, clutch and primary gear for my TY project)
138 Alpina cases and crank.

I'd still like to see the Italjet/RL project completed but I really thinks it'll be beyond me.
Need a hybrid project yourself??

[Greg Harding]

Hi Everyone,

Would you be interested in a GENUINE RL 250 frame? As David says, I am always interested in trading / swapping parts.

Anyway, your offer to swap for RL parts is very tempting. I have an RL engine, forks and a Suz front wheel with a slightly larger dia conical brake that I think would suit, but I'd need everything else:
frame, triples, swingarm, rear wheel and brake, tank, seat (or seatbase), airbox, carb and a lot of the little parts.

Let me see what I've got to swap

John, here are photos of the parts you have requested:

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Since those photos were taken, I have had a bit of a rethink and here is a photo of some other parts I think you will need to build a complete RL 250:

1623058185026.jpg (92.21 KiB) Viewed 748 times

If you are happy to swap your eclectic collection for my parts then so am I. It will be really good to see another RL 250 up and running!

[JC1]

Been a bit slow returning here

Looks promising Greg

Would you have a spare TY250 rear wheel (with brake, axle, adjusters and sprocket if possible) to include in the swap as I need one for my project TY250?
cheers, J

[David Lahey]

A few years ago there was a series of postings on here about making the clutch action lighter on KT250s and one of the things I did was to fit four TY175 clutch springs instead of six KT250 clutch springs. This slightly reduced the force on the pressure plate. It went all good and dandy until I rebuilt the motor recently and rode in a trial that needed second gear and a lot of mumbo in a section. The clutch slipped at just the wrong time!
The extra oomph from the rebuilt motor made enough difference that the clutch just couldn't quite handle it.
So now it is back to the six KT clutch springs again.

[David Lahey]

I've been on leave from work and managed to get a bit of workshop time and one of the jobs was to replace the original exhaust on a TY250 with a WES chamber and a new stainless steel header. The original header was getting very thin-walled and had pinholes and the temptation to fit something new, light and shiny was just too great.
Unfortunately my original intention when buying the header pipe was to buy one that would mate up to the Yamaha main box. Later I bought the WES not really knowing which bike it was going on and hoping it might fit the KT 250 somehow or the Majesty 250. There are sidecover brackets in the way on the KT and the header doesn't run close enough to the head on the Majesty so it was destined to go on a TY250.
I didn't know it at the time but that header I bought has the top run at the wrong angle for a WES chamber. I had a TY250 motor nearby so attached it to a bench and used it to hold the header while I reshaped it to fit the WES. Being stainless steel it didn't take much heat input to get it soft enough for the shape change.
The bike had been jetted for a standard header and chamber and a WES end muffler. With the new header and WES chamber and WES end muffler the idle air screw needed to be moved a quarter turn inwards to get it running nice again.
The sound is quite different. You can hear more of the combustion happening but overall I don't think it's any noisier.
The main difference in the bike is the handling. It feels noticeably lighter to ride. I did weigh the parts before fitting them and the new header and WES chamber was about 1.5 kg lighter than the Yamaha header and chamber that came off. I figure it will gain weight due to the packing getting wet with oil but for now it feels great.

[Guy53]

When I bought my Wes exhaust to replace the original Yamaha on my modified 250, I forgot that I had to ''fit'' it, the head pipe would be in the way of the gas tank so I had to make my mind about replacing the tank or modifying the pipe. I measured and cut the head pipe at the welded seem, cut a taper slice of it to fit hoping that it would not change too much the low end torque. I'm very satisfied by the result, good power band, and yes it does feel lighter.
Guy