Ty 250 Clutch Cable Too Long

[billm]

Hello All,

I bought a TY250 some time ago as a non runner and over a few months have got it up to reasonable scratch mechanically and have even wobbled around a couple of twinshock trials on it. I have come across a problem that I can

[bengtphorqs]

Bill, I feel your pain. Just went through that issue myself. The boys at B&J supplied a first class cable for me and it does have an additional adjustment on the cable. However, if you pull the flywheel/magneto cover off, just above the shift lever you will see the clutch adjustment screw. Loosen the lock nut and using a phillips screwdriver adjust the screw until the clutch lever under the motor is parallel to the crank. (It's kind of an eyeball thing at best.)

I'm sure there are more qualified folks than me that can weigh in on this, but I just went thru that this weekend and was able to get the clutch adjusted to my satisfaction.

[feetupfun]

The clutch hand lever might be of a type that has the nipple hole in a different location relative to the holder for the cable outer - levers and mounts are not all the same

You did not mention adjusting the actuating arm angle (the arm under the gearbox). It should be at 90 degrees to the cable when all the slack is out of the mechanism - the adjuster is near the sprocket

Springs:

The springs may be a later type that do not have the same free length the same as originals. Yamaha do that with their spares sometimes. Or they may be sagged due to age. If it was me and it was working fine I would leave it alone but everyone has a different approach to fiddling with their bikes.

Some people (me included) run only three standard springs in TY250 twinshock pressure plates.

[woody]

If you have bought a Venhill cable (I assume so as Yamaha originals are no longer available) then the chances are the inner cable is too long as that's the way they are. I've been through it myself. Even if you have original Yam type levers. The eccentric clutch arm adjuster won't get rid of the play. I had to make a collar that sat in the outer cable locater under the engine which moved the outer cable further away from the clutch arm which in effect shortened the outer cable.

[billm]

Thanks both for the quick reply, I did try and adjust the actuating arm but with little success. It does not sit at right angles with the cable as Feetupfun suggests but instead points forwards slightly towards the front of the engine so this could be part of my problem. I screwed the adjusting screw in until it stopped but all that happend was that the actuating arm moved downwards away from the block exposing about 5mm of the shaft that goes up into the gearbox casing. The acuating lever did not change position either towards the front or rear of the block?? I have to admit I am not sure how to do this adjustment and my manual is a bit vague so am I doing it wrong or does this point to a problem with the adjustor or clutch release mechanism?

Cheers

Bill.

[billm]

Sorry Woody our replies must have crossed in the ether.

It is a Venhill cable as is the one that came with the bike so perhaps that is the answer. I think that unless the cam adjuster has a miraculous affect on the cable then I will shim out the outer cable from the locator at the bottom of the engine with some small washers. I'm still a little concerned that when the cam adjuster is screwed fully in it pushes the actuator out of the block is that a sign of a problem or is that normal?

Cheers

Bill.

[richty250e]

Also worth checking that the clutch release axle wedge (where the wedge shaped cam on the arm hits the end of the pushrod inside the gearbox case) hasnt got damaged. Mine had a lump of case hardening missing on the edge which contacts the pushrod. This will also give you a notchy clutch action. I ended up fitting a NOS part.

To do the adjustment: loosen off the adjustment screw locknut. Turn the screw clockwise lightly until it stops (do not force it further). Now turn the screw anticlockwise and note the position of the release arm.

The total range of adjustment is only half a turn. On the end of the adjustment screw is a pin which locates in a groove in the release arm. The pin is offset in relation to the centre line of the adjuster screw, so as you turn the screw it raises or lowers the release arm by a few mm. When the arm is at its lowest point the thickest part of the wedge is in contact with the pushrod. So to eliminate play you turn the screw till it moves downwards and touches the pushrod, then back it off a little and tighten the locknut.

It sounds like you had it in the lowest position but still had the problem.

Edited May 3, 2010 by richTY250E

[feetupfun]

Maybe the problem with the Venhill cable length has been fixed since Woody bought his cable because I recently bought a Venhill TY250 twinshock clutch cable (through John Cane) and it worked without having to use a spacer (on my standard lever, original clutch plates TY250A).

[woody]

Let's hope they have - when I put my Venhill cable and the original cable next to each other the problem in length was obvious. Happened to me twice and my mate had the same problem. This was a couple of years ago.

[billm]

Both my cables the one that came with the bike and the new one were made by Venhill and they are the same length 1220mm inner & 1120mm outer, the new one came from John Cane only last week. I reckon that if the inner was shorter by just 1/4" (6.35mm) relative to the outer then that would make all the difference. It would be useful to know what the original Yamaha cable length was but I would imagine that there are none of those around now..

I will follow RichTY250E's guidance and try the cam adjuster again today and see if I can get the actuator at 90 degrees to the cable but even then I don't think that will account for 6.35mm because although it sits slightly forward I reckon it's only 2 or 3mm.

Thanks for all the comments and advice so far.

Bill.

Edited May 4, 2010 by billm

[marky g]

Venhill were known for this problem years ago, I had it myself with one of my old monos

[billm]

Just to close this out I adjusted the actuator free play using RichTY250E's guide and reckon that's pretty well spot on but it made no difference to the slack cable. In the end I followed Woody's advice and inserted the cable outer through a 1/4" long aluminium collar down at the cable stop under the engine. This effectively shortened the cable by that much (1/4") now it's exactly as I would expect with the lever adjuster turned out about an 1/8" and the free play at the lever at about 2mm with the clutch operation much improved.

I still can't explain why this mod is necessary except to agree with Woody and Marky G that the Venhill cable is too long but to counter that feetupfun bought his Venhill cable recently from John Cane as did I and his is OK with no additional spacer???

Thanks for all the comments and advice.

Bill.

[woody]

I found an original Yam cable tonight as well as a Venhill cable (neither is in useable condition) The inner cable of the Venhill is a few millimetres longer than the standard cable and it still had the collar I made fitted to it. Then just to really confuse I found another pattern clutch cable and the overall length of this one was several inches longer than the original with the inner cable being about 10mm too long on this one. So neither pattern was the correct fit. The original Yam cable also has an adjuster on the outer cable at the clutch lever end which enables much more precise adjustment of the cable.

Unfortunately Venhill do get the lengths wrong, my KT clutch cable is too long in total length although inner/outer ratio was correct. The clutch cable for the 330 Montesa was wrong, the f/brake cable for the 330 and 350 Montesa is way too short. (they've since corrected the 330 cables as I sent them originals as patterns)

Throttle cables for the Ossa, Bultaco etc for Domino sidepull throttle to Mikuni carb can be a bit hit and miss in length, inner and outer.

[billm]

Both my cables the one that came with the bike and the new one were made by Venhill and they are the same length 1220mm inner & 1120mm outer,

Woody, sorry to be a pain but can you give me the measurements from your original Yam cable so I can compare it to the new Venhill cable, above, that was bought last week. It would be interesting to know if Venhill are still making them too long.

Cheers

Bill

[woody]

Overall length (ie; inner cable) is 106cm

Inner cable is 8.5cm longer than outer.