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1974 TX500A Clutch(?) issues


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I have a 1974 TX500A as the title says, and the clutch wont disengage. It happened while riding a few years ago. Shifted to first at a light with the lever pulled and it stalled. Ever since that day the clutch wont disengage the tranny. Have inspected the plates and measured everything seems to be in spec. The basket moves upon pulling the lever, however when its adjusted to allow that to happen, the kick start wont engage the motor. I have alot of car and small engine experience, but little with these old wet clutch's. Have put everything together according to the yamaha service manual for the bike and still wont disengage. The basket cover of the clutch separates from the plates, but have not been able to see if they separate when running. Basket does have some marks from plates, but nothing major and sanded down and small ledges it did have. Have two bikes, may swap this top end onto the other bottom end, but would like to figure this out. Any help would be greatly appreciated

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You're certain it's not your gearbox?

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I would check the gearbox shifter forks for wear, or even the drum shifter for wear plus the mechanism at the end of the gear shaft. Means you have to take it apart but on an old bike things do wear and if the box has been abused then thats your problem. Wheelies and some race bikes take a real tole on the gearbox. Just a suggestion but best I can come up with without seeing it. Try looking at this for an idea on the workings of the box.

 

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NICE animation!

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16 hours ago, Jc390 said:

I have a 1974 TX500A as the title says, and the clutch wont disengage. It happened while riding a few years ago. Shifted to first at a light with the lever pulled and it stalled. Ever since that day the clutch wont disengage the tranny. Have inspected the plates and measured everything seems to be in spec. The basket moves upon pulling the lever, however when its adjusted to allow that to happen, the kick start wont engage the motor. I have alot of car and small engine experience, but little with these old wet clutch's. Have put everything together according to the yamaha service manual for the bike and still wont disengage. The basket cover of the clutch separates from the plates, but have not been able to see if they separate when running. Basket does have some marks from plates, but nothing major and sanded down and small ledges it did have. Have two bikes, may swap this top end onto the other bottom end, but would like to figure this out. Any help would be greatly appreciated

So if you take the plain and friction plates out of the clutch does the inner and outer basket move ok, the outer should move with the crank, the inner should spin freely in neutral and you should be able to drive it turning the rear wheel at different speeds depending on gear.

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On 4/9/2021 at 4:59 AM, slice said:

I would check the gearbox shifter forks for wear, or even the drum shifter for wear plus the mechanism at the end of the gear shaft. Means you have to take it apart but on an old bike things do wear and if the box has been abused then thats your problem. Wheelies and some race bikes take a real tole on the gearbox. Just a suggestion but best I can come up with without seeing it. Try looking at this for an idea on the workings of the box.

 

Thanks for the animation! I do believe it must be in the gear set. Just not sure what as it moves thru the gears fine, can find all the gears no problem, clutch just wont disengage. Plan on taking tearing into it more today or tomorrow. Just gotta find myself a good pair of snap ring pliers first

23 hours ago, Cynic said:

So if you take the plain and friction plates out of the clutch does the inner and outer basket move ok, the outer should move with the crank, the inner should spin freely in neutral and you should be able to drive it turning the rear wheel at different speeds depending on gear.

The inner basket moves free for half a turn or so and then stops. The outer basket does turn with the motor. However, with the clutch installed and the lever pulled, it still does not disengage.

Ill try to take some pics and post them. Having a hard time finding someone locally to help so hoping yall might be able to point me in the right direction. 

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Half a turn and stops? So what happens if you put it in gear and turn the rear wheel. With the clutch fully stripped as that centre should spin freely in neutral. 

Also, i dont get how messing with the clutch affects the kick start, the crank and clutch basket are constant mesh, the kickstart drives the outer ring of the basket. You could take the clutch pressure plate, friction and steel plates out entirely and she would still start on the kicker.

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2 hours ago, Cynic said:

 

Also, i dont get how messing with the clutch affects the kick start, the crank and clutch basket are constant mesh, the kickstart drives the outer ring of the basket. You could take the clutch pressure plate, friction and steel plates out entirely and she would still start on the kicker.

If its like the xs400/250 you need the clutch engaged to turn the engine over. If I pull in the clutch I get no drive to the engine

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2 hours ago, drewpy said:

If its like the xs400/250 you need the clutch engaged to turn the engine over. If I pull in the clutch I get no drive to the engine

Ah so the starter runs through the gearbox. Schematics were a bit vague. Showed the kicker and the starter separately. 

Could be starter related then? 

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8 hours ago, Cynic said:

Ah so the starter runs through the gearbox. Schematics were a bit vague. Showed the kicker and the starter separately. 

Could be starter related then? 

not seen the schematics only what yam did to the 250/400

on them, the starter uses a chain to the crank.

 

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I cannot find tx500 stuff, but its apparently pretty much early xs500 so i was looking at the 75 xs500 which looks to have the same kickstart mech as most yams running on the clutch basket ring gear. Cannot find anything to confirm that though, could be a longer shaft running on one of the gearbox idlers maybe but that seems a lot of hassle

The starter motor runs a chain to a starter clutch that turns the crank, looks identical to my vmax.

Spent far too long wondering about it now. 

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  • 3 weeks later...

Some old motors  use first gear to kickstart, the  kick mechanism is inside the cases, [ H2,  & gt Susi"s same]  if you pull the cluch,= no kickstart engauges,  [ you have to find neutral if stalled,  So   his clutch is dissenguaging ,  as he said no kicker with clutch pulled in ,  i think  he has clutch drag, ..

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