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1975 XS500
- Thread starter bbailey72
- Start date
I think that's a good idea... but...
Find out what the torque is on the rotor nut, then use a torque wrench to turn it. That way you won't risk sheering off the end of the crank or stripping the nut.
Right now you don't know if there's damage preventing movement or just a bit of rust in the cylinders... or whatever. If you don't exceed the nuts rated torque, you'll lessen the chance of causing further damage.
Bob Wegman
XS650 Addict
You could pull the valve cover and check if there is a stuck valve in the partial open position, This is a four valve per cylinder engine. One rocker operates both intake valves, and a second rocker arm operates both exhaust valves. If a valve is stuck open there will be more clearance on that valve than its neighbor.
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Maybe ( Low ) pressure compressed air in via the spark plug hole.
if air is available I suppose a hand pump can do it ... Some rubber as gasket and try to pump in pressure
Notice differences Left Right and listening if leaking at valves
if air is available I suppose a hand pump can do it ... Some rubber as gasket and try to pump in pressure
Notice differences Left Right and listening if leaking at valves
GAAAAAZ
XS650 New Member
(google translation, I'm french)
Personally, I think it's a mistake to try and force a seized engine to turn over. There's more risk of breaking something than benefit. And in any case, it will have to be opened up to investigate and repair or replace whatever was blocking it. Perhaps the pistons will need to be changed and the cylinders rebored. So the engine has to be removed from the frame and opened up. There's no other solution in my opinion. On the TX500/XS500B, you can't remove the cylinder head with the engine still in the frame.
Personally, I think it's a mistake to try and force a seized engine to turn over. There's more risk of breaking something than benefit. And in any case, it will have to be opened up to investigate and repair or replace whatever was blocking it. Perhaps the pistons will need to be changed and the cylinders rebored. So the engine has to be removed from the frame and opened up. There's no other solution in my opinion. On the TX500/XS500B, you can't remove the cylinder head with the engine still in the frame.
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Upload the video to Youtube then click on the filmstrip button in the comment you want to add it to. Paste the Youtube link there.
Good wishes on your make it run journey!
I believe that engine also has a counterbalance mechanism. You picked something more complex than an XS650 for sure. I don’t know the XS500, but I believe that chain is driving the counterbalancer. Don’t allow it to get out of sync. It will probably have interference. 
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As per above, here's a view of the crankshaft and counterbalance shaft.
Bob Wegman
XS650 Addict
Keep the counterbalanced chain adjusted properly. Replace as needed. I remember some of these wearing out the sprocket on the crankshaft which wasn't replaceable.
That's not the counterbalance chain and gears your looking at in the OP's pic, It goes from the rotors gear to the starter, with an idler gear in 'tween. Looks like maybe an 8 or 10 to 1 gear ratio. Can't balance nothin' with that.
The counterbalance shafts on any balanced engine run at a 1 to 1 or 2 to 1 ratio. Looking at IBALT's IPC pic... the gears are all the same size... 1 to 1.
The balance shafts, gears and chain are another layer inside the engine... beneath the rotor.
There's actually two sets of chains and gears. One for the starter (left) and one for the balance shaft's.
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Uber complicated engine for 1973. Makes you wonder why they just didn't build a 3 or 4 cylinder with inherently better balance.
Oh wait, they did finally figure that out!
Oh wait, they did finally figure that out!
And nowadays nearly all twins (and singles) use a balance shaft setup of some sort to make them almost as smooth as a 4.
Perhaps they were ahead of their time?
Could very well be the case. The real turd in the punch bowl was the TX750 and I think the 500 just got painted with the same brush a little bit.
Oh, that and the cracking cylinder heads ...
Oh, that and the cracking cylinder heads ...
Oh, that and the cracking cylinder heads ...
Pretty good rundown on the two...
https://global.yamaha-motor.com/stories/yamaha-handling/list/vol03/02.html
Impressive work gentlemen ...
Is the stuck valve the first assumption ?
It appears to rotate the crank
Then I decided to put a little pressure on the kick starter just to see what would happen. Turns out, it sprays Mystery Oil all over the garage.
Is the stuck valve the first assumption ?
It appears to rotate the crank
Then I decided to put a little pressure on the kick starter just to see what would happen. Turns out, it sprays Mystery Oil all over the garage.
Saw that XJ400D in that article, very cool, didn't even know it existed (I guess not in the US...) Apparently rumors they are bringing a new one.
Dammit now I want both of those...
