Cosmo XS500

[cosmo]

By the way, do i get the cylinders off without splitting the chain? Wouldnt it be just a little more work to refit new rings while at it?

[JimR]

Originally Posted by cosmo

By the way, do i get the cylinders off without splitting the chain? Wouldnt it be just a little more work to refit new rings while at it?

Once you have the head off you just drop the chain down the cam chain tunnel, but remember to tie some string/wire around it so you can retrieve it, the cylinders will then come off .. no problem (but remember to put some rag under the cylinders just in case you have a broken ring). You can then do your top end rebuild no problem. But as the XS500 has to be removed from the frame to work on I would think it would be a good idea to inspect and/or repair the whole motor while the motor is out of the frame

[cosmo]

New question for you. I have been checking valve clearance, all alignment marks, both sides, im going to check the carbs and start it up before i pull it out of the frame for a valve job. want to make shure that it actally gets petrol on both cylinders. What i found today was that the rotorwheel on the left side had taken three quarters of a turn on the shaft from where it should be, does that affect the ignition timing in any way? And if i wanted to replace the carbs, is there a mikuni type fitted on some other model bike that could been used instead. maybe one without diaphragms.?

[JimR]

Originally Posted by cosmo

New question for you. I have been checking valve clearance, all alignment marks, both sides, im going to check the carbs and start it up before i pull it out of the frame for a valve job. want to make shure that it actally gets petrol on both cylinders. What i found today was that the rotorwheel on the left side had taken three quarters of a turn on the shaft from where it should be, does that affect the ignition timing in any way? And if i wanted to replace the carbs, is there a mikuni type fitted on some other model bike that could been used instead. maybe one without diaphragms.?

Carbs .... stick with the original ... going to slide type will cause you problems !
when you say rotor wheel I guess you are turning the crankshaft via the nut on the end of the rotor ... if so and the cams are not moving ... do NOT try to start the bike .. just pull the motor out and at least pull the top end to bits to work out why you have that problem

[cosmo]

I mean the rotor on the left side, it has moved approx 270 degrees because of a deformed woodruff key. will that affect the power to the coils in any way? Is it imperativ that the rotor is on the woodruff mark in order to produce power in the right moment or has it no impact as long as the rotor is spinning. I guess it has been stuck in this position for years and i was hoping that this was the reason for the bike never running right.

[JimR]

Originally Posted by cosmo

I mean the rotor on the left side, it has moved approx 270 degrees because of a deformed woodruff key. will that affect the power to the coils in any way? Is it imperativ that the rotor is on the woodruff mark in order to produce power in the right moment or has it no impact as long as the rotor is spinning. I guess it has been stuck in this position for years and i was hoping that this was the reason for the bike never running right.

Yes the key needs to be in place or else the charge to the battery & ignition will be flawed ... replace the key !

[cosmo]

The bike starts very easily and it gets hot on both cylinders and is idling fine, expect it to get even better when synced carbs. BUT, it has the same problem it started out with all those years ago, when you rev it up it stays up there before it slowly decends to idle again, is that the spings on the ignition mecanism that is too weak to pull it back from advanced ignition or is it some carb problem. So far, so good!!

[JimR]

Originally Posted by cosmo

The bike starts very easily and it gets hot on both cylinders and is idling fine, expect it to get even better when synced carbs. BUT, it has the same problem it started out with all those years ago, when you rev it up it stays up there before it slowly decends to idle again, is that the spings on the ignition mecanism that is too weak to pull it back from advanced ignition or is it some carb problem. So far, so good!!

That is either carbs or an air leak in the induction system (this does include the intake valves)

[cosmo]

Ordered a brand new ignition timing governor on ebay for 69$. This because the old one has some vear and not original springs. I recall that vhen we tried to make some springs and they were too hard it wouldnt rev up. The carbs are dismantled and soaked in deb altrans acidic cleaner solvent and cleaned with compressed air. Are going to polish some of the covers to freschen it up visually too.

[JimR]

Originally Posted by cosmo

Ordered a brand new ignition timing governor on ebay for 69$. This because the old one has some vear and not original springs. I recall that vhen we tried to make some springs and they were too hard it wouldnt rev up. The carbs are dismantled and soaked in deb altrans acidic cleaner solvent and cleaned with compressed air. Are going to polish some of the covers to freschen it up visually too.

Sounds good ! ... post how you get on