Author Topic: YS63 leaking valves  (Read 256 times)

Offline Mike W

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YS63 leaking valves
« on: 14, July 2017, 05:47:40 PM »
I was wondering if anyone may be able to help.


My trusy YS63FZ-S  was down on power after quite a lot of running. I stripped the motor to install a new set of bearings and piston ring. While cleaning valves, particularly the exhaust, I've noticed the intake and exhaust valves leak.


I tried lapping the valves by cynoing a wooden dowl to the top of the valve and ran dowl between fingers while valve was in the cylinder head, using fine valve grinding paste also, gritty smokers toothpaste, well cleaned both the valves and valve seat.
But,  I can't achieve a totally leak free valve seat.


Does anyone have any experience in lapping valves? Or is it acceptable to have slight leaks.


Thanks Mike.

Offline Ashley Hoyland

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Re: YS63 leaking valves
« Reply #1 on: 14, July 2017, 07:05:50 PM »

Hello Mike


Sorry to hear you are having problems with your YS 63.


I have lapped valves by using course then fine grinding paste.  I put a tight fitting tube on the valve stem and pulled whist grinding, but no reason this should be any more successful than your method. 


It did take longer than I thought though.


Ashley

Offline Mike W

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Re: YS63 leaking valves
« Reply #2 on: 15, July 2017, 07:36:13 PM »
Hi Ashley,
Thanks for your reply, I've sorted the leaks. As you say, it takes more time than you think.
I acquired some lapping compound called 'Time Saver' available in different courses. I used the finest they do, mixed with thin oil.


After lapping, valves and cylinder head were ultrasonically cleaned with 'Gunk' engine degrease. YS now has very strong compression.


I made a tool to help remove the valve spring retainer clips. Always a difficult job in the past. Valve springs can be removed / installed in minutes.


Mike.

Offline Ashley Hoyland

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Re: YS63 leaking valves
« Reply #3 on: 15, July 2017, 09:07:53 PM »

Pleased you have had some success.


Ashley