Cylinder O rings

[moizeau]

Just about to put the liners back in and noticed a groove, then remembered that I took an O ring out of each cylinder. It must seal the cylinder to the liner. Mine were FT having to get them to 200 degs to get them out without a press.
Are they really needed and if so has anyone got any sizes please? I can't imagine there's a Kwak part no. 'cause you not supposed to go this deep.
That scuppered this evenings adventure.
Thanks in advance

[z1bman]

http://www.z-power.co.uk/oring-cylinder ... 01000-73mm

[moizeau]

Thanks for the link but that's not the one. At 73mm they're way too small. The O ring I'm after goes between the ally bore of the cylinder and the liner and would be around 79mm. Unless I've really missed something, which is very possible.

[zed1015]

Those are the correct ones.
They stretch for a snug fit over the liner.

[moizeau]

This one, that's recessed into the ally cylinder prior to easing the steel liner in?

IMG_3496.JPG (117.15 KiB) Viewed 3119 times

[zed1015]

This one, that's recessed into the ally cylinder prior to easing the steel liner in?
IMG_3496.JPG

Yes!
It goes on after the liner is in though.
Roll it over the liner spigot and into the groove.
A wipe of oil will make it go in the groove easier and small flat bladed screwdriver or similar to get it close to flush with the surface.

[z1bman]

what bike is it for ? i have only seen that type that fit inside the cavity on water cooled engines

[moizeau]

Cheers Rob, it's my GPz11 Uni

[Al]

There is a tiny counterbore clearance at the bottom of the barrels where the spigots emerge. It is less than 1mm or so wide. You wouldnt get an 'O' ring in it. Those 'O' rings are usually on the 900 / 1000 kickstart motors and people say they do nothing useful. I have not seen any on 1000J or 1100J style barrels inc. 1100 Unitrak. If i had any concerns about that gap i would seal it with high tek / high temp silicone sealer but have not done and had no problems so far. They dont seem to suffer with drawing oil up past the liners as far as i have seen to date.
AL

[z1bman]

there was a service bulletin about oil creeping up the liners & kawasaki recommended coating the liner with 3 bond before inserting them into to cylinder

[moizeau]

Thanks very much chaps. There's not enough clearance to coax an O ring in once the liner is in place so it would have to go in before the liner.
The groove starts 3mm up the cylinder, is 2mm deep and 3mm wide. Difficult to measure a used O ring, but they seem to be 79mm x 2.5~3mm.
I've found a local supplier that does 79x3 for £1.60 each in FKM80 which is good to 200 degs, (NBR70 is only good up to 100) so will probably get some of those, see if the liners go in with them in place or just mangle them? If mangled, drop the liners and go without. Maybe the groove is a left over from when the liners were honed out of the cylinders or as a fail safe? There doesn't seem to be any evidence on the ally of oil creepage and the liners were a really tight fit (I needed 200 degs to get them out without a press), so quite likely Al is spot on and they're not needed.
Thanks again, any further opinions most welcome.

[Al]

If you can get suitable alternative 'O' rings that fit i would put them in. It cant do any harm and may off-set a potential future problem. If they are in there than there is likely a reason. The 900 / 1000 versions which were mentioned; i think, sit passively on the protruding liner spigotts rather than in a machined rebate but i could be wrong.
AL

[moizeau]

Yep, I'm going with that Al, just see if they can supply during the French shutdown