cylinder base gasket 73' 850

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Feb 4, 2008
I can't find a cylinder base gasket for my 850. Does only the 750 and
850 75'up have one? I can mount it bare with silicone or with a selfmade gasket. I have a lot of gasket paper in space, i think a 0.5mm would be fine.
Thanks for any informations
Only the Mk1 850 didn't use the base gasket. I believe it was re-introduced because some owners were blocking up the oil return holes with gasket gue. You could make one, buy one they cost pennies, or leave it out, if you leave it out the compression gets near 9:1, ensure you check the oil way is clear before the head goes on.

Thanks, thats fine. I'll run it without the gasket.

Sorry about my questions, the hole bike was stripped down when i bought it. It's my first norton at all, so a lot uf ugly questions are growing up... :D

I use silicon gasket here but to be sure you have no blockage insert a piece of electrical cable down the barrel oil drain and into the case opening. Just take care when you lower the barrel that the cable is not trapped or any insulation gets shaved off and into system. Leave it there for a few minutes until the sealant cures. Make sure the cable is not a very tight fit or you might have trouble getting it out especially if the barrel and case holes are not in 100% alignment.
I highly recommend you resist the urge to use silicone here. This application begs the use of anaerobic sealer such as Loctite 518. If you insist on using silicone, make doubly sure none can squeeze out on the inside of the case or into the oil drain hole.

Cylinder base gaskets can give a lot of trouble on a 750 and I never use them there. An 850 with the thru bolts seems to stay tight with a gasket, but as Cash points out, they aren't necessary.

By the way, a base gasket for a '75 would be the same as one for a '73-'74.
Another problem is, the oil gallery in the block is so close to cylinderbore in the block, that the wall thickness is less than 0.5mm ! I will make it thicker with aluminium filler, so i have more seal area around the oil bore.

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