GS850 engine strip

[Matt Lund]

Hi due to a plug hole needing a helicoil repair i have to remove the head from my 80 GS850. After finding silicone sealant around the head gasket i have decided to strip the whole engine and get the cases vapour blasted. I have not removrd the head yet but turning the engine with the hexagon on the timing pickup side i can hear a hissing from within the crankcase which sounds like blow-by. Is this a sign of worn piston rings? The camshafts havr no scoring at all so i reckon the engine is not very worn at less than 50000 miles but due to the bodges i have found and the neglect the bike has suffered stripping will give me piece of mind. Is there anywhere in the UK i can get standard or oversize pistons and rings if it does need them replacing. Thanks, Matt

[SqDancerLynn1]

That is a normal noise !! Your motor probably only needs a top end rebuild. Not a complete overhaul.
Plug threads can be repaired without removing the head !

[tkent02]

That is a normal noise !! Your motor probably only needs a top end rebuild. Not a complete overhaul.
Plug threads can be repaired without removing the head !

With only 50,000 miles it probably just needs new gaskets and seals.

[850 Combat]

Go to the auto parts store and put an insert in. Ride it and see if anything is wrong. I wouldn't worry about silicone.

[tkent02]

Go to the auto parts store and put an insert in. Ride it and see if anything is wrong. I wouldn't worry about silicone.

+1, even if you do decide to tear it all apart, running it first is a good idea. I'd hate to split the cases, put it back together and then find a transmission problem a test ride would have easily found. Also get it running correctly so you know the carburetors are right before trying to break the engine in. If the jetting is wrong it won't break in very well.

Myself, I'd just ride it.

[barnbiketom]

+1 just insert repair the one plug. vacuum out with a vacuum and a small hose.

ride it.

[Matt Lund]

Thanks. It ran but badly and no scary noises but i dont trust what maintenance the bike had had. There is grit in the oil filter chamber and a layer of black sediment in the primary drive cover. I know oil filter changes have been missed as i was told so and it had a Motad 4-1 exhaust which must be removed to get to the filter and the exhaust was so rotten it fell apart when i removed it so that's not been off in a long time. Filter is filthy too. The silicone around the head gasket is worrying because the person who puts that on a head gasket is liable to accidentally drop something into the cases so that head has been off before and the cams had been churning up the mounds of silicone on the cambox gasket. Someone has been at that engine and i don't trust their working practises so i'd better take a look inside just to be safe.