Glazed bores?

[Greg65]

With time on my hands I’m taking the opportunity to investigate the high oil consumption on my Suzuki GS 1000.

So first up a bit of background information. The purchase was a bit of a spur of the moment, I really should have gone for a sorted GS 550 but a big shiny picture fooled me. If nothing else I have learnt a lot about spannering. The first problem I encountered was the bike was running very rich, you only need your nose to tell that. The standard air box had been removed and cheap foam pods added and the carburettors rejetted. I stripped them and found two bodies had broken pilot screws (the sharp tapered one) wedged in the body. In addition the main jets had been increased 10 steps above standard, way in excess of a pod requirement. So two replacement bodies sorted, all then ultrasonic cleaned and smaller mains put in and proceed to road test and change mains again settling on 3 steps up.

So about 2,000 miles later oil consumption high, no obvious leaks but brown/black staining around exhaust I start to suspect the valve stem seals. So commence top end rebuild not knowing the history, as I strip I am finding a number of new parts, cam chain, guides and healthy looking stem seals. Piston crowns and head are heavily coked, not soft, I think a combination of oil and unburnt fuel.

So here’s some pictures.

So am I suffering from bore glaze due a poorly run in engine? What do I need to check? Will a simple hone cure the issue or will I require new rings as well?

Many thanks for all advice.

Greg

[royhall]

Do you by any chance have the GS knock. A tapping sound at tickover to low revs that is apparently camshaft end float. I'm told they all do it over 40k miles but I don't believe them. Supposed to be all the GS models right down to the 400 twin.

Bit hard to tell from a photo but those bores definitely don't look glazed to me. Check the valve guides aren't shot as the early engines had an off centre valve that allegedly causes the cam end float and guide wear. The offset valve (design error) puts an end on force on the cam.

[taysidedragon]

Those valve seats look poor to me.

[Greg65]

Hi Roy, no tapping so far. Yes the valves are not seating well on 3 of them, all will be addressed. I need to visit an engineer with better measuring equipment than I possess. This is the frustrating part of being locked down at home, time rich access poor.

[Bryanj]

As a diferent bike I do know that the Kawa Z 1000 when they first cam out were being rebored under warantee due to buyers running in to carefully glazing bores and rings. Just honing and new rings would not cure them

[Greg65]

Thanks Bryan, I’ll do some more research and post on an American forum which usually has some good advice. I need to get the bores measured and form a plan