gs850 oil in exhaust, top end rebuild ideas, possible causes

[Guest]

Hello all,

Finally got my 850 up and running again. Problem is, while I was adjusting the carb synch I noticed a puddle of oil under the #3 and 4 muffler....... random "WHITE" puffs of smoke and no black/blue smoke

The bike has 30K miles on it, i have not taken the head off to find out what the problem is yet.

I plan on replacing the head cover and head gasket with a real gasket

I also plan on getting new valve seals, maybe guides?


I suppose what I am going to ask is; beyond a seal failure what else could have happened?

Maybe I filled the engine with too much oil during the oil change?

Just looking for thoughts, I realize that I have not properly diagnosed the engine yer

[matt1100]

I think you already got it, mine leaked form the #4 flange prior to putting new valve seals in. probably all it needs. From what I gather here (and my little experience) guides are seldom a problem on these machines. Ohh, and be careful pushing them on too far during install or you'll be waiting for more, hard lesson I learned there.

[blackstag]

I am finally getting around to addressing this issue. I have purchased all the appropriate gaskets and such to get the job done.

However; during the teardown today i went ahead and did a check of the valve clearance.

Not one of the valves could allow for a .002in clearance (.05mm) am I doing something wrong here?

the engine has 30K miles on it and has probably never had its valves adjusted........ I think I may be buying me some shims

[Dogma]

With 30k on it, the valves could definitely all be tight. It's certainly not unheard of. Continue with the tear down and begin inspecting everything. See if the valves and seats are burned, see if the guides are too loose, etc. I've heard opinions from 3 different machinists (2 specializing in bikes, one of which was the crank builder Pearson) that the book values for guide clearance are unnecessarily tight.

If you don't have a thin enough shim, go ahead and get the thinnest one you can ordered (2.35, I think). Before reassembling everything check the clearances again with the thin shim. It's super easy while the head is off and the springs are out, if you're taking the head off to change the valve seals. Steve's spreadsheet (find instructions in his signature for instructions on how to get it if you haven't already) will make it easy to do the math and keep track of what new shims you'll need and where they'll go. Get the new shims ordered and they may even arrive before you have things back together enough to install them.

[blackstag]

Thank you for the information sir. I will work my way through the process and see what I can do. To summarize, your saying that I should shoot for a larger clearance than stated? maybe shoot for .003 or more?

thanks!

[eil]

I find it simplest to work in metric units only when doing valve clearance adjustments. The best way to do that is to get real metric feelers like these:



Unfortunately, they can be hard to find locally. They are all over eBay, though. There is a trade-off between price and how quickly the package will be waiting on your front door.

The factory service manual specifies the clearances at between 0.03 mm and 0.08 mm inclusive*. Anything in this range is considered acceptable until the next service interval. If you try to get all of the clearances on all of the valves exactly the same, you will be replacing almost all of the shims which won't be cheap.

* But folks here often go as high as 0.10 mm and there have never been any reports of issues.