GS850 Head gasket

[brendanGS850]

Hi,
I am using the winter to get my 79 GS850 running right, starting with a valve adjustment. WHile I'm doing this I'd like to fix as much as possible since riding season is a good 3 months away.

I had previously replaced the valve cover gasket hoping to fix an oil leak. It did fix it partly, but with the valve cover no longer leaking now I can see that the headgasket also appears to be leaking oil.

Are there any writeups on this? I have never pulled a head from a bike before.

ALso anything else I should get while I'm in there?

Thanks in advance.

 

[Nessism]

Sorry to be grumpy but this topic is quite common and has been covered extensively in older threads. A search of the archives will turn up all kinds of pertinent information.

Basically, when pulling the head both the valve stem seals and base gasket should be replaced as well. Many people also choose to install new rings at the same time.

Good luck

 

[brendanGS850]

Ok... perhaps I am not searching in the right place, but I did search this forum before posting:

http://www.thegsresources.com/_forum/search.php?searchid=2456621

I also read through BassCliff's material. And did not see anything that actually explained a head gasket replacement.

Sorry that I have not been on this forum for years, but for someone new to this I don't think it is all that easy to find.

 

[BassCliff]

Hi,

The only thing tricky about head gasket replacement is timing the valves. This procedure is in the manual. There's a guide on Mr. bwringer's site that explains TDC. I'm planning to refresh the top end of my bike sometime later in the spring. This will include new valve seals, new rings, honing the cylinders, base gasket, head gasket, associated O-rings and seals, service the cam chain tensioner, etc. I will do my best to write up the procedure but it is outlined in the manual.

Could your leak be from the tach cable send gear (seals) in the head? This repair is also outlined on Mr. bringer's site.


Thank you for your indulgence,

BassCliff

 

[JEEPRUSTY]

Yes well
I would think that users doing write ups would be able to tag them,
But they can't

 

[cowboyup3371]

Is it possible that it is residue from your valve cover? I would clean everything very well first, put something on it to help capture the leak, and then keep an eye on it for a bit. Might be cheaper and easier than tearing it all down before it needs it.

 

[koolaid_kid]

Brendan, I'll stick my two cents in here:
Most recommend replacing the base gasket when you replace the head gasket. They state that it will start to leak if you do not. (I've never had the experience, but I have read the posts.)
This means removing the cylinder block. It is not impossible, but it is a decent amount of work.
So I would do everything in my power to make sure it is not something easier to tackle.

 

[brendanGS850]

Thanks for the responses. The leak is definitely not coming from the valve cover gasket as I had cleaned the whole engine after I replaced it and the oil appeared again. I'm also fairly certain it's not coming from the tach cable because there doesn't seem to be oil on any of the fins above the head gasket.

That said I really didn't want to tear down the whole engine... what are odds that torquing the head bolts to spec would solve it?

The bike does have almost 40K on it

 

[koolaid_kid]

I would certainly try it, but I would start studying. You are not tearing the engine down. Once you remove the head, you then lift the cylinder block off, exposing the pistons and rods. Since you are in that deep, you will want to clean the piston tops and measure the rings to make sure they are in tolerance. You should be able to do this with the engine still mounted in the frame, but the frame will be a hindrance at times.
You will need a top end gasket and o-ring set, plus exhaust gaskets. It is also a good time to check the intake o-rings. Pretty much everything BassCliff listed is what you want to do also.

 

[DanTheMan]

I replaced the head gasket on my 850 when it had 52000 or 55,000 miles on it (can't remember for sure). It blew out and dumped oil all over my left leg. The only reason that happened was because I got stuck in construction traffic in Las Vegas, NV, at 110 deg F. I couldn't keep shutting down and restarting either, so some of the run time it got real warm, and was "pinging" on acceleration due to the heat. The head gasket lasted for another 3,000 miles beyond that incident and popped 3 weeks before I had to teach an Experienced Rider Course, so it was a quick job. I didn't do the base gasket or the valve seals then. Now the valve seals are so hard they don't seal anymore and I'm sucking oil down through them, but look at the miles I've got on the 850 (it's in my sig).

 

[Brownie]

Having trouble with the head gasket on my 1979 gs850 not leaking, what is the correct gasket for this bike and any stop leak tips would be great. my mechanic has milled the head and is still getting leak , he states there may have been some discrepancy with the bike parts from gaskets regarding previous to '83 and older bikes and '84 and younger. Thanks for the input and sorry couldn't find this else where.