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1981 gs850gl low compression

  • Thread starter Thread starter herb
  • Start date Start date
H

herb

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Trying to finish my winter project and wondering if I was sent the right head gasket. Does anyone know if there was an update on these as my old one was the standard paper style head gasket and the new one is all metal. The problem I'm having is this new gasket completely covers the square o-ring that fits in the groove around the cam chain and it is allowing compression to leak into the crankcase past the seal and head gasket. The old head gasket just surrounded that o-ring but did not go over top of it. Am I supposed to just throw that o-ring away or did cyclepartsnation send me the wrong part. I ordered part #11141-49410 that was then replaced by #11141-49002. Any help would be appreciated.
 
With the MLS head gasket I don't think you are suposed to use a tunnel O-ring. Did you use both?
 
Yes I did and if thats the problem I'll just throw that o-ring away. I didn't have the old head gasket handy when I was putting the new one on and didn't realize the difference until after I had pulled it all back apart and tried to figure out what was wrong for an evening.
 
Last edited:
As Nessism said the new MLS gasket covers the rectangular slot for the cam chain rubber gasket and does away with that gasket.

Just for info did your gasket come covered with any compound on the outside?
 
Their was a lengthly discussion & research done a while back. As said just leave the O ring out
 
Ya, I figured if that was the deal it had been covered somewhere, but I couldn't find it anywhere in the forums. Also, the head gasket did not come with any type of compound on it. It was a just a plain steel gasket. Let me guess, there's something else about this whole deal I know nothing about
 
Herb,
You may want to read up a bit on MLS gaskets if you want. I think Cometic has something on them. I have only used the aftermarket MLS gasket which had a thin Viton layer on the outer surfaces.
What I understood is that MLS gaskets are the norm for the present day vehicles as they are more durable and allow for closer tolerances. The one requirement is that the mating surfaces are of a high quality and have a near polished finish. Aftermarket MLS gaskets for older vehicles have a thicker layer of sealing compound on the outside to allow for scratches and microscopic blemishes that would not have been a problem with the older type headgaskets.
I have seen an MLS taken out of a GS1000 with a layer similar to silver paint on the outer parts, but I am not familiar with a bare metal to metal finish.

I think Rapidray, one of the forum members, uses MLS head gaskets and maybe you could ask him.
 
Thanks for all the info everyone. Now I just need the time to put it back together. Darn day job
 
I was just searching the forums because I just purchased a head gasket off ebay because I think I may have a compression leak somewhere. How big of a project is it taking the head off of a 79 gs850 to put the gasket on? How long did it take you and did you have to pull the motor off or not?
 
Changing the head gasket can turn into one of those "snowball" projects. :eek:

Bumping things enough to get the head loose will usally disturb the base gasket, so you had better figure on replacing the base gasket, too.

Of course, you have to remove the cylinders to change the base gasket. Since the cylinders are off, check the rings. How many miles on the engine? You might want to change the rings, too.

If you replace the rings, you will want to hone the cylinders.

Whether you do the base gasket or not, the head is definitely off. Since the head is off and you likely got new seals with your gasket kit, you may as well replace the valve seals.

Don't forget to check the cam chain for proper length before you button everything back up, too.

Time:
To remove the head, maybe 15-20 minutes. Another 10-15 minutes will have the cylinders off, too. Depending on how the previous gaskets were installed, you may have clean mating surfaces or you may have to do some scraping. Figure about an hour for putting things back together, then a bit more for re-checking things, including valve adjustment. Overall, 4-6 hours, depending on how much gasket scraping you have to do. Best part is that it can all be done with the engine in the bike.

.
 
Also figure some time to deal with the exhaust bolts. . Usually at least one will break/ twist off
I would plan on a long weekend.
 
syren said:
I was just searching the forums because I just purchased a head gasket off ebay because I think I may have a compression leak somewhere. How big of a project is it taking the head off of a 79 gs850 to put the gasket on? How long did it take you and did you have to pull the motor off or not?
Click to expand...

Mine has turned into a multi-week project I'm sure now because I discovered my low compression was due to crank issues. I saw your earlier thread and it piqued my interest before I found my source (and before I was allowed to post). Did you ever run a real compression test?

I do think I got the head gasket off without disturbing the cylinder gasket. That has since been ruined by pulling the whole block out. But you know of course that you'll need at least a valve cover gasket in addition to the head gasket, right?

Anyway, I think I'd want to see some wet/dry numbers for each cylinder before pulling the head off.
 
I do have a valve cover and a head gaskets on the way. I'm not sure what you mean by wet and dry numbers but I am getting about 60psi according to the compression tester. I tried all four cylinders and they are all getting roughly the same. I also have fuel problems but I think I will be able to get those taken care of. I have an oil leak some where as well so I think I am going to have to take the head and valve covers off regardless. Going to be cleaning carbs and replacing fuel line and looking at tank and petcock this weekend.
 
syren said:
I'm not sure what you mean by wet and dry numbers but I am getting about 60psi according to the compression tester.
Click to expand...

Did you hold the throttle open?
60 is about what they read with the throttles closed.
 
tkent02 said:
Did you hold the throttle open?
60 is about what they read with the throttles closed.
Click to expand...

No, I didn't. I didn't know I had to. Doh! I dont hold the throttle open when I am trying to start it though do i?
 
syren said:
Doh! I dont hold the throttle open when I am trying to start it though do i?
Click to expand...
No, you shouldn't hold the throttle when starting the bike.

BUT ... you are not trying to start the bike, you are trying to get compression numbers. :eek:
The correct procedure for getting compression numbers is to hold the throttle wide open. Ideally, the engine should be at operating temperature and all spark plugs removed.

The difference between "wet" and "dry" readings refers to doing the test "dry" first. Just hook up the gauge and get some numbers. If they are low, add a teaspoon or so of oil to the cylinder, then try it again "wet". If the rings are bad, the oil will help seal the rings and the compression numbers will rise. If they don't rise much, your problem is likely with the valves.

.
 
Steve said:
Changing the head gasket can turn into one of those "snowball" projects. :eek:

Bumping things enough to get the head loose will usally disturb the base gasket, so you had better figure on replacing the base gasket, too.

Of course, you have to remove the cylinders to change the base gasket. Since the cylinders are off, check the rings. How many miles on the engine? You might want to change the rings, too.

If you replace the rings, you will want to hone the cylinders.

Whether you do the base gasket or not, the head is definitely off. Since the head is off and you likely got new seals with your gasket kit, you may as well replace the valve seals.

Don't forget to check the cam chain for proper length before you button everything back up, too.

Time:
To remove the head, maybe 15-20 minutes. Another 10-15 minutes will have the cylinders off, too. Depending on how the previous gaskets were installed, you may have clean mating surfaces or you may have to do some scraping. Figure about an hour for putting things back together, then a bit more for re-checking things, including valve adjustment. Overall, 4-6 hours, depending on how much gasket scraping you have to do. Best part is that it can all be done with the engine in the bike.

.
Click to expand...
You forgot about splitting the cases to install the new cam chain. Then replacing crank seals, ......, and on and on..... Good list though!
 
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