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'79 GS1000 head gasket replacement

  • Thread starter Thread starter sdbuchert
  • Start date Start date
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sdbuchert

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About 2000miles/1.5 years ago, I had my GS1000's top-end apart for inspection. I put it back together with a non-Suzuki head gasket, and of course it leaks. I bought a new Suzuki head gasket for this time around, and I am wondering if I need to replace the base gasket between the cylinder block and the crank case at the same time I replace the head gasket. The base gasket was replaced with the head gasket when I had the top-end apart last time. Anyone successfully (leak free) replaced a head gasket without replacing the base gasket too? I feel like I should just replace the base gasket at the same time so as not to chance wasting a new...and expensive...head gasket. Thanks for your comments.
 
I changed my head gasket out without changing the base gasket, BUT, if you prize up the bores, you will HAVE to change it.
 
As usual....it depends. If your cylinders have become 'stuck' to the base gasket/ crankcase and you didn't have to tap the head off (i.e. it just lifted off cleanly) there's a stong probability that the base gasket will be ok. I've done this a few times successfully, but bear in mind this is on UK bikes that have been dosed in salt for years and only because the cylinders can be right b*stards to get off.
If your cylinders are easy to pull, or you have any doubts, I'd suggest changing. It's an easy enough job to do - as long as the cylinders haven't salt welded themselves on!
 
I wouldn't be worried about changing the base gasket.

It is generally recommended to replace the base gasket when pulling the head gasket because it has been in place 20+ years. The base gasket has then hardened up and can break when the head is removed.

After 2 years, the base gasket should be pretty pliable, and, if you greased it, it shouldn't stick to the barrels.

Also, The head should just pop off and not have to be hammered off. Less force on the base gasket.

So, replace the head gasket and be done with it
 
surely it is false economy? if you got your head off anyway, buy a top end gasket set and replace the base gasket at the same time.
why go through the grief/expense/ time of putting your head back on, cams in, timing it up, then putting all the rest of the bits back together then after a few miles finding your base gasket weeping oil! then having to strip it all out again and having to fit a new gasket.
doesn't make sense to me, if it was a clutch cover then yes i would risk it with a good clean up if the gasket came off ok and maybe a smear of hylomar but dont risk it with the top end of your engine.

just my opinion!
 
So then rehone the cylinders too?
I would any time the block comes off of the pistons.
My bike, if it didn't leak before, and if the cylinder remains stuck to the cases, I'd leave it alone.
If the cylinder does come loose, I'd replace the gasket, which requires removing the cylinder block. To me that would require honing the cylinder again, and and breaking the engine in once assembled, as if it was a complete rebuild. (run it hard)
 
What brand of head gasket failed, and what type of gasket was it - fiber composite, MLS, or ?.

I recently bought a gasket kit for my 1000 and went with Athena because they use a MLS head gasket that has a skim layer of viton rubber on top and bottom. Fingers crossed that the seal is going to be OK. Cost for the entire kit was $65 shipped vs. $70 for a Suzuki head gasket alone.
 
tkent02 said:
So then rehone the cylinders too?
I would any time the block comes off of the pistons.
My bike, if it didn't leak before, and if the cylinder remains stuck to the cases, I'd leave it alone.
If the cylinder does come loose, I'd replace the gasket, which requires removing the cylinder block. To me that would require honing the cylinder again, and and breaking the engine in once assembled, as if it was a complete rebuild. (run it hard)
Click to expand...
why do you need to hone the cylinders if you just take the block off to replace a gasket?
you may think the block remains stuck to the cases but you have released all the torque pressure squeezing it down and it is now in a precompressed state, a gasket seals by compressing between 2 surfaces and forming a leak tight seal. once a seal is broken you cannot guarantee it will seal again.

personally i wouldnt take the risk but others may do
 
Agemax said:
why do you need to hone the cylinders if you just take the block off to replace a gasket?
Click to expand...

Don't think there's much chance of getting the rings back in exactly as they were.

Agemax said:
you may think the block remains stuck to the cases but you have released all the torque pressure squeezing it down and it is now in a precompressed state, a gasket seals by compressing between 2 surfaces and forming a leak tight seal. once a seal is broken you cannot guarantee it will seal again.

personally i wouldnt take the risk but others may do
Click to expand...

Hasn't leaked on the few I've done this to, but it's only been a few. Again, if the block moves at all on the cases it's coming off.
 
Agemax said:
personally i wouldnt take the risk but others may do
Click to expand...

I'd agree - but sometimes if you've got an old flogger and the barrels have become welded on you can be in serious trouble trying to get them off. In that case I reckon it is worth the risk. (Avoids loads of cursing)

If sdbuchert did a top end rebuild only a few miles ago (and not 50k / 30 years ago) he won't be in that boat though.
 
Nessism said:
What brand of head gasket failed, and what type of gasket was it - fiber composite, MLS, or ?.

I recently bought a gasket kit for my 1000 and went with Athena because they use a MLS head gasket that has a skim layer of viton rubber on top and bottom. Fingers crossed that the seal is going to be OK. Cost for the entire kit was $65 shipped vs. $70 for a Suzuki head gasket alone.
Click to expand...


Nessism,
Im not sure what brand of gasket I used, but I will look and let you know.


I think I will probably replace the base gasket at the same time just to be safe, BUT........

As far as honing the cylinders... When I had the top end apart last time (head and cyclinder block off) to replace a weaping base gasket and fix 2 broken exhaust bolts from the previous owner, the bike had 18,000 miles on it and I didn't hone the cylinders. The bike runs great, doesn't burn any oil, and has great compression. Maybe I just got lucky? I'm wondering if its worth the cost of honing. How much $$$ is it? Thanks everyone for your insight.
 
I thought honing was only required when changing the rings, not each time the cylinder is removed. As long as the rings are not distrubed too much during R/R of the cylinder, I think you are safe to skip the honing.
 
Nessism said:
I thought honing was only required when changing the rings, not each time the cylinder is removed. As long as the rings are not distrubed too much during R/R of the cylinder, I think you are safe to skip the honing.
Click to expand...
correct, honing is not required when lifting the block just to replace a gasket, maybe worthwile if its a long time since the block was off and the bores look slightly worn, a new set of rings would not be a bad idea either if you want to be sure.
as long as the pistons look ok with no excessive scoring then everything should be ok
 
Nessism said:
I thought honing was only required when changing the rings, not each time the cylinder is removed. As long as the rings are not distrubed too much during R/R of the cylinder, I think you are safe to skip the honing.
Click to expand...

Agreed, at 18k there's no reason to hone the bores. Just make sure the ring ends are staggered on each piston before putting the barrel back on.
 
Big T said:
Agreed, at 18k there's no reason to hone the bores. Just make sure the ring ends are staggered on each piston before putting the barrel back on.
Click to expand...

I'd try to put the cylinder down with the rings in the same position as before...as long as the gaps are not in-line. I think you have the best chance to maintain the same cylinder seal as before that way.
 
Nessism said:
What brand of head gasket failed, and what type of gasket was it - fiber composite, MLS, or ?.

I recently bought a gasket kit for my 1000 and went with Athena because they use a MLS head gasket that has a skim layer of viton rubber on top and bottom. Fingers crossed that the seal is going to be OK. Cost for the entire kit was $65 shipped vs. $70 for a Suzuki head gasket alone.
Click to expand...

I must have bought the same kit. I looked in my shop, and the head gasket was from an Athena gasket set, and it was an MLS type. ...I had the same thinking on price... I did find a NOS Suzuki head gasket on ebay for $20 which i'm using this time around. I don't know, however, that the head gasket is to blame. When I put the top-end back together, the rubber o-ring (actually rectangular) that seals around where the cam chain comes through the block was a bit smaller than the groove it was supposed to fit in, and it kept popping out of the groove. It is possible that it may have popped out of the groove again as I set the head back on, and that could be my source of oil leakage. Other than the O-ring problem, I have been very happy with the gasket set.
 
sdbuchert said:
I must have bought the same kit. I looked in my shop, and the head gasket was from an Athena gasket set, and it was an MLS type. ...I had the same thinking on price... I did find a NOS Suzuki head gasket on ebay for $20 which i'm using this time around. I don't know, however, that the head gasket is to blame. When I put the top-end back together, the rubber o-ring (actually rectangular) that seals around where the cam chain comes through the block was a bit smaller than the groove it was supposed to fit in, and it kept popping out of the groove. It is possible that it may have popped out of the groove again as I set the head back on, and that could be my source of oil leakage. Other than the O-ring problem, I have been very happy with the gasket set.
Click to expand...


The Athena gasket kit that I have does not have the rectangular O-ring that goes around the cam chain cavity. The MLS type gasket is supposed to seal abound the channel all by itself. Have to admit, I'm a little concern...
 
Nessism said:
The Athena gasket kit that I have does not have the rectangular O-ring that goes around the cam chain cavity. The MLS type gasket is supposed to seal abound the channel all by itself. Have to admit, I'm a little concern...
Click to expand...

hmmm. Well, I could be wrong about the head gasket. It is out of an Athena kit that I bought about 2 years ago, and as I remember the gasket was layered steel. I don't know for sure, however, that it had viton rubber on it. I probably wont get to tearing it apart for another month and a half, but i'll let you know what I find when I do tear into it...
 
Hit or miss on the base gasket. I've had them leak and I haven't. I've done head work soon after a top rebuild and didn't change the base gasket. I only use Suzuki base gaskets.
If you pull the cylinder you will distrub the rings. A good hone is in order. I personally would replace the rings unless they are like new.
 
It has been discussed in great length before If your head gasket covers the chain tunnel ? you should be fine
 
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