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Valve Seal Replacement Help

  • Thread starter Thread starter Weeksz
  • Start date Start date
W

Weeksz

Guest
My 81' GS750L is burning oil on start-up. I've done some picking around on here and it seems that general consensus of cause is the Valve Stem seals.

I bought this bike for my commute to work to save some money and keep miles off my car. I have plans to overhaul the bike this winter, and I would rather wait until then to get to work.

The engine stops smoking after it has been warmed up. So here is a few questions:

1). How bad is this for the bike to run with bad seals?

2). How difficult is the replacement, what is the downtime typically?

3). Does anyone have a link to a DIY?


Thanks a lot!
 
1... May oil foul the plugs if its REAL bad..but from what your saying it will just use maybe 1/2 pint or so between oil changes, but keep an eye on the sight glass anyways everytime you go to ride.

2..Down time should be just 1 long day if you really get into it. However, i also suggest that since the head is off that you also check the condition of the valves themselves for any grooves or rolled edges. Also it wouldnt hurt to have a machine shop refresh the valve seats. Its already off the bike and right there so get it all done in one swoop is my advice. make a copy from a maual of the seat grinding angles and supply that to whoever does the heads. Be sure to have a manual near by to reste the cams and check the timing when youve got it back together.

3..Like was posted in my thread with this same question, once your down to them, a little blast of heat from a heat gun just to soften the rubber a bit and they come right off with some long needle nose pliers. Heat them and then twist and pull and they will pop right off.
 
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chuck hahn said:
1... May oil foul the plugs if its REAL bad..but from what your saying it will just use maybe 1/2 pint or so between oil changes, but keep an eye on the sight glass anyways everytime you go to ride.


2..Down time should be just 1 long day if you really get into it. However, i also suggest that since the head is off that you also check the condition of the valves themselves for any grooves or rolled edges. Also it wouldnt hurt to have a machine shop refresh the valve seats. Its already off the bike and right there so get it all done in one swoop is my advice. make a copy from a maual of the seat grinding angles and supply that to whoever does the heads. Be sure to have a manual near by to reste the cams and check the timing when youve got it back together.
Click to expand...

Ok thanks, that makes me feel a bit better.

chuck hahn said:
3..Like was posted in my thread with this same question, once your down to them, a little blast of heat from a heat gun just to soften the rubber a bit and they come right off with some long needle nose pliers. Heat them and then twist and pull and they will pop right off.
Click to expand...
do you have a link to your thread page? Looked but couldn't find anything. I'd like to find some step by step action somewhere..
 
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It's one of those things that "you may as well as long as you have it apart."
So, as long as you're there, I'd put it some new piston rings and hone the cylinders. Of course, you're going to need new head and base gaskets, use Suzuki gaskets.
I'd argue with Chuck about doing it in a day. He could probably do it in a day, but, he and I have had engines apart and back together before. Unless you have everything you need and have some mechnaical experience, I feel it's more of a three or four day job. :)
 
Consensus seems to be that if you have the head off, the base gasket stands a good chance of being compromised. That means a new base gasket as Larry said. Time can add up.
 
Larry D said:
It's one of those things that "you may as well as long as you have it apart."
So, as long as you're there, I'd put it some new piston rings and hone the cylinders. Of course, you're going to need new head and base gaskets, use Suzuki gaskets.
I'd argue with Chuck about doing it in a day. He could probably do it in a day, but, he and I have had engines apart and back together before. Unless you have everything you need and have some mechnaical experience, I feel it's more of a three or four day job. :)
Click to expand...
Thats exactly how it went for me...leaking head gasket and it smoked a bit so I opened her up.

base gasket
head gasket
new rings/circlips
2 hose clamps for ring compression.
valve cover gasket
tensioner gasket ( i made from stock material)
honed cylinders (bought ball hone)
lapped valves (bought hand lapper and compound)
valve seals.
did valve adjustment.
Yup, once you get in there those are the basics cause you dont plan on being in there for a long time , save for valve adjustments.
Valve seals are easy. Pop them off and pop them on.
Get assembly lube and lube all metal to metal cantact points as described in manual.
Manual avalable for download in Cliffs site.
Its not that much work and is very rewarding.
If you do all I mentioned above it will cost 175-250 bucks for all the tools and gaskets and bits.
Remember there are sometimes special gaskets and orings/washers inside the head.
Get everything at once! Missing a couple little bits will mess up your whole rebuild flow.
 
This crowd love rebuilding engines, but you dont have to

This crowd love rebuilding engines, but you dont have to

If every thing else seems ok, (eg good compression, no funny noises, low ks) and you want to only change the seals, because your cheap.

You could try This
http://www.thegsresources.com/_forum/showthread.php?t=188696

costs $20


Cheers John
 
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Man I can't thank you guys enough. After reading all this I'm pretty confident the guys I live with and I have enough mechanical knowledge to get her stripped and rebuilt over a weekend. That's shorter than I expected.

Loud - Thanks for that list!

John - Nice! That is some really clever work there. I'm kinda leaning towards the whole teardown now. Great read though!

Chuck & Larry - Thanks, I'll let you know how long it takes me ;)
 
You can do them with the head on the engine..You can use your air compressor with an adapter that screws into the spark plug hole to hold the valves up as you change the seals. You can also take off the carbs and exhaust and use some rope inserted into the cylinder. Insert the rope and rotate the engine till the piston comes up and pushes the rope against the valves. This holds them up so the work can be done up top. You rotate the engine with the big nut thats under the points cover on the right side. Do each cylinders exhaust and intake seals and move down the line. Reset the cams, set the cam timing with the number 1 or 4 at TDC AND with the visual check of the timing mark in the points cover..refer to the manual for the proceedures... then slowly rotate the engine by hand a few times to see that all is free and theres no binding or anything else out of the ordinary.
 
You can do them with the head on the engine..You can use your air compressor with an adapter that screws into the spark plug hole to hold the valves up as you change the seals. You can also take off the carbs and exhaust and use some rope inserted into the cylinder. Insert the rope and rotate the engine till the piston comes up and pushes the rope against the valves. This holds them up so the work can be done up top. You rotate the engine with the big nut thats under the points cover on the right side. Do each cylinders exhaust and intake seals and move down the line. Reset the cams, set the cam timing with the number 1 or 4 at TDC AND with the visual check of the timing mark in the points cover..refer to the manual for the proceedures... then slowly rotate the engine by hand a few times to see that all is free and theres no binding or anything else out of the ordinary.
Click to expand...

Good write-up, its all making sense now. Thanks.

Ok before I go on anymore I just remembered. It appears that the valve covers have been removed before, from visual inspection of the red gasket. I know there is not telling what was done to a bike before(and if they did was correct), but I'm just kinda wondering what was done before... Just kind of pondering these questions in my head.





And I'm not sure, But it almost seems like the valve cover is not the original? Seems odd, I could be wrong..




 
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maybe the old gasket leaked eventually and was just replaced. In any case, if you think it best to refresh the seals and remove all and any doubt then theres no harm done.
 
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