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cougsfan
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I have a '78 R80/7 w/ 45K on it. I ride it roughly 2K per year these days. Still runs like a top. Over the last several years it has started leaking a bit oil on both sides. As near as I can tell it is coming from where the push rod tubes go into the engine block. Is it a big deal to replace those rubber seals? I assume I just have to pull the head. Anything special to know? Will the head gasket be re-usable or should I buy new ones. Probably time for decarbonizing the combustion chamber anyhow.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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First, I'd suggest doing a

First, I'd suggest doing a thorough clean of the engine then go for a ride or two. When you come back, blow some baby powder around the engine...the powder will really help highlight where the oil is really coming from. If you had said the leak was only on the left side, I probably would have first considered the oil pressure switch. But if it's both sides, it's probably pushrod tube seals as you suggest. With only 45K on a bike this old, it must have gone unused for a number of years. That will probably result in rubber hardening leading to the leak.

There's a couple of ways of doing this. The quick and dirty is to loosen four of the head bolts (the ones that go through the rocker towers) and slide the head/jug combo back. I think it will come back enough to allow changing of the seals. The problem with all this is that when it's ready to go back together, the cylinder base needs to be very clean and then a very light coating of Hylomar or Permatex Ultra Gray. You have to be careful not to get too much of the coating around the base of the two top studs...this is where oil runs out to migrate to the rockers for oiling. Not to mention there are two very small O-rings around the top studs. I just did my '78 R100/7 and did not have the large white o-ring but some models included that. You can't change out these O-rings if you don't pull everything completely off.

The best solution is to pull everything off. It's not complicated but one needs to be careful and clean while doing it. You would need a new gasket and o-ring set. And as you said, it would be time to clean the inside up. Also you could have the cylinders measured to be sure they're still within spec. But at 45K miles, you're probably OK.

I would recommend that you buy Oak Okleshen's top end manual. Walks you completely through the process. It's probably still $25. I got mine by email Oak at askoak at aol dot com.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

cougsfan
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I got the bike 10 years ago

I got the bike 10 years ago with 25K on it, and it had indeed been setting for years. It has always leaked a bit but has gotten considerably worse in the last year.
It is definitely leaking more on the left side than the right. but oil is present on both sides. At first I thought it was the oil pressure sending switch, and I replaced it with one I found one Ebay, but it didn't help. I suppose it is possible the replacement one leaks too.
Last night I cleaned everything, wrapped paper towels tightly around the push rod tubes rubber and started it and ran it for a few minutes, then let her set all night. Today the paper towels were fairly oily, so I am sure those push rod seals leak....but some oil had dripped somewhere near the rear of the engine too. She probably has multiple leak points! Tonight or tomorrow I will try the baby powder routine.
I would actually rather ride this old bike over my new BMW, it is much more comfy. But getting oil on my boots gets old Smile
Thanks for the suggestions.

khittner
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The oil at the rear of the

The oil at the rear of the engine is probably from a rear main seal leak, tranny input seal leak, or both. The bike is 38 years old---this stuff happens. Replace them, and they'll be good for the next 20 years. And then other 38-40 year old stuff will need rebuilding/replacing, too.

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Konrad

cougsfan
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Schraders suggestion of using

Schraders suggestion of using baby powder worked great to clarify exactly where the leaks are. It showed oil seeping from the push rod seals. Some going down to oil pan gasket then back to the rear of the pan. The push rod seal next to the side stand leaks oil on to the side stand where it runs down to the foot peg area and spreads around. I think those are the only things leaking.

I will also try his suggestion of just pull the barrels off part way because my automotive-style ring compressor won't work on pistons that go into the bore from the bottom. Do you have to have a ring compressor to install pistons or can you just compress the rings with your fingers, like on a small bore two stroke?

Now I need to order gaskets & seals, and a exhaust nut wrench and I will be ready to do it.

schrader7032
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San Antonio, TX
Joined: 10/27/2006
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You don't need a ring

You don't need a ring compressor...if you have tough finger tips, you should be able to compress the rings as you nudge the cylinder in. You could even use a large set of hose clamps...that's what I did the last time.

Not sure if you heard the word of caution on removing the exhaust nut. If you get Oak's book he'll mention this. If you start to remove an exhaust nut and after a bit of movement, it tightens up, stop immediately. You will be at a point where the aluminum threads on the exhaust port are being galled/ruined. Try various penetrants (WD-40 is not a penetrant) and hot/cold cycles to draw the penetrant in deep. After some time, try moving the exhaust nut. Time is your friend here. If nothing seems to help, get a hacksaw or Dremel and cut the exhaust nut off. You have to be careful to not go so deep as to cut into the port threads. When you have a good cut, use a cold chisel to split the nut off or use the chisel to twist the slot so that the nut can be worked off by hand. You may also need to find a metric thread file to clean up any threads that might have been damaged. Upon assembly, use a good quality high temperature anti-seize lubricant. I hear the controversy about copper, nickel...not sure it really matters, but you need anti-seize in there. You're supposed to remove the exhaust nuts yearly and renew the lubricant...I can't seem to make myself do that! I'm a little gun shy...when I was younger and more stupid and before the Internet, I ruined one exhaust port...never again!

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

cougsfan
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Thanks for the heads-up. I

Thanks for the heads-up. I will hit the exhaust nuts with some PB blaster a few times while I am waiting for parts, heating the engine up before I blast it. Those nuts probably have never been off and I will be cautious and take my time. I have the 700+ page Clymer manual, but they don't mention the important nuances like this.

cougsfan
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Got the parts today and I

Got the parts today and I took the bike apart. Things went well.

One question about base gaskets. The bike has none! It does has two O-rings that go around the top studs. I bought base o-rings that supposedly goes around the cylinder where it goes into the block but there was none installed nor is there a recess for an o-ring. There was no conventional base gasket either. The manual makes it clear that there are different configurations, but I think it would have one or the other????

Is it possible it designed for no base gasket? It wasn't leaking around the base gasket (or lack of gasket).

Ring gap is OK, and some but not too much carbon. The exhaust nuts came off easily. (Thanks for warning me to soak it in penetrating oil, Schrader). The Push Rod Tube seals were obviously shot.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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My '78 R100/7 also had no

My '78 R100/7 also had no base o-ring....I bought the bike at 13K miles so I was likely the firs inside it. Yours had 45K...probably original inside. The o-ring is a second way to help with base seepage...but using a thin layer of something like Hylomar or Ultra Gray or Yamabond or Dreibond or etc should be sufficient to keep the base from weeping or certainly slow it way down.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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