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1978 R100/7 Topend Overhaul

20774

Liaison
Staff member
Well, I guess it's my time in the barrel!! I'm looking at going to Salem and have over 100K on the clock. Have been getting somewhat worried about the valves and have had some pinging off and on. So, out with Oak's manual and we're off!

Things have gone fairly well. I have not had the exhaust nuts off in, say, 25 years! I know, I know...supposed to be a yearly thing. But before the Internet, I ruined one of the exhaust ports because I didn't know that aluminum-on-aluminum galled. I was the first to take the nuts off shortly after I got the bike, so I'm not sure what really happened.

Rather than take a chance, I went straight for the hacksaw. That took me quite some time to cut through and pry the nuts apart. I'm glad I did. They were dry as a bone. Guess the anitseize I put on so many years ago sublimated!

After that, mufflers and headers. Not too bad.
 

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What not to do!

My left pushrods had a wear mark about midway...guess where the head gasket was? This is wrong folks! The right side was fine.
 

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Some serious build-up in each combustion chamber. That's the carbon that was probably glowing and setting off the fuel. I don't have lot of experience but the exhaust valve looks to be slightly deeper into the head than the intake. Here's the left side:
 

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...and the right:
 

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I was happy to see that this Sep 1977 build /7 has no base o-ring and external circlips:
 

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I'm sending the heads off to Ted Porter. I probably won't do much in the next few months unless I get fired up to move forward. I need to clean up one side of the exhaust threads...a little bunged up but really not bad. I have one of those metric thread file tools - part K-D2228. I just need to figure out how to use it.

http://www.mechanicstoolsandbits.co...h-metric-thread-file-tools-kd2228-p-4189.html

I'll also be pulling the conrods and inspecting/replacing the bearing shells. At least that's what everyone says to do.

As some point, I'll pull the jugs and see what kind of shape the cylinder is. Again, not a great deal of experience, but I see some cross-hatching on the walls...not sure how deep it is. If I'm out of spec, I'll probably be heading for new Nikasil jugs and rings.
 
Hey Kurt

Looks like a pretty neat project! You should see a lot of power with a fresh engine.

Keep the pictures coming!
 
I'll also be pulling the conrods and inspecting/replacing the bearing shells. At least that's what everyone says to do. QUOTE said:
I pulled the conrods of last year at 500,000 miles, bearings looked great!

Bolted them back on!

Just sayin!
 
I'll also be pulling the conrods and inspecting/replacing the bearing shells. At least that's what everyone says to do.
I'm not one of the "everyone" -- unless you have a rod knock, there's no reason to unbolt them, as the crank & bearings go a long time if not oil-starved. And of course, Capt. Murphy sez that if you do pull them, *something* will go wrong.

Redoing the heads and checking iron cylinders for being out of round (and maybe re-ringing/honing if within roundness specs) makes good sense at 100K; tinkering with the crank is not needed in the absence of an indication of a problem isn't.
 
Good to know about the rods...I don't really sense there's a problem...not sure I would know otherwise. I recall someone saying to pull them to check...I was this far anyway. I'll give it more thought.
 
Great Pix

Thanks for documenting this job so well.

Having just done this on a '78 Motorsport, and being a "regular guy" and not being a former (or current) machinist, mechanic, airhead guru -- here are a few observations for others following the thread:

(1) Pulling the conrods is easy, but I agree with other posters that it's probably not necessary unless you've noticed strange noises, etc. Bearing shells last a very long time. I pulled mine at over 60,000 and they showed almost NO wear whatsoever.

(2) Oak's manual is an absolute necessity unless your name is Glaves, Porter, Cutter, etc.

(3) Oak's current suggestion for a base-sealer is Loctite 510 - pricey, but a breeze to use (plenty of "open time"), and my cylinder bases have not leaked a drop. If you follow threads on this process, you'll see quite a few folks with problems in this area, SOME of whom probably used something else. Leaks mean "do over," at least to me.

(4) The Siebenrock cylinders and pistons are the berries. Porter sells them. Do it now, and you'll ride this thing into the sunset. You probably already know that it's not a good idea to go "oversize" anything on a liter Airhead.

(5) Porter does a beautiful job, and -- as with many good things, it will take awhile. From your comments, you obviously already know this. You should have -ahem - PLENTY of time to do whatever else you contemplate (such as building a full-sized, functioning Airhead out of toothpicks or something) before getting the heads back.

(6) You can make one of those pushrod seal "installation tools" out of 1/2 (ID)" PVC, and it works great. I obsessed over getting the EXACTLY right OD mm's for the pipe, finally gave up, used PVC (not exactly right), and found out that it didn't matter that much. My seals went right in, following Oak's instructions to the letter.

Walking Eagle
 
W.E. -

I bought Oak's manual 4-5 years ago in anticipation of this. I had set it aside because I had pushed the overhaul to the back burner but picked it up again to reread the critical sections. I don't recall Oak's recommendation in the manual for a base sealer, but Ted Porter has recommended Permatex Ultra Gray.

Yup, I've read how it's probably not recommended to try and oversize the liter cylinders. But I have to make my measurements first, then decide. Ted is my first choice, but I've gotten a few off-line comments as well about his turnaround time. Earlier this fall, I read on another forum where he turned around a set of /6 heads in two weeks. They must have caught him at a slow period. I intend to email him and get some information about the job and then really try and keep him to it. I want to get this together with time to properly break it in before the summer trip.

I'm not sure what you mean by installing the PRT seals. The seals install themselves as far as I know. If you're talking about the collar to provide the right pressure on them, I'm not a big fan of driving that collar tighter. I will observe where the collar currently is. I also have a drawing from Oak (I've posted a semblance of that in the past) about where the collar needs to be relative to the cylinder base flange. If necessary, I will adjust by using the proper tool to move the pushrod tubes around. I've had to do that on my /2.
 
Same bike here:)

I have the R100/7 since new, with 388000m now. My heads are original and I have taken them off every 50-75000m or so to clean'em, if that! My compression is still near the top of scale. I bored it and did first oversize at 104000 with rings and valve guides, thats all. Did NOT need to, but had already bought the parts, holding'em in hand. Did all the work myself. I know I am nearing the same job someday(lol), but the bike has been amazing and surprises me how well made it is. Knowing what I know today about mine, the 100000m mark is just a well broken in engine on a /7 model. I have interest to know what the HEAD JOB cost with Ted P. .? He is well respected and I live only 3 hours from his locale, never met the man. I saw him in Sedalia at the rally this year, as he had a vendor booth. Randy:thumb
 
Kurt, the reason you had rub marks on one pushrod is because of the head gasket. Look at it --- it's on backwards. Flip it over.

Been there; done that!
 
Kurt, the reason you had rub marks on one pushrod is because of the head gasket. Look at it --- it's on backwards. Flip it over.

Yup! I knew that once I looked at it. That's why I said that was wrong!! This was a result of me doing a ring replacement back in 1983 after being concerned about the level of oil use. I replaced the rings with Luftmeister 3-piece rings. Since it was before the Internet, I didn't know about the orientation of the gasket and put it on wrong. It won't happen again, for sure!
 
I have interest to know what the HEAD JOB cost with Ted P. .?

I have an email into him right now to get a quote. I asked him about this in February 2011 when I was thinking about it, but put it off. It was $685.00/pair and he said he uses the Euro two piece exhaust valves and the steel alloy intake valves.
 
Pushrod Seals. . .

Not suggesting that anything be "driven" -- that might dislodge the tubes from the heads, which is a very bad thing to do! Either a little hand pressure, or LIGHT taps of a plastic hammer is the ticket.

The PVC tool is probably "optional" but does "ease" the lubed seals into the cases quite nicely, whilst snugging-up the two LOWER nuts as everything comes together, cylinder always being kept parallel to the cases.

If you've got an older manual, which you do, it won't include the "latest" base-sealant info, which is to use Loctite 510. As with the dreaded oil threads, everybody has a different opinion; many base-sealants/"gasket replacements" will work just fine. Me? I always ask: "What would Oak do?. . ."

For other pressing questions in my life, I always ask: "What would Willie (Nelson) do?"

The price quoted by Porter is probably still in the ballpark, and includes NEW "everything" -- valves, machine work, seats, springs. . .etc. (but strangely not the keepers - send him yours if you dis-assemble the heads). Some of the advertised prices for head work (adverts in our various periodicals) ONLY include the machine work and seat replacement, so be sure you (the "collective" you) understand the menu pricing. Never heard a complaint about the quality of Ted's work, only about the turn-around times. The heads are returned fully assembled and ready to rock.

Walking Eagle, out
 
Though I totally resist tearing down further than needed to fix what's wrong, IF IT AIN'T BROKE DON'T FIX IT, as long as you are down into the internals really nothing wrong with checking out the rod bearings. PLASTIGUAGE is readily available at most engine speed shops or overhaul outfits. Using this stuff is a tried and true method for checking bearing clearance and wear......

For me, measuring Ring End Gap, pretty much tells me what I need to know in deciding whether to bore, replace rings, or just leave it be. Have you done a compression test to check out if you even need repair/replacement?......It really is worth the effort before disturbing the current "seal" your rings, cylinder, and piston is making. OOOOPS, you already have it torn down. So no compression check; but easy to check that end gap and put some calipers to the piston/cylinder.........God bless.......Dennis
 
Have you done a compression test to check out if you even need repair/replacement?......It really is worth the effort before disturbing the current "seal" your rings, cylinder, and piston is making. OOOOPS, you already have it torn down. So no compression check; but easy to check that end gap and put some calipers to the piston/cylinder

The "need" in this case was many miles on the leaded upper end and general concern about dropping a valve. The valve clearance has remained fairly steady, although just weeks prior to heading for the Bloomsburg rally, I found the valve clearances had closed up. I decided to reset them and ended up checking the valves at various stages along the way...only to find them remaining where I had reset them. I didn't like that feeling, not knowing if I was sitting on something about ready to explode.

I mentioned the occasional pinging...probably due to the build up in the chamber...also probably due to the additives I was adding to stave off valve recession, or the possibility of it. Once I do the top end, I don't have to worry about that anymore.

I'm not going to go at this by doing the minimum...I've gone this far so I figure it's no big deal to do a complete refresh or at least take the measurements. Peace of mind. If I got this 100K in a little over 30 years, I suspect if I do this right, the next refresh will be someone else's problem!
 
Thanks for posting this. I plan on replacing pushrod seals right after rear main seal/oil pump o ring as soon as I can get the clutch out! I did a pushrod seal replacement before and didn't use any tool to set the seals, just pressed them in place. They seem to be working still after several years. Maybe beginners' luck!
 
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