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1978 R100/7 Topend Overhaul

Bob's Motorwwerks in Roberts, MT

A couple of years ago I did the same work on my 1977 R100. The mileage was 84,000 and I had decided to refresh the topend in anticipation of many more trouble free miles. I sent the head, barrels and pistons (left them inside for shipping) to Bob's Motorwerks in MT. He has been an airhead mechanic for many many years. He replaced the valves and did the head work. On the barrels he wanted to hone the bores and replace the rings, advised against an oversize, which I agreed. At 84,000 miles and regular oil changes and air cleaner changes the bores were in great shape. Turn around time was very reasonable, can't remember the cost but at the time I was quite happy with the quote. Now at 105,000 miles the engine runs perfect, uses just a tiny bit of oil on a 1,000 mile trip. I leave the oil about 1/8 low on the oil dip stick. In the past I would always top it off after a few days of riding. Then it would go right back down a bit. Chris Canterbury at Boxerworks in CA sugested this idea, thanks Chris.
Regarding the connecting rod bearings, I did replace them, but in hindsight there was really no reason for doing so. Well, maybe it was because I had just got the tool to remove them and was iching to use it! Take a look inside the case and if it is clean and basically void of dark colors it is a good bet the oil change history has been good. Also give the rod a pull and push, should be no movement, there is a bit of sideways movement but that is okay if it is tiny.
I used Yamabond on the base O rings and push rod seals, so far after 21,000 mostly highway miles and higher RPM's there is zero oil leakage.
have fun with the project!
Kurt
 
I've known about Bob in Roberts, MT, although his name doesn't pop up that much. If all goes well, my heads should be at Ted's today...he said it was about a 2 week turnaround, so hopefully I'll get them back later next month. :clap
 
Best thing to do is to fit Nikasil cylinders/pistons. Depending on how you do it, you'll either be over or under your current compression ratio but not the same.
 
Best thing to do is to fit Nikasil cylinders/pistons.

If my current iron cylinders are out of spec, that is what I'll do. If not and I can rering, I'll do that...I doubt I'll get enough miles on it before the next overhaul....it will be an SEP (somebody else's problem!).
 
PRT replacement with internal circlip

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

My May build r100rs had the internal clip which probably doubled my total job time. Started with the left, right side did go quicker once my "technique" was refined. Anyone attempting this job with the internal clips is advised to buy several extras- inevitably, you'll bend a couple if it's your first rodeo.
 
Maybe a leak down and compression test once the heads are back home?

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.

Kurt, May I suggest you do a compression and leak down test once you have the heads back to determine what you might need to do with the cylinders? I rebuilt my 1975 R90S (valve job done professionally) and then I honed the cylinders and installed new rings as the compression and leak down was pretty close to spec.

DaveM
1975 R90S
2000 R1100RT
 
Dave -

I'll definitely do the tests, but more than likely I'll just measure the cylinders in the usual places and see what the dimension/ovality are and decide what to do. If they measure fine, I'll consider reringing, otherwise, I'll go for new jugs/pistons/rings. I'd rather not put it together just to check compression/leakdown only to have to take it apart again. That is what you're suggesting, right?
 
Haven't done much since before the holidays. I did get the heads off and sent to Ted Porter...got a call over the past few days...the heads are done. Just need to arrange for payment and shipping time. That was pretty great turnaround!!

I'll probably begin to order things I must have - gaskets, o-rings, exhaust nuts, etc. Once I get some time, I can take some measurements of the cylinder and see where I go from there.
 
Kurt,
Be sure to check the bores on both the top and bottom of the ring travel and on the horizontal and vertical planes. I found one of the cylinders on my R100/7 to be ovalled out at about 152,000 miles.
 
Have slept a couple of times since we talked about your rod bearings. Plastiguage them or just let them be?

Glad you are just measuring and checking out the bores rather than just blasting away at what doesnt need work or repair. Sometimes for me, like with plumbing, I go to fix one thing and then it escalates into the associated next thing and before I know it I am out at the well house turning off the pump.

You should be ready to rock and roll then in just a few days, I hope, and a cruise around FM1604 might be good..........lol....or is that still a road one cruises on. Was stuck in Beach Pavillion over at Brooke for MANY months what seems long ago. When I could get off the ward I would head out that way on my /2 or in my Porsche to just be alone and think......Now though, I hear that all that country is suburbs?????..........Anyway...God bless.......Dennis
 
I plan on a round of measurements to see where I stand and see what needs to be replaced. I ordered my first round of parts yesterday, things that I will need no matter what.

As for FM1604, it used to be called the "Death Loop" because it was a two-lane road that ran out in the country and people were getting killed by cement trucks, etc. No longer...the city has engulfed 1604...it's now a 4-lane divided highway (mostly) around the city. To get to any cruising roads, you have to go farther out now...not much farther, though.
 
getting head job

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.

My 100/7 has over 300k right now, about 65k and in a hurry I cross threaded the spark plugs resulting in the need for a helacoil insert. That required taking the heads off or leaving fileings in the jugs. Bought a valve lapping kit and proceded to make like a cavemen starting a fire. Seated both valves and 200k+ miles there are still going strong. Cost about $10.00.




___________________________________________________________________________________________________
sometimes I don't know if I should giggle at the strange things in my head...or should I be afraid?
 
I've made my first measurements of the cylinder bores. The jugs have the letter "B" stamped on them, so that is the size that I'll be looking at. I'm using a t-bar handled vernier to make the measurements. I've not done this very often...it's difficult to ensure that the t-bar is pointed exactly straight up and that the two tips are touching on exact opposite sides of the bore. I can stick my hand into the bore to turn the vernier to get to max dimensions, but the ends that touch the cylinder walls sort of "stick" and I have to keep checking to be sure they are at the maximum dimension. Is there an easier way to do this? This is what I'm using:
 

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When I have done measurements like that Kurt, I have used an inside caliper-

5620782-11.jpg


and then checked that measurement with a digital caliper. A sharpie can be used to make "quadrant" dividers and the process can begin. I kinda like that tool you have there in the picture Kurt for verifying the end result. A bore that has been run seems to have too many places that are a little different but I think that tool will work fine- just have to get the "feel" for it. Gary
 
inside mic

Can You push a ring in to the bore with a piston to use as a reference for holding the mic square?
 
Gary -

I don't have one of those...it might be easier to find the exact opposite sides of the bore. My bore gage sort of "sticks" but I'm concentrating on moving it back and forth to ensure that I've found the maximum dimension. I also use my digital calipers to read the distance. The built-in caliper seems to be accurate once I figured out how to read the dial.

franko - I don't really have a problem keeping the bore gage square...I can look at the handle to see if it is parallel (to the eye) to the centerline of the bore. The problem is moving the t-bar part of the gage to get the maximum diameter. It's a bit fiddly.
 
I made my measurements (in my limited amateur experience!). Here's what they are (in mm):

Left: Fore-aft direction:

Top - Mid - Bottom
94.01 - 94.06 - 94.06

Left: Up-down direction:
94.03 - 94.04 - 94.05

Right: Fore-aft direction:
94.06 - 94.07 - 94.07

Right: Up-down direction:
94.06 - 94.06 - 94.05

These cylinders are stamped "B" and Haynes gives the dimensions as 94.015 - 94.025. "C" cylinders would be 94.025 - 94.035. As it stands, it looks like I'm beyond spec for these. I think I'm going to find a machine shop and get them to repeat my measurements to give me the final results.
 
When I did my R100/7, I was prompted to go into the motor when I discovered a 25% drop in compression on the right side cylinder. In the absence of a huge irregularity like that, I don't see where your measurements are alarming. I certainly can't read "ovalled" in those measurements. One might expect some wear on the bores on a motor that has been run.
 
Is there a problem with inserting a ring into the cylinder and measuring end gap? This is done with a new ring, old one that came off, and top bottom and mid of the piston travel. I know this is kinda old school; but it sure does show any gaps under the ring itfelf and how much wear has actually taken place.......God bless.........Dennis
 
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