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!
PRT replacement with internal circlip
[QUOTE=20774;841785]I was happy to see that this Sep 1977 build /7 has no base o-ring and external circlips:[/QUOTE]
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?
[QUOTE=20774;841787]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.
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.[/QUOTE]
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.