I have a 79 R100RS. I just finished reading about the O-ring groove being placed at the foot of the cylinders in May 79. I haven't had my cylinders off the bike because it is new to me. Is there a way to tell if I have the groove without removing the cylinders? There is no visiable gasket against the mating surfaces where the cylinder meets the engine case. But the PO had them off and used gasket goo sealer to reassemble. What a hack.
I was under the impression that the O-ring groove was found only on Nikasil cylinders. Have I been misinformed?
Don't worry about it. There may come a day when you have to remove the cylinders for something else and then you will find out if you have the groove and the O-ring. It might be because the push rod tube seals start leaking. It it's not leaking there's no problem. As far as Nikasil goes it starts with model year 1981. There are lots of these on the used market. Most riders that need new cylinders go the used route or I think you can still find new Nikasil cylinders from the dealer and pistons. That's a nice way to do it. But there are also after market companies that do plating to your cylinders. More popular amongst other brands because we can usually find the parts for about the same as the after market coating. But a few have done it. Your bike wasn't built with Nikasil but it will fit.
It might have had nikisil cylinders put on it since new? Some bikes back then had the O-ring grooves but still didn't come with O-rings. I highly recommend using sealant with or without O-rings. Just not too much of it! You can see the iron liner if they are not nikisil.
I have the same dilema with a 1980 motor I have. The cylinders look like they are nikasil, have all the grooves and wear marks suggesting they are. Are there any part numbers to look for for?
I believe a magnet will stick to iron liners, but not the nikasils. I haven't figured out what markings (if any) distinguish nikasils from the earlier iron cylinders. The seem to have identical symbols and markings.
The engine is assembled and running. It is a 1979 Airhead. Nikasil starts in 1981 so this machine was built with iron cylinders. Yes it could have Nikasil replacements now or anytime in the future but I don't think it's a very good idea to take it apart just to see what is there now. The question was how to tell what the cylinders are from markings or any other way to tell with the engine assembled. No way to tell this I know of but I have iron cylinders and my engine will not take the OEM Nikasil replacements. It is a 1975 R90/6. This was the last year of the 97mm bore. In 1976 the base spigot of the cylinder was enlarged to 99mm. There were O-rings added and base gaskets eliminated. There are base gaskets for lowering the compression. Many combinations may be found and many combinations came from the factory, with grooves, with out grooves. I found no grooves on a 1977 R100S engine but somebody did put an O-ring on it, it was squoosed.
Below is a photo of a /5 cast sleeve barrel and a Nikasil R100 barrel from a 92 PD. Note the cooling fins are significantly bigger on the /5 barrel on the right. Nikasils also dissipate heat much more effectively and are significantly lighter (i.e. 2kg each vs 3.75kg on the cast iron barrel). Plus you can see the cast sleeve with the head removed. Haven't held a R100 cast barrel against a Nikasil to compare but for what it's worth here is a physical comparison from a couple of engines that I rebuilt recently. ____________________ "The only reason people get lost in thought is because it's unfamiliar territory" (Joe Garcia) "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D" http://www.facebook.com/groups/anzairheads/
Looks like mine are definitly Nikasil barrels. Just offered them up against a pair of 78 barrels both look identical from a size point of view but the 80 barrels aren't magnetic and once the crap was cleaned off them there's no cast liner visible. I think theres a cross over with the nikasil barrels on the late 80 machines. I've come across this before on a machine that had never been touched before we pulled the heads and barrels off.
Are you talking model year or production year? '81 model year was the beginning of NIkasil, but they began producing the '81 model around september of 1980. So if it has a post september '80 build date, it's a '81 model year.
No I'm talking about the late 1980 machines (ate brakes and points in a bean can models) this is the 2nd engine I've seen with nikasil barrels. it could well be that they both had later barrels fitted, on mine I can believe it but the other machine was very low mileage with a documented history none of which suggested they'd been changed. you never know though? I've always assumed nikasil started on production year 81.
Here's a screen capture pic of the MAX BMW parts page for my model. Being inquisitive, this is why I posed the original question for my 79. Spose the only way I'll know is to remove the jugs. (when the time comes)
