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Hi i just recently bought a r100rs here in norway which was 1st registered in 1977 This is my 1st Airhead.I have some question regarding the bike.

firsty the engine and frame numbers are 60405##( i left the last 2 numbers out), on realoem.com it states that it is a 8/1976 r100cs.

After looking around at different websites, i keep reading that at true 77 rs should have numbers starting at 608.
If thats true then what do i have, it is a RS now and definately not a CS? Also looking more on the web it seems to have a 1979 colour scheme ( Dark blue with silver sides of tank and orangey coloured pin srtiping. Maybe its been changed to an RS after 1979??

It is in great condition it shows 49000km on the clock, but the guy i bought it off said more like 149000 ( he bought it in holland 5 years ago).It has new delorto 38 carbs, rebuilt second hand gearbox and new clutch. I have been told it is running 9.5compression on the right cylinder but only 8.5 on the left, he couldnt explain why.

I also today noticed some oil weepage coming from somewhere around the pushrods or the barrels, not sure exactly where its coming from. I was riding it a bit hard can that be the problem, any other ideas?

As i said this is my 1st airhead, so i am not sure how it should run. It seems to like to rev from 4 to 6 or even 7000rpm, is this normal? It doesnt seem so torquey of the bottom.

I look forward to any suggestions, i have tried to upload a pic but the board att quota has been reached.

Regards,
Bob

Welcome to the forum, Bobby. Others will be along who can better answer your questions. I can tell you that a '77RS is the holy grail for a lot of us airhead lovers. Beginning with the '78 models the performance started to degrade along with other changes. A '77RS will have been painted a metallic blue from the factory and will have blue pin stripes on the wheels. Some of the early RS bikes had 40mm header pipes instead of the usual 38mm pipes. You can tell by looking at the muffler clamp which will read 2mm larger diameter than the header pipes themselves.

The oil leaks around the push rod covers are likely coming from the push rod cover seals. The early covers have a ring around them which can be judiciously tapped using a special home made tool. But if your seals are original they are likely hard and need replacing. That will involve pulling the heads, which isn't that big of a chore. You will want to read up on it though.

Since you're new to airheads you will have lots of questions which we will will rush to answer. And most of the answers will be good answers. I would collect all of the airhead maintenance manuals you can gather and spend a lot of chair time reading up on the various maintenance needs and procedures. The various manuals have way too many errors in them, but what M/C manuals don't. You won't be offending us by asking questions. We need new people to impress with our airhead acumen.

Ken

I'm not certain you can totally trust Ken's info on paint because we are much more familiar with the choices that were made for the American market than for Europe, and I don't think any of us are familiar with what special colors and other choices may have been made for the Norwegian market.

If RealOEM says it was built as a CS, then it probably was, although I don't know if they are perfect when dealing with the Norwegian market bikes either. CS's weren't supposed to exist until 1980 (as far as I knew), so who knows what's going on there? Lots of these bikes have had fairings removed or added over the years, and there's always the possibility of dealer modifications, so a bike might be built as one model and sold new as another. Also, "CS" may mean something completely different on a Norwegian model than it does on ours. Without the original dealer paperwork, there's really no way to know for sure how or when what happened.

The different compression is the most important question I see in your post. If the previous owner was guessing at the 9.5 vs. 8.5 numbers because of what a compression test was showing, then the low side probably has a real problem. If he was saying that one side actually has an 8.5 piston and the other has a 9.5 piston, then the bike will run MUCH smoother if you get that fixed. I suppose it's also possible that one cylinder head is from a smaller bike, and that would also mean the valves might not even be the same side on each side.

Since the bike was (apparently) built as one model, and now is another, different transmission, and we have this differing compression issue as well, I think it's hard to assume anything about this bike and approach everything with a sense of curiosity and "there could be anything in here" rather than any preconceived assumptions.

If you change the pushrod seals (as Ken mentions), then the heads will be off and you can determine if the heads and pistons are identical side-to-side. If not, then that's something you can figure on putting at the top of your "things to do to the bike in the near future" list.

Thank you for the great replies fellas. Yes i share yr concern on the diff compression's, it does blow bit of smoke out of the left side( lower compression side).I will have it checked asap. It starts so easily and seems to run smoothly, but like i said im not sure how the old girl is meant to run.

The guy i bought it from here in norway bought it from Holland and he himself has bought the reconditioned gear box, installed it himself and had the heads and barrel's off, i also notice some gasket type sealant on both the lower compression side rocker cover and where the pushrod enters the engine. I will go and talk a little more with him on the history.

Thanks again for the info

Welcome to the forum, Bobby. FYI, with this horizontally opposed engine'd bike....when you park it with the side stand, there can be a bit of engine oil than can seep into the left cylinder which can cause a fair amount of smoke coming out of the mufflers after start-up. It should clear up after a few moments of running. This is normal and affects all airheads that I know of when the side stand is used. Course, with use of the center stand, this shouldn't be an issue. Have fun with the bike. Sounds like you got a good one. Keep us updated as some of us live vicariously here at the forum.

If the bike has been parked for awhile and just brought back to life, there may be some drift in compression after a short amount of use. This was the case for one of my bikes anyway. If its running and not making scary noises, I would not dive into it it beyond points, plugs, timing, and carburetor until it has at least a little run time.

Welcome Bob

Yes they do make more power if you let em rev. I have never ridden one with Dellortos but I expect its even moreso.
It should still be reasonably torquey In the lower range, though not so good low down as an old norton or triumph. The RS has tall final drive too for top speed. You realise how strong they are when carrying a pillion and lots of gear, they dont notice the hills, thats what they are built for.
You will have to find a friend with one and swap bikes to compare.

Look forward to seeing some pics!

As far as posting pictures is concerned, the software thingie on the forum does not work.
You need to have the picture uploaded to a 3rd party website (Photobucket, etc), and then grab the URL and paste it between the [img] code that is one of the options above your Post A Reply field.
A too-large of an image will be cut off on the right-hand side, so keep the size smaller.

Good luck, and welcome!

Here are some pics of the bike, i changed to the lower fairing screen. Sorry a couple are a bit dark, i can take some more in better light.

That is a sweet looking bike. You are a lucky man and the envy of many beemerphiles.

If you haven't done so already you might look around for pics of a '77 R100RS. Here's a link. The silver blue ones I believe were the only color offered in the US market. Somebody here will know for sure.

https://images.search.yahoo.com/yhs/sea ... mp=yhs-004

Ken