R80 Cylinders > R65 Block

[jforgo]

has anyone successfully put R80 cylinders and pistons on to an R65?

It seems as if the carbs and head and exhaust would all be tranferrable -

different air intake sleeves ,connecting rods, pushrods, ?

What about cylinder - to block issues?

[20774]

Major problem...stroke on the R80 is 70.6mm while it's 61.5mm on the R65. I'm guessing the crankcase opening is different. Pushrod tubes might fit different...different length.

I suspect this is a can of worms...

[GregFeeler]

I suspect this is a can or worms...

Or worse. :bolt The R65 engine is a different animal than any of the other airhead engines.

[r60us]

You can get more info by visiting the R65 forum and doing a bit of googling. Various companies including Fallert Tuning in Germany used to offer a kit for the R65 at least 20 years ago. It consisted of a pair of shortened R100 cylinders and other goodies. Years ago I knew a fellow with a pre 1980 Fallert tuned R65; it really honked and was expensive - I believe the upgrade was $2000 at the time.The companies appear to have dropped the R65s and currently offer kits only for the R80 and R100 airheads. A much more economical solution is to trade your unmolested R65 for a R80 or R100.

[jforgo]

Thanks Kurt. I had thought somethin about the crancase opening might be different.
Of course the shorter pushrods would be coming in at an ever-so-slightly different angle. Let alone then, the main opening.

[Isamemon]

clean it up
fix it up
sell it
and get a real airhead

[Rollifahrer]

clean it up
fix it up
sell it
and get a real airhead


I hear this "red headed step child" thing every now and then.

What's not real about my bike?

[boxermaf]

Ah, pay 'em no attention, they're just jealous. Everyone knows that the R65 is the most fun in those tight twisty back roads - like a SWB R75 with better brakes ! Well, everyone that has an R65 (like I do).
:heart

[Boxerkuh]

clean it up
fix it up
sell it
and get a real airhead

Now, now... no reason to get hostile... any airhead is a good airhead... we just all prefer different model, years, for various different reasons... I like them all, but can only afford one of them... :heart

[Rollifahrer]

On second thought, let 'em think they're crappy, underpowered beemer-wannabes; that will keep the price down. In the meantime, we'll just have a blast riding the reliable sweethearts and let 'em wonder about the smug grin on our faces.

What is it dedicated oilers used to say about airheads in general? "Luddite something or other...". I guess it's all a matter of perspective.

Enjoy your ride, no matter what you put under your butt!

[GregFeeler]

Ah, pay 'em no attention, they're just jealous. Everyone knows that the R65 is the most fun in those tight twisty back roads - like a SWB R75 with better brakes ! Well, everyone that has an R65 (like I do).
:heart

BINGO! I have a SWB /5 and they are a kick in the really tight corners. I also had the use of an R65LS for a ride from Indiana to the mountains of West Virginia, then up to Rhinebeck and back. In the tight, rolling hills and mountains the R65LS was the most fun I've ever had on an airhead. The dual front disks on the LS where the real deal - you could go fast and stop well. I'll have one at some point. OH - right - this is supposed to be a secret from people looking for "real" airheads. My bad! :bolt

[jforgo]

Yes, I love the R65. Much better handling. My interest is really just to get a bit more top end, as I live in wide open space Nevada.
Perhaps I should just get a taller rear end for it?

[GregFeeler]

Yes, I love the R65. Much better handling. My interest is really just to get a bit more top end, as I live in wide open space Nevada.
Perhaps I should just get a taller rear end for it?

I live in southern Idaho and am very familiar with the big open spaces of Nevada, Utah, and parts "out West". If that were my main riding area, even as much as I love the R65's, if it were me I'd look for a different bike. The R65 is great in the twisties, but on the open road and in open country anything above 75 is really droning, and if you raise the rear end ratio I think it will just bog the bike down because you won't be able to keep it into the power rev zone. OTOH, maybe you'd like it. :scratch

[Isamemon]

I was not meaning to be hostile or bad
its just that the 65's are there own breed
parts do not interchange

but I would take a BMW650 over a honda 750

sorry
did not mean to piss anyone off:dunno

[Rollifahrer]

I was not meaning to be hostile or bad
its just that the 65's are there own breed
parts do not interchange

but I would take a BMW650 over a honda 750

sorry
did not mean to piss anyone off:dunno

Not pissed off, just taking a stand. At my very first beemer rally, the very first person I talked to informed me the R65 was the worst bike BMW ever built. Soon after at a local club breakfast I was identified as the guy who "put-putted in on that thing". I bought it simply because it fit. I have weak legs from an old injury and EVERY other beemer I sat on was way to tall. After a year of tinkering and fixing stuff the PO neglected and/or jury rigged I was very impressed by my reliable little machine. Even after getting an R1100RT, the 65 still blows my mind. When I'm on the 65 I wonder why I need 90 HP to have fun, but when I'm far from home in crap weather with sticky tires and ABS I wonder if I could continue with the same feeling of comfort and safety if I were on the 65 (not really fair as it's naked, with an aftermarket oversized windshield/sail for the rare winter ride when the RT is in pieces).

What any given person wants or needs in a bike is a continuum with advantages and trade offs, and the R65 is not the best choice for long stretches on the slab. But in every other aspect it is a real BMW; it is one of the legendary motorcycles of Germany. A term that has lost its luster in the line up designed for the global market.

[Rollifahrer]

Yes, I love the R65. Much better handling. My interest is really just to get a bit more top end, as I live in wide open space Nevada.
Perhaps I should just get a taller rear end for it?

When replacing brake shoes we discovered the FD is off an LS, and probably has a taller gear. Low end is torquey enough that I hardly notice a difference when 2-up, and it's real happy in the 4500 - 5000 rpm range, which is 70 - 75.

I have to agree, though, that a bike with longer wheelbase and taller gear might meet your needs better. I hear the R80 is a good choice.

Mark at Re-Psycle in Oh (614 837 1160) has a 65 with an R80 engine (same block, bolts light in). He can help you with your choice and help you locate an engine if that's the way you want to go.

I want another one for my wife (currently non-rider), so keep me in mind if you sell yours swauger@ee.net.

Good luck w your project,

[boxermaf]

The LS models (the stock ones in the US anyway) had the same
drive ratio (32/9) as the non Ls models. But, the brake shoes are
different due to the LS model wheels that were not used on any other model, and which had a few mm different wheel "hub" size.

There are a few (though I have never seen one) 31/9 rear ends out there somewhere, for a very slight increase in top speed potential/lower RPMs at high speed. I don't think that I'd go taller than the 32/10 rear end ratios that were used in the R80/7s. That 3.2:1 ratio instead of 3.56:1 of the stock R65 rear end would drop your RPMs down about 500 RPM at 75 MPH, but the shift in RPMs/power may not be to your liking at that speed. In theory it could raise your top redline speed about 10 mph if she will pull it. Unless it is in really good tune, the R65 won't get over 100-105 mph with stock gearing anyway.

The R65 is quite a bit quicker to rev than the R100, and it needs to
rev to make power, though it seems to be smoother than the R100
I had as well, particularly at 5500 RPM, it is like an electric motor....