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Old 09-23-2013, 01:01 PM   #16
dudester
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Just got a R65 (1987 year monolever). Have an R80st and also R80g/s....bought the R65 to put and R80 or R100 engine in, but after riding it yes at higher R.P.M.s can say that it needs nothing and except for low end torque can't really feel any difference from the larger bikes.....except for pushing 6-7k rpms.

Look for a good used R65,R80 or R100 engine for transplant. The monolevers are great bikes!

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Old 09-23-2013, 09:46 PM   #17
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Since this bike was never in the US I can only assume that you are in somewhere in Europe or beyond. It was very common for companies like Fallert, Wudo, Siebenrock and more to make kits to lower the horsepower on some models for insurance and registration reasons as well the offered kits to go the other way. Check with one of those companies for help as it looks like you are getting a lot of wrong info here
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Old 09-23-2013, 11:20 PM   #18
tafouras OP
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to be more specific

First thing, thank you all for your answers, forgive my bad english,I'll try to be as acurate as possible. I'm not talking about the frame, which is the same monolener the 50 hp version uses. I attach the specs ( http://www.gobookee.net/get_book.php...BCTSBCaWtlcw== ) . The vin label on the frame is writting exactly : Typ BMW 247 649 ccm.
As far as I know and correct me if I'm wrong, the R65 (27hp 47 hp and 50hp), R80, R100 have the exact same engine housing. The low tuned R65 uses a different degree camshaft in order not to advance, all the others R65 R80 and R100 use the same. Also the low tuned R65 engine uses cylinderheads with smaller inlet than the ones with 47hp and 50hp has lower compression ratio and smaller 26mm carbs.
The main cuestion is, what could go wrong if changing the camshaft, the cylinderheads the pistons and the carbs. In my opinion , this would be a safe transforming the entire engine and not a dangerous experimental tuning . Plus that by oppening the engine, is a good oportunity to check and change old seal rings, gascets, beerings and whatever else is needed. In this case I think it would be an almost new engine. How about that?

As I said before, an option is to buy a used R65 or R80 engine but it is allways a risk on what is one buying and what hidden problems the engine might have.


P.S. How do I attach images?
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Old 09-23-2013, 11:33 PM   #19
Prutser
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I think changing the cam, heads and carbs is the best option but it might be hard to find them without the engine it self.
And sometimes its even cheaper to buy the engine complete. Than you can still swap the parts onto your own engine.
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Old 09-24-2013, 06:39 AM   #20
AliBaba
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Quote:
Originally Posted by tafouras View Post

As far as I know and correct me if I'm wrong, the R65 (27hp 47 hp and 50hp), R80, R100 have the exact same engine housing.
R80 and R100 use the same housing. The R65 has a different housing (at least the angle of the pushrods are different).
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Old 09-24-2013, 12:50 PM   #21
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Originally Posted by eric2 View Post
I rode an r65ls for 12 years and about 80k miles. Waste of time to try increasing power, and they aren't that reliable to start with. Your best bet it to get a used r80 motor.

You won't get bigger jugs on the r65 as the opening in the block needs to be larger.
I beg to differ. Its only money.
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Old 09-24-2013, 01:00 PM   #22
190e
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tafouras,

You are correct in your statement about the cam, carbs and head, being a low risk strategy - If you can find the parts.

To be specific about the cam, most airheads above 600cc had the 308 cam including the 45 to 50hp R65's. The 27Hp had, believe it or not, a 256 cam. That is a very mild cam. For completeness since it's been mentioned, 35Hp R45's had a 308 and 27Hp R45's a 284. The cam numbers relate to the duration of the cam i.e. how long the valves are open although don't try to relate the 308 designation to published valve timings as it won't add up due to the published figures being quoted at a 2mm lift.

The R65 308 cam is not the same as 308's from other engines as the change in the angle of the push rods changes the cam timing if not duration. So you do need a 308 from an R65.

190e screwed with this post 09-24-2013 at 01:09 PM
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Old 09-24-2013, 09:55 PM   #23
tafouras OP
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Originally Posted by AliBaba View Post
R80 and R100 use the same housing. The R65 has a different housing (at least the angle of the pushrods are different).
Yes , after some research I did it seems you are right. This doesnt mean I am wrong about my other thoughts though do you think?
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Old 09-24-2013, 09:59 PM   #24
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Originally Posted by 190e View Post
tafouras,

You are correct in your statement about the cam, carbs and head, being a low risk strategy - If you can find the parts.

To be specific about the cam, most airheads above 600cc had the 308 cam including the 45 to 50hp R65's. The 27Hp had, believe it or not, a 256 cam. That is a very mild cam. For completeness since it's been mentioned, 35Hp R45's had a 308 and 27Hp R45's a 284. The cam numbers relate to the duration of the cam i.e. how long the valves are open although don't try to relate the 308 designation to published valve timings as it won't add up due to the published figures being quoted at a 2mm lift.

The R65 308 cam is not the same as 308's from other engines as the change in the angle of the push rods changes the cam timing if not duration. So you do need a 308 from an R65.
So you think I should go for the
308 DEG. STANDARD CAMSHAFT TWINS 1979 ON

or the
308 DEG CAMSHAFT. R45/65 1978 ON. (NOTE: THIS CAMSHAFT REQUIRES 1* 11511 INNER ROTOR)

as found in http://www.motobins.co.uk/bmw-parts....20valve%20Twin
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Old 09-24-2013, 10:39 PM   #25
Padmei
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Are airheads had to come by in Greece? I would say your first stage of research would be to see how available bigger engines are & what cost they are.
By the time you start adding individual costs of pistons, valve work, even gaskets etc etc you may be in for a big surprise at the overall cost.
There have been quite few 65s purchased on this forum over the last few months & the main concern of most owners is to get more bang out of them.
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Old 09-24-2013, 11:56 PM   #26
tafouras OP
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Originally Posted by Padmei View Post
Are airheads had to come by in Greece? I would say your first stage of research would be to see how available bigger engines are & what cost they are.
By the time you start adding individual costs of pistons, valve work, even gaskets etc etc you may be in for a big surprise at the overall cost.
There have been quite few 65s purchased on this forum over the last few months & the main concern of most owners is to get more bang out of them.
bigger used engines start from 1000 euros and going up, plus that there is a big ? about the general condition of it and the real mileage.
This is the main reason that makes me thinking of upgrading this engine, after all up to 45 to 47 hp is very much enough for me.
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Old 09-25-2013, 02:46 AM   #27
georgesgiralt
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As far as I know (and I own an '82 R65 with 180 000 + km on it which I rode myself), the early R45/R65 had a different engine (which was the basis for the post 81 other airheads...) And it is a perfect bike. Same set of barrel/pistons, same alternator, no failures. So highly reliable.
When they introduced the mono's, BMW madde a big mistake, by producing an R65 which was a small bore R80. If I'm not mistaken, everything else is the same in the R65 full power as to the R80. In France, these R65 where sold mainly to police forces. So they can be found cheap but very well worn out at junkyards. It is common, in France to put R80 barrels and piston to get a working bike out of a pile of R65 bikes....
We never saw in France the detuned version as the regulation did not ask for it.
So IMHO if you want to upgrade your bike, get a set of barrel/piston/head and carbs from an R80 and you're done. (maybe you can check in RealOem if the heads are actually different in the detuned version versus the R80)
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Old 09-25-2013, 03:08 AM   #28
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To my mind you seem to be a bit too focussed on the potential problems of a used engine. Airhead engines are generally speaking reliable long mileage engines that if remotely looked after will last a lifetime or more of use- one of the big reasons a lot of us like them.

Doing all the work you want to squeeze a bit more or a lot more life out of your restricted R65 engine will be a lot or a hell of a lot of work/time/money- it really doesn't seem worth it to me.

I know it is not want you want to hear but If I was you I would spend my time looking for a very good used 80/100 engine that has a decent service history and is in good condition, and just do that swap and then a basic check and refresh of the engine.
Chances are most airhead engines, even if a bit worn out and abused, with routine maintenance will give good service beyond what miles and years most airhead owners end up owning them and riding them for.
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Old 09-25-2013, 04:54 AM   #29
190e
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Quote:
Originally Posted by georgesgiralt View Post
As far as I know (and I own an '82 R65 with 180 000 + km on it which I rode myself), the early R45/R65 had a different engine (which was the basis for the post 81 other airheads...) And it is a perfect bike. Same set of barrel/pistons, same alternator, no failures. So highly reliable.
When they introduced the mono's, BMW madde a big mistake, by producing an R65 which was a small bore R80. If I'm not mistaken, everything else is the same in the R65 full power as to the R80. In France, these R65 where sold mainly to police forces. So they can be found cheap but very well worn out at junkyards. It is common, in France to put R80 barrels and piston to get a working bike out of a pile of R65 bikes....
We never saw in France the detuned version as the regulation did not ask for it.
So IMHO if you want to upgrade your bike, get a set of barrel/piston/head and carbs from an R80 and you're done. (maybe you can check in RealOem if the heads are actually different in the detuned version versus the R80)

Georges,

I know the 85 -on R65's used the same frame as the R80 model but are you saying it's also an R80 engine with a reduced bore rather than the shorter stroke of the earlier R65 ? That would mean it had smaller than the stock R65 82mm bore.

I'm skeptical but prepared to learn.
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Old 09-25-2013, 05:25 AM   #30
georgesgiralt
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When they planned the monoshock bikes, BMW had a will to go from 650 up to 1000 cc. And then then thought that keeping two different engines in the production line was too costly. So they used the 247 base (with some little improvements) to produce all cubic volume needed.
This is why the R65 has lost what was it's strength and attractivity : stamina, and smallness !
The R65 pre 85 is a wonderful machine, apt to compete with the 1000 even if less powerful, the last models are real dogs.
And you'd better buy an R80...
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