A very nice 79 edition R65 that one.
Be aware when ordering parts that some things are unique to the 1979/80 model and changed thereafter.
A non-exhaustive list is:
carbs- flat top Bings on 79/80 and domed thereafter
Seat ducktail (and storage unit under it)
Side stand - if you need a new bush order from the /7 catalogue as the R65 part will not fit.
You may have a tacho with a mysterious yellow LED that flashes briefly when starting with a somewhat depleted battery. There is a whole saga behind what this is and a now departed member "Rev Light" took his name from it. It's an over-rev warning by the way, not surprisingly it was deleted in later models as it was unlikely to be seen "in the heat of battle".
Ignition, you have "points in a can" unique to the 79/80 R65s, later models have the same "bean can" but it has a hall effect transistor arrangement in it, not points.
Because of the above you model uses two seperate ignition coils very much different to the later models. - You can upgrade the entire ignition system to the later standard, or fit something like a Boyer system to your existing arrangement (my wife's R65/80 has a boyer unit with total reliability since it was fitted circa 1991.
If ever your bike develops the fault of only being willing to start if you pull in the clutch lever then you have suffered the dreaded diode failure. A suitable replacement diode costs 10c, but knowing where to find the blasted thing in the wiring harness is the trick, depending on the source of your wiring diagram it may or may not be shown.
You have "iron" bores and later model have silicon carbide bores - this is only relevant when buying rings, If the rings suitable for iron bore engines ever becomes NLA, the rings from an R75 will fit, my memory telsl me to check/adjust end gaps, but that may be because I used an oversized set of R75 rings, the R75 and R65 share the same bore.
Your model has slightly different pistons, I don't think this is a biggie as I have 79/80 pistons in my 84 edition (but with late model heads) and it lost a merest amount of compression, if you were to fit late model pistons you would gain an equally irrelevant amount of compression.
You will probably have small valve heads, these lead to the rather anaemic performance of early R65s, they are also more prone to the dread dropped valve than the later ones (which also drop valves if not maintained, they just take longer and more abuse to do it). If you find your heads in need of refurbishment, I would hunt a later model set and enjoy the near 10hp increase.
You have an ATE near copy of a Brembo FO8 brake caliper. The ATE calipers are fine and dandy, but they require a different pad to the Brembos and if/when they require rebuild you will inevitably be buying new pistons for it as ATE made a less than stella decision on what to make their pistons out of. The good news is that Brembo FO8s will bolt right up and will cost you brand new about what a new pair of pistons and a rebuild kit will cost for the ATE. If you stick with the ATE (my wife has) then be warned that when oyu say ATE brakes to a BMW parts seller, they immediately think of the "swinging caliper" brakes fitted to /6 and /7 bikes, The only part those have in common with yours is the bleed nipple.
Your clutch pack and clutch disc is unique to the 79/80 R65, from 1981 the desing of the flywheel and clutch was altered and all airheads share the new flywheel and clutch. This change required a change to the input shaft of the gear box so retrofitting the later flywheel and clutch is non-trivial.
The final drive housing is shared with the /7, 1981 on has the later housing, the ratios are the same however. Your model also has a "unique" means of coupling the gear lever to the gearbox - a piece of bent wire disguised by a rubber cover. You can buy an adjustable rose joint from your local engineering/bearing shop, it is a 30 minute job to swap over and your gear lever height then becomes adjustable - while you are there the bush that the footpeg mounted gear lever turns on will be flogged out because BMW under spec'd it - strips cut from aluminium drink cans will take up the slop until you get around to takign it all to a machine shop and have a new bronze bush made up and inserted.
There are more differences, I'll leave them for others, but congratulations you own a fascinating little bike that will provide you with astounding service and only requires minimal but regular maintenance to do so.
