The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: manxr65 on September 24, 2010, 10:16:25 AM

Title: r100 engine in r65 frame
Post by: manxr65 on September 24, 2010, 10:16:25 AM

is it possible to put an r100 engine into a r65 frame , frame type 248

Title: Re: r100 engine in r65 frame
Post by: Rob Valdez 79 R65 on September 24, 2010, 03:48:20 PM

Yes, but the cylinders extend further, possibly limiting your lean angle.
There are no other concessions.  Everything bolts right up, provided you have matching clutch assy to transmission.

Title: Re: r100 engine in r65 frame
Post by: manxr65 on September 24, 2010, 04:48:54 PM

thats great , will i need to change the coils or will they be ok to, also if i put  an r65 gearbox on will i be ok or is the 100 better

Title: Re: r100 engine in r65 frame
Post by: Rob Valdez 79 R65 on September 24, 2010, 05:57:48 PM

Coils will be fine.  
In 1981 BMW changed the clutch design.  Post '80 gearbox will not work with a pre '81 clutch, unless you wanted to put a earlier input shaft in the later gearbox.

Title: Re: r100 engine in r65 frame
Post by: nhmaf on September 24, 2010, 08:57:33 PM

The transmissions of the same vintage years are identical among the bikes, manxr65, so gearbox from a 1982 R65 is the same as a 1982 R80 or 1982 R100.
As Rob said, the clutch assembly and input shaft on the transmissions changed, so if you've got a 1978-1980 R65 gearbox, get a similar year R80 or R100 engine and it will bolt on.  If your R65 is 1981-1984, look for same vintage R100/R80 powerplant.  The final drives at the rear wheel are different for the bike (and the ratios are matched to the ratio in the speedometers) so you'd either had a lower top end speed (but a strong tendency to wheelie in most all gears) with the R65 final drive, or change the final drive and speedometer (or get your speedometer recalibrated by Palo Alto Speedo).

Title: Re: r100 engine in r65 frame
Post by: manxr65 on September 25, 2010, 02:22:51 AM

thats great thanks, lucky for me i had to change a spring in gearbox early on this year and noticed that the gearbox case had 78/79 on it , so i order seals and gaskets  but i found i was short a seal and realised that the internals are different , must be a recon , the arm which pushes the clutch in has an adjuster on it making this gearbox 81 on . so i now need an engine 81 on if anyone has one .

Title: Re: r100 engine in r65 frame
Post by: Rob Valdez 79 R65 on September 27, 2010, 04:31:50 PM

Quote

so i now need an engine 81 on if anyone has one .

Sounds like that should be posted in the Want Ads.

You are talking a R100 engine, still, right?

Title: Re: r100 engine in r65 frame
Post by: nhmaf on September 27, 2010, 10:24:48 PM

Post on the ibmwr.org airheads-parts wanted section and you'll likely get some hits.