Airhead mongrel

[Devon]

I picked this up yesterday. It was running well 10 years back but the carbs needed setting up, a friend tried to set them for the woman owner but didn't know what he was doing so the bike just got abandoned and left in the corner of the garage. The seller thought she had a 1977 R80RT , the V5 says 1977 R80 but on checking the numbers it seems it is a 1977 R100RS frame fitted with a 1984 R80 engine and after market fairing.

How difficult would it have been for the bike's builder (a gent in Edinburgh) to have fitted the R80 engine to the RS frame? I think the handlebars, switch gear and wiring are from the later R80. Anybody know if the R100RS gearbox fits the R80 engine and clutch assembly or will it have been modified?

I have toyed with the idea of a bobber or cafe racer but will probably get it running again and use it as a winter hack and general work horse.

Any thoughts from the collective?

 

[Ras Thurlo]

Mod it and avoid the purple rain look


Btw

What's the name of this blue?

 

[PaulRS]

How difficult would it have been for the bike's builder (a gent in Edinburgh) to have fitted the R80 engine to the RS frame? I think the handlebars, switch gear and wiring are from the later R80. Anybody know if the R100RS gearbox fits the R80 engine and clutch assembly or will it have been modified?

Not.

The engine to frame mountings are all the same.

Gearboxes only come in 3 versions, 4-speed, old 5-speed and new 5-speed.
And any gearbox can be used on any engine with any clutch/flywheel combo, the old, heavy version, or the later, lighter one.
Just mix and match oem parts.

No modification needed here.

Remember, old Beemers are like Lego for big boys.

Paul.

 

[Rob Farmer]

Mod it and avoid the purple rain look


Btw

What's the name of this blue?

I think It's Metalic Blue - Paint Code 033/428 according to BMBikes http://bmbikes.co.uk/paintcodes/blues.htm

Likes like a real Mix there Devon. 81 on forks and what look like Honda Discs.

The 80 gearbox is the same as the 100.

I like the fairing Is it a Polaris?

 

[(RIP) Tibs]

At last, you've got yourself a real man's bike!

 

[Crapaud]

I'm surprised that you would allow that into your garage.

Let me know if you need any bits for it.

 

[Steptoe]

The whole lot has been transplanted. An 1977 RS was fitted with a rear disc brake.

 

[Devon]

I'm surprised that you would allow that into your garage.

Let me know if you need any bits for it.

Cheers Sid, I will call out around and see you It will have to earn its keep and replace my Pan as a winter hack if I keep it.

Likes like a real Mix there Devon. 81 on forks and what look like Honda Discs.

The 80 gearbox is the same as the 100.

I like the fairing Is it a Polaris?

Spot on with the disc I reckon Rob, they look identical to CX500 discs. The fairing is a Rickman

The whole lot has been transplanted. An 1977 RS was fitted with a rear disc brake.

I suspect it started out as a CX500