R100 Performance mods..... cafe racer.

[comaboy]

howdi,
I picked up a cheap old R100 which is running, but only just.

I am looking at stripping it down, checking it out and rebuilding it into a cafe race.

So far Im going to do the following.

Big bore kit
310 cam
bigger valves and porting heads
lightening flywheel.

Ideally I would like to get 100hp out of the beast, but 90 would be ok. Where can I pick up the parts to do this, and can anyone guide me as to what to and more importantly what NOT to do re engine mods.

I hear boxers are kind of sensitive when it comes to matching the exhaust, what should I do regards this.

Cheers

ComaBoy

[dwerbil]

Welcome comaboy! Sounds like a blast of a project.

[Motorhead]

312 cam
40mm exhaust

turbo charge it................ 90 to 100 hp

[Major Softie]

Yeah, you're not going to get anywhere near 100 hp normally aspirated, but you can still make it pretty hot with the kinds of mods you're looking toward.

[comaboy]

Anybody know where I can pick up the cams, big bore kit and lightened flywheel? If it comes down to machining the flywheel, how much weight can I knock off before it starts to become dangerous? Does anyone make a lighten'd flywheel for the airhead? anyone make a turbo for such a beast?

I have been googling but am yet to find what I am looking for.

Cheers

CB

[chasbmw]

Comaboy, welcome to Boxerworks, some information from you will help us point you in the right direction,

What year bike?

Where are you from?

A normal R100 produces less than 50bhp at the rear wheel, so the only engines I know of that get into the 90s will be full race bikes.

Do you have a budget for engine mods?

Cheers. Charles

[Deleted User 72]

Welcome to the asylum.

The later flywheel ('84 on(?)) is as light as anything you can build and comes with a much better clutch. You'll need the later transmission input shaft to go with it.

Motoren-Israel has most of the rest of the stuff you want http://www.motoren-israel.com/index.php?language=en, but I'd check out Motobins first http://www.motobins.co.uk/bmw-parts.php ... lve%20Twin . You might find what you want at a better price.

[SteveD]

9/1980 on flywheel...the models with the square airbox.

Siebenrock 1030 or 1050 kit..I forget which size.

Maybe a carb change..dells or mikuni's?

Chassis stiffening and suspension work will help.

336 cam, krauser 4v heads?

Weightloss, rider school...

There's always Dr. Curve to reference. http://mailer.fsu.edu/~jroche/road_rod.html

[Motorhead]

Luftmeister is the outfit they made the turbo and exhaust sometime they show up ebay and IBMWR

motorad Isreal is a good outfit

Ken has some modfied frames for sale in IBMWR

[comaboy]

Hi again and thanks for the welcome guys,

The Bike is a 1980 R100RS. Perhaps 100HP was a bit optimistic after all. I would like to fully race prepare the engine if I could to try and get the most I could from it without going to Forced induction (it somehow seems wrong). I also have a BMW 1986 model R65 that my father left me when he died.

I honestly used to wonder what the old blokes at the Ulysses club meeting were on about, the way they spoke in hushed tones and their eyes would glaze over as they told tales of their wondrous old R100 or R80.

But since I rode dads bike, I honestly think I get it. There's something pure, something that speaks to you and says that this is how motorcycling should be.

I hate to admit it, but the old bugger was right.

Im in Melbourne Australia.

CB