Frankenbike's Birth (or an abortion?)

[TouringDave]

[bmwhacker]

Not much activity on the project lately....have it sitting on a trailer in anticipation of moving to AZ. in a few weeks.....

The QSL solo seat is just sitting on the frame...I loaned the mounting bracket to a friend so he could fabricate one for a seat he has......the seat will sit higher with the mounting frame under it......



The old Bates Bags are mounted with some 2 point brackets that came with them. I would not trust them very far.......I found a pair of different frame type mounts via EBay which will be a "quick release" style mount......these were locked when I bought them ($75.00) and I had a key which fit them perfectly......the bags will swap out with my other bikes' suitcase bags when the Tug is running....







This is the 1973 1/2 R75/5 long wheel base sub frame after installation.....so we have;
a 1974 R90/6 main frame, a 1973 R75/5 LWB rear sub frame, a 1977 R100S engine, a 1974 /6 5 speed kick start equiped transmission, "a who knows what year" leading link front suspension, a 1975(?) /6 German Cop Tank, a 1971 BMW steering friction damper, and a lot of misc. year small parts and pieces.........





Quite a bit stouter sub frame ( two cross braces) than the 74 and later models...


Found a pair of original "cigar" style /5 mufflers on EBay for $71.00 a while back...that beats the $525.00 price tag on the reproduction ones available now......This bike below is my current tug...a 900cc 1973 LWB R75/5......the BMW suitcase bags will swap over to the Frankenbike as will the floor boards, and side covers....the R75/5 will be a solo bike again......too bad I'm not into farming anymore cause I could haul a bail of hay on the luggage rack.......

[Wngnut]

Hey!!! That looks pretty Awesome!!!!!

[bmwhacker]

A friend of mine asked me if I was going to pinstripe the tank.......At this point I have about 5 shades of black going on and I think that pin striping would deter from the "I don't really care" visual effect I'm going for......

[BMWzenrider]

Originally Posted by bmwhacker

This was a "craigslist" find that in a former life was pulling a hack...

So now I needed a frame donor...found this one for $300.00 and drug it home from Las Vegas....

Did some more snooping around in my neighborhood and found this long forgotton R90/6......had been sitting outside for 6 years or so..luckily in a desert climate....
She had seen better days but for $350.00 I couldn't pass her up....

Ok...
How do you just "FIND" all of these great deals on nearly complete old Airheads?!?!?!

Around here, there is some guy who has been advertizing his /5 on Craigslist for $7,000!!!
You cannot find an Airhead in any condition for less than $1200, even if it doesn't run...

I want to know where you shop...

[bmwhacker]

Originally Posted by BMWzenrider

Ok...
How do you just "FIND" all of these great deals on nearly complete old Airheads?!?!?!

Around here, there is some guy who has been advertizing his /5 on Craigslist for $7,000!!!
You cannot find an Airhead in any condition for less than $1200, even if it doesn't run...

I want to know where you shop...

My construction management job takes me all over the Western US so I "Fish" constantly on Craigslist where ever my travels take me......local "penny savers' etc.....the "cheepo" finds seem to be getting few and far between lately......but I keep snooping around......I always keep my eyes peeled in alleys, small towns ect......The hook is that we 'full time" in our motorhome so space is limited when on the road...I always try to keep trailer space for one more bike...I have a lot in AZ. and the overflow stuff stays in a shed there...most extra crap goes to EBay to help finance these projects.....

bought this via Craigslist summer before last for a hundred bucks...bought it sight unseen and didn't know what it was til I picked it up.....The gal had been mowing around it for two years and offered (over the phone) to give it to me....I asked her how much she had into it? "$100.00"...... she just wanted it to go away.....of course the tank was restored for my use....I had never seen a "Heinrich" fuel tank so didn't really know what it was when I picked it up.....


Took some searching to find an original ( a little rough) tool box cover, a new lock set and a fuel cap. Tank had no bondo or rust and turned out pretty nice....if you like giant fuel tanks.....good for sidecar use anyway.





Really "splurged" on this one two years ago.....$1200.00.....the R90 top end and hack lives again.....



Paid two hundred for this poor lost soul last fall.......a lot of missing stuff, but a lot of boxes of good stuff too.....

[BMWzenrider]

Originally Posted by bmwhacker

After some inquiries I find that the 1978 model R100 BMW engine did not use base gaskets but rather just a sealant...mine had base gaskets, which went into the "round file".

The base gaskets were added by some owners as a way to deal with pre-ignition/pinging in the early days of lower octane fuels. Higher compression ratios require higher octane fuels.
The CORRECT way to deal with this issue is with proper valve tuning, timing and if needed, dual-plugging. Also, a worn/stretched cam chain can change your valve timing which will affect your C.R. and preignition...

Originally Posted by bmwhacker

Engine top end assembled....decided to go to pod type air filters. Engine should breath a little better.

I am NOT a fan of the aftermarket air filters unless they use a paper element similar to the stock media. It has been shown in many tests that the stock filters flow plenty of air to feed a 1000cc boxer engine when used with a drilled clamshell airbox.

All the foam/cotton/etc. filters do for your engine is let more grit into the wear surfaces of your engine. That is not opinion, it is backed up by performance numbers on the dyno.

And on the later R100 Airheads with the twin-tube air intakes, removing the airbox actually DECREASES performance!
Those clever German engineers designed those intake snorkles to create a standing pulse wave inside them to help pack air into the carburators. That is why they are different sizes (for different rpm bands).

For the R80 models there was actually a service bulletin about modifying the snorkels to make the airbox perform properly with that displacement engine. So it is not just for show.

Originally Posted by bmwhacker

I would like to have used the bigger Heinrich tank on this frame but the Heinrich tank does not allow clearance for the under tank brake master cylinder...I hunted down this old German Cop Radio tank to use....not near the fuel capacity of the Heinrich though.....6 gallons vs 8 gallons.

You would be able to use your Heinrich tank if you chose to go with a handlebar mounted master brake cylinder. Which is the correct setup for the twin-piston brembo calipers in the first place...

You get an added advantages of losing the play/slack/stretch in the cable to the undertank cylinder for a better lever feel and more usable lever travel, AND the choice of at least FOUR different M/C diameters to customize the lever feel, travel, and mechanical advantage of the setup.

In my not so humble opinion, if you started this excersize in part to improve the braking, you owe it to yourself to step on up to the handlebar mounted master cylinder setup and get the full potential out of the new calipers.

-----

On my 1982 R100RT with two 38mm Brembo calipers I swapped out the stock 15mm master cylinder for a smaller 14mm unit and found that it took less lever effort, the lever gave more feedback, and that I still had LOTS of travel available at the lever.

The ratio of caliper piston to lever piston areas for the stock setup from the factory was a rather low 25.7:1.
With the 14mm m/c the lever ratio increased by a relatively modest 15% to 29.5:1, and the effect was noticable.
The modern Oilhead models use a brake lever ratio of 36.3:1, that is a 41% increase in overall mechanical advantage over the stock Airhead Brembo setup!

Of course, with our current R65 monolever, I added a second 48mm caliper to the one that came standard on that model. A much larger caliper than the 38mm units. With the 15mm m/c in it the brake lever ratio is a nose standing 41.0:1!!!
But it stops RIGHT NOW when I want it too...

Looking at the photos of your new front end, I cannot identify the brake calipers being used.

If you can tell me the piston diameter and number of pistons in each caliper, I could recommend one or two different master cylinder sizes that I feel would be the best to use along with them for best braking feel/effort/etc...

OR, I have a spread-sheet that I set up which has the basics already laid out which you could use to plug in your own numbers and you could play with different options at your leisure...

[bmwhacker]

Originally Posted by BMWzenrider

The base gaskets were added by some owners as a way to deal with pre-ignition/pinging in the early days of lower octane fuels. Higher compression ratios require higher octane fuels.
The CORRECT way to deal with this issue is with proper valve tuning, timing and if needed, dual-plugging. Also, a worn/stretched cam chain can change your valve timing which will affect your C.R. and preignition...



I am NOT a fan of the aftermarket air filters unless they use a paper element similar to the stock media. It has been shown in many tests that the stock filters flow plenty of air to feed a 1000cc boxer engine when used with a drilled clamshell airbox.

All the foam/cotton/etc. filters do for your engine is let more grit into the wear surfaces of your engine. That is not opinion, it is backed up by performance numbers on the dyno.

And on the later R100 Airheads with the twin-tube air intakes, removing the airbox actually DECREASES performance!
Those clever German engineers designed those intake snorkles to create a standing pulse wave inside them to help pack air into the carburators. That is why they are different sizes (for different rpm bands).

For the R80 models there was actually a service bulletin about modifying the snorkels to make the airbox perform properly with that displacement engine. So it is not just for show.




You would be able to use your Heinrich tank if you chose to go with a handlebar mounted master brake cylinder. Which is the correct setup for the twin-piston brembo calipers in the first place...

You get an added advantages of losing the play/slack/stretch in the cable to the undertank cylinder for a better lever feel and more usable lever travel, AND the choice of at least FOUR different M/C diameters to customize the lever feel, travel, and mechanical advantage of the setup.

In my not so humble opinion, if you started this excersize in part to improve the braking, you owe it to yourself to step on up to the handlebar mounted master cylinder setup and get the full potential out of the new calipers.

-----

On my 1982 R100RT with two 38mm Brembo calipers I swapped out the stock 15mm master cylinder for a smaller 14mm unit and found that it took less lever effort, the lever gave more feedback, and that I still had LOTS of travel available at the lever.

The ratio of caliper piston to lever piston areas for the stock setup from the factory was a rather low 25.7:1.
With the 14mm m/c the lever ratio increased by a relatively modest 15% to 29.5:1, and the effect was noticable.
The modern Oilhead models use a brake lever ratio of 36.3:1, that is a 41% increase in overall mechanical advantage over the stock Airhead Brembo setup!

Of course, with our current R65 monolever, I added a second 48mm caliper to the one that came standard on that model. A much larger caliper than the 38mm units. With the 15mm m/c in it the brake lever ratio is a nose standing 41.0:1!!!
But it stops RIGHT NOW when I want it too...

Looking at the photos of your new front end, I cannot identify the brake calipers being used.

If you can tell me the piston diameter and number of pistons in each caliper, I could recommend one or two different master cylinder sizes that I feel would be the best to use along with them for best braking feel/effort/etc...

OR, I have a spread-sheet that I set up which has the basics already laid out which you could use to plug in your own numbers and you could play with different options at your leisure...

Thanks abunch for the input.....I've heard nothing good about the "under tank master' set ups...I was hoping to keep the /6 handle bar controls but nothing is sacred in this project.....Those "air pods" are my first such experiment....and they are cheap ones...I'll definately rethink using the stock drilled air box...my biggest investment was freshening up the engine top end...no sense in ruining it with crap air filters....many years ago I restored an old "Opel GT"....modifying the stock snorkel type air intake also decreased performance......keep the input coming...I'm all ears...

[BMWzenrider]

Originally Posted by bmwhacker

bought this via Craigslist summer before last for a hundred bucks...bought it sight unseen and didn't know what it was til I picked it up.....The gal had been mowing around it for two years and offered (over the phone) to give it to me....I asked her how much she had into it? "$100.00"...... she just wanted it to go away.....of course the tank was restored for my use....I had never seen a "Heinrich" fuel tank so didn't really know what it was when I picked it up.....


Took some searching to find an original ( a little rough) tool box cover, a new lock set and a fuel cap. Tank had no bondo or rust and turned out pretty nice....if you like giant fuel tanks.....good for sidecar use anyway.

You DO know what a steal just the tank was for that price, right???

BTW - looking at the first photo showing where the rubber kneepad used to be on that Heinrich tank reminded me that I believe there is one of those kneepads sitting in one of my parts drawers right at this moment.
I was given a pair of them by an old timer when I bought my first BMW to use as mudflaps, cause he just had them laying around and couldn't remember what they were for. I was new to the brand, so I had no idea either. So I trimmed one of them a bit and mounted it to the bottom of my front fender!

At least there is still one surviving to use as a template for the other side...

[bmwhacker]

I was quite pleased when I found out what the Heinrich tanks are worth
I bought some repro Heinrich tank pads from a guy in NY....he also supplied the Neiman lock set and NOS fuel cap......the repro tank pads are smaller and the "rear nut" pad didn't fit this narrower tank at all....I carved it down and installed it anyway....This one apparently is an 8.0 gallon tank...that is all I've stuffed in it anyway.....a lot of them were 10 gallon tanks I think......appears that Heinrich made a lot of tanks of different capacity. The tool box opening in the top is not perfectly centered either......tank had no bondo or damage when I stripped it to bare metal.....It must have been fabricated/welded together on a Monday or Friday....or right after "Oktoberfest"......

the tool box opening seems to sit a little right of center.......

[BMWzenrider]

Originally Posted by bmwhacker

Thanks abunch for the input.....I've heard nothing good about the "under tank master' set ups...I was hoping to keep the /6 handle bar controls but nothing is sacred in this project.....Those "air pods" are my first such experiment....and they are cheap ones...I'll definately rethink using the stock drilled air box...my biggest investment was freshening up the engine top end...no sense in ruining it with crap air filters....many years ago I restored an old "Opel GT"....modifying the stock snorkel type air intake also decreased performance......keep the input coming...I'm all ears...

Actually, dug this out of the bookmarks:

This is a chart showing lever ratios for various caliper sizes versus master cylinder diameter.
http://www.vintagebrake.com/mastercylinder.htm

This is the website that got me started down the path of brake tuning...
Before that I just accepted whatever the factory chose to give me.

-----

You will notice that the author at that site tends to like a slightly lower lever ratio than I do.
It is all a matter of taste, riding style, and to some extent the actual caliper being used.
Each setup has a different amount of flex in the caliper, swell in the lines, and there is even some mechanical advantage built in at the lever-to-piston interface at the master cylinder that varies between brands/models.
{He also works on some brakes that are even more primitive than the BMW ATE calipers!!!}

It does sometimes take some trials to find the "perfect" setup for yourself. But the chart is an EXCELLENT guide to get you on your way!

BTW - the BMW /7 handlebar master cylinders are available in 13/14/15/16mm sizes. The pistons are all interchangable on the base throttle assembly from any 1981-1995 R80/R100 model.
Your best bet would be to find a throttle grip from a 81-84 unit, as those came with 40mm carbs, so it will have the correct throttle gears/cam for your setup. The later models had 32mm carbs, and I believe there were different gears in the grip for those.
(The under-tank m/c only came in 14/16/17mm sizes.)

IMHO, the best place to compare part numbers, etc. is the Max BMW online fiche. It is fast, easy to navigate, and kept up to date.
http://www.maxbmwmotorcycles.com/fiche/fiche.aspx
Just click on the model/year and it takes you right to the complete fiche for that bike!
Add parts to the cart to save the part numbers if you want to compare them against each other from different models/years. Simple!!!

[bmwhacker]

Now that is food for thought.. ..might need to stretch the frame a bit though......900cc + 1000cc = 1900cc........



Seems like there are always some left over parts....



box of snakes.....



Now I can dream....wish all this "junk" was in my back yard.........