Out of My Pay Grade Retro Mod and a Plea for Wisdom

[jrea96]

Hello all, I’ve been reading/lurking on the forum for years and have harvested tons of great information, but this is my first post. By way of introduction, my name is Jacob Rea, I live in Dallas, and I have ridden/owned motorcycles since I was 14. I currently own two bikes: a 1967 R60/2 with a sidecar and a 1978 BMW R80/7 - the impetus behind this post. Recently inspired by boredom, 70 mg of Vyvanse, and some of the accounts I’ve seen online (notable ones were: Bill Costello’s experience on OTL and Shane Balkowitsch's rebuild on Beamer & Bits) and this forum (just a few off the top of my head were Jeff Werner’s, Barryg’s, Brook Reams', anotherbmw's, and wynks’ posts) I just broke down the /7 for retro modding. I really appreciate the classic feel of the bike and outside of minor physical enhancements (shaving and shortening the subframe and fitting it to a new tail seat section), an electrical upgrade/new harness (m-unit blue and controls) and various other relatively minor improvements I most likely won’t change a ton about the overall look of the bike. As of now, my To Do list consists of:

REPLACING/ADDING:

Handlebars & clamp (renthal black 7/8”)
Taillight (flexible turn/brake system that I will inset into the subframe)
Seat/tail section (bought from Thor Strenger, who also built Bill Costello’s)
Headlight bucket with integrated speedometer (still looking. suggestions?)
Reinstalling suction funnels instead of the air filter pods. Bad idea?
Front turn signals (m-unit discs)
M-buttons for signals, ignition, etc.

AESTHETICS:

Tank, tail and front fender painted matte grayish-blue.
Cognac seat leather and grips. seat leather is diamond pattern
Rims, fork tubes, front disc rotor and rear hub TiN’d gold (does that affect braking performance?) Am I better off buying new forks than
worrying about correcting imperfections in tubes before TiN’ing? Does anyone have a lead on aftermarket TiN’d tubes?
Frame, engine block, fork slider, handlebars, spokes and nipples matte black. maybe the fork slider matches the tank?
All hardware and cylinder fins polished silver
To the extent reasonable, wires and cables hidden for minimalist look

PERFORMANCE:

Unless the collective wisdom of the boards advises otherwise, i wasn’t going to really get into the engine. Before reassembly i would replace
all gaskets, seals, bearings, etc affected by the breakdown
New Front brake pads
New brake and clutch cables
New Kustom tech seventies style brake and clutch master cylinders & levers
New battery
New coil
New rear shocks
i’ve seen people convert their rear hub to a disc. Is there a compelling reason to do so? Unlike the front, I haven’t been particularly displeased with the rear brakes.
if using existing front forks, adding progressive springs
I know I’m missing something. But what?

I'm certain that I'm missing some obvious stuff, but that is all I can think of off the top of my head. I bought this bike on eBay 4 years ago and even though it has sat idle for over a year while I was undergoing a few moves, it still starts like a champ, doesn’t leak, and rides as smoothly as one could ask. That said, I’m not 100% certain what its maintenance history was before I acquired it so all suggested mechanical repairs/improvements/inspections are fully in play. As far as a disclaimer, I have never done anything remotely similar to this before, but I’m a decent-ish welder (grandpa taught me as a kid and I’ll practice a ton before altering the subframe), I’m familiar-ish with electrical systems, and I have the 150 foot view of the workings of an airhead motorcycle down pat-ish. I'm also semi-retired with: 1) a wife who doesn’t appreciate excess time on my hands, 2) a deep interest in all aspects of the project, and 3) just enough knowledge to be dangerous/get myself in trouble, so I'm hoping to keep as much of the work in house as possible...including the paint. I do have a tendency to oversimplify things in my mind, and most likely I’m a fool, but my hope is that, with the the experience and suggestions of this board’s members, the magic of the internet and YouTube, the ripcord of a couple of local custom bike builders and mechanics who have agreed to lend a hand when I find myself in a jam, and my naive enthusiasm, I can craft my dream bike.

I know from my lurking that a great many of you have participated in these passion projects before, but what I’m asking (yet again) of the community is: Within the design/cosmetic parameters above, what would you do if you were building your dream bike with my limited skill set? What pitfalls are awaiting that I’m too ignorant to have foreseen? Is there anything that I should be doing (or even outsourcing), just because it’s easier to do now while the bike is completely dismantled? Other? I wouldn’t go so far as to say that money is no object, but if my kids need to eat potted meat & crackers for a few meals so I can up the kickass factor here, then so be it.

Thanks for reading and thank you in advance for your input. No matter what, if there is any interest, I will share my experience with y’all so at the very least you may be able to get a chuckle out of my idiocy.

Jacob

current condition


as purchased

 

[beemerphile]

A disk rear is expensive to do and all it gives you is a more difficult rear wheel removal and installation. Concentrate on the front brakes if you want it to stop better.

 

[20774]

Welcome to the forum, Jacob! You mention 7/8" bars...what about the controls...will you be changing them? They're meant for 22mm which isn't the same.

You didn't mention much about the front suspension. Are you familiar with attempts to stiffen the top plate...this can improve handling. I don't know if they're available but a good replacement is the "Toaster Tan" top plate. Here's a picture from ADV:

https://advrider.com/f/threads/upper-fork-plate.1103063/

Brook mentions it on this page:

https://brook.reams.me/bmw-motorcyl...g-stem-front-forks-and-toaster-tan-top-brace/

 

[pauls1150]

Hi Jacob, and welcome!

Air filter pods - I don't "know", but I've read several times over the years that pods (and by this, I believe you refer to "smaller separate filters") actually upset the smooth and controlled airflow into the carbs. The stock filter in its original chamber has a LOT of surface area for pulling air in. It might be interesting to go inside the carbs and see if the jets & needles are still the stock sizes...

By TiN, that's titanium nitride? Again, I don't "know", but I'd have to believe that any surface treatment of the brake rotor will reduce braking capacity - TiN on forks is supposed to reduce sliding friction! (also called "stiction") This may be helped by choosing a different pad material (and of course it's important that the rotor and pads are compatible to each other), but keep in mind that your life depends on that front brake.

Polishing the cylinder fins reduces their ability to dissipate heat ("as cast" provides more surface area); if they're in ugly shape, maybe just a light buffing...

TiN'ing the fork tubes depends on their actual condition - small scratches may be buffed out (use new fork seals and watch for leaks), but if they're dinged or out of true, that's open to discussion... I've read of some people converting to Suzuki forks on some bikes, but I don't know what fits yours.

And OF COURSE we are interested in your progress!

 

[RPGR90s]

clutch master cylinder

you stated you wanted to upgrade the clutch system to a master cylinder ( New Kustom tech seventies style brake and clutch master cylinders & levers)

What's your plan for the slave cylinder?

 

[shandeland]

In my opinion the single best thing you could do for that bike is ditch the pod filters and go back to a stock filter and air-box.
the pod filters are junk.

 

[lmo1131]

First projects are always a learning experience.

 

[brook.reams]

Some Rebuilding Advice

Hi Jacob,

Here is some input that you may want to consider.

0. Join the ABC (Airheads Beemer Club). That way you will get connected with fellow airhead owners who wrench, so you can learn from them.
- Then Contact your state's ABC Air Marshal and find out who is in your area to help you with work that you don't want to tackle and tools you need.

1. Start with the end in mind. By that, I mean state what the bike will look and what you want to learn out of the project. (You have a good start)
- I prioritize the project goals: "Must", "Want", "Nice to Have (NTH)".

2. ALWAYS set a budget. It helps you stay focused on making good decisions when trade offs come up.
- Use online parts catalogs, like MAX BMW for instance, and price out the parts you think you will need.
- Group your costs by the Must, Want and NTH of #1 above.
- Make trades offs so you always achieve Must, and get as much of Want as you can. And after that, deal with NTH.
- Assume 20% more cost than your parts estimates.
- Assume shipping and taxes add 10% to bare parts costs (YMMV, but these are real costs to you).

3. Per #1, & #2, decide what you want to invest in for new tools and add that to your budget.
- I make a list of what I want to learn, and budget for the new tools I may need.

4. Subcontract work you don't have expensive tools for, or facilities. For example:
- Boring out cylinders.
- Rebuilding heads
- Welding (unless you have the gear)
- Paint and body work
- Transmission rebuilding
- Rear drive rebuilding
And then get estimates to flesh out your budget.

5. Keep track of your actual cost as you buy parts. Monitor your budget and make trade offs as necessary.

That will get you going.

And, last, but most important, HAVE FUN AND LEARN. Don't make this a JOB.

Best.
Brook Reams.

 

[jrea96]

Thanks for the early responses, everyone. Great stuff and super helpful. Based on what I've heard so far:

- Rear Brakes stay as is.

- Air Filter Pods are history and funnels are in.

- I honestly wasn't going to change much with the front suspension other than updating the springs, but I'll reread Brooks article and explore advrider for more info. Definitely worth considering. A buddy just sent me a link to a lightly used GSXR front end that I'm sorta considering swapping out. I know purists hate the idea, but does anyone have experience with the conversion? I'm sure that modern forks will provide a boost in handling, but is the juice worth the squeeze? To be clear, going on Brook's prioritizing system, this would fall fully under "nice to have". Like I said earlier, outside of the front brakes, I have had no real complaints about the handling of the bike. Any increase in performance is always great, but this aspect of the project is being driven by "I think gold fork tubes look super cool and I have yet to find gold aftermarket stanchions that fit". As a kid I had an obsession with the bottoms of my shoes and what kind of pattern the tread left. That weird tiny detail played far too big a role in shoe purchases for a couple of years. My obsession with the TiN'ing is beginning to feel like a similar getting mired in the weeds situation.

- Great point on stiction as it relates to TiN'ing the front disc. I absolutely hadn't considered that. Another example of my inexperience.

- I am replacing all controls on the bars as well and so far everything I've bought has specified that it will work with 7/8" so I'm hopeful that won't be a problem

- I'm not sure what I'm doing with any of the excess parts. Give them away, sell them, hold on to them for posterity? All options, but I probably won't do anything at all until the bike is finished. Just in case.....

- I just joined ABC. I also have a spreadsheet setup to help with cost and process tracking.


I just heard from Thor that my seat/tail is on its way so I've spent the past two days practicing my welding so my subframe doesn't look like Frankenstein's monster.


Thanks again for your thoughts, much appreciated!

 

[barryg]

Looks like a nice project bike. It appears Brook is reading your thread, that's good; he knows his stuff. Your build is a little different in that your starting with a modified bike. Most of the bikes I start with have been modified for touring. Windjammers, Luftmeisters and all types of aftermarket stuff. Anyway good luck with your project, I'll be watching.

 

[davidh21500]

R80/7 'improvement' learning experience

Hi Jacob -

A number of years ago I spent way too much money and time attempting to 'improve' my perfectly fine '79 R80/7. What I discovered is that there is a definite limit (which I blew way past) at which 'improvements' stop adding value, and can often become detrimental. If I had it to do again, I'd limit the mechanical mods to (at the most)

1. Add additional disk to front brakes (BMW offers a conversion kit)
2. Dual-plugging the heads, if you have a problem with pinging ('79 was last year of the high-compression engines, and mine pinged horribly)
3. Lightened flywheel for better response. If the post-1981 clutch assembly can be retrofitted (not sure if crank end is different), that would be better still, as it is much lighter and stronger than anything you can do to the earlier flywheels
4. While I didn't do it, I've heard that replacing the under-tank master cylinder with the later 'on the bar' model can provide useful results
5. Upgrade the charging system, if you use a lot of accessories (GPS, lights, heated suits, etc)

The lesson learned is that Airheads are what they are. While there are many reasons to love them (I can't see myself having anything else), there is a limit to the amount of improvements that can be made.

PM me if you're interested in more details as to what I did, and why you probably don't want to follow in my footsteps.

 

[brook.reams]

Hi Jacob -

A number of years ago I spent way too much money and time attempting to 'improve' my perfectly fine '79 R80/7. What I discovered is that there is a definite limit (which I blew way past) at which 'improvements' stop adding value, and can often become detrimental.

snip ...

The lesson learned is that Airheads are what they are. While there are many reasons to love them (I can't see myself having anything else), there is a limit to the amount of improvements that can be made.

I'd like to echo David's observations about how "optimizing" components of a bike (which is a "system" of components), can lead to a sub-optimal system. An example of a "sub-optimal optimization" already called out is that the pod filters are sub-optimal. Udo Gietl, of R90S race bike fame, flow tested the clam shell and the later "black box" air cleaners to find out how well they performed. He found them excellent at providing optimal resonance frequencies at the intake valves. Pod filters disrupt that optimal "organ pipe" tuning.

That said, there are weak areas of the design that benefit from investing in improved components. Some component optimizations that improve the system that I'm aware of include:
1. If the bike has the ATE under gas tank master cylinder, invest in a "Piss cup" master cylinder on the handlebars along with a potential change in diameter of the master cylinder for better braking with better feel.
2. Upgrade the top fork plate to something more substantial (ala Toaster Tan) than the thin "evaporated milk can" steel plate BMW uses.
3. Internal fork rod upgrade to valve cartridge design (Race Tech Gold Valve for example).
4. Higher output alternator, and or LED lighting, if auxiliary electrics (lights, heated grips, heated gear) are going to be used in combination.

That said, it strikes me this project is more about an aesthetic result that doesn't fit the design concepts BMW pursued in the era this bike was built. That's fine. There's room for these kinds of builds and you can learn a lot from seeing how a nontraditional build gets done.

In reading Jacob's notes on his "end-state", I see indications of "not quite sure about this ..." sprinkled here and there that are the hallmark of a creative process. I'm wrestling with that myself right now as I get ready to start on my newest project. As in my past projects, I spend some time exploring options because that opens up the possibilities which open up more possibilities in a snow storm of ideas. But, at some point, I make a key decision about what the end-state will be. The snow storm ends and the snow ball of implementing starts rolling down the hill only picking up the relevant ideas as it goes along until the project is done.

Best of success on this project Jacob.

 

[brook.reams]

Udo Gietl Racing at Butler and Smith

This is a nice history of Butler & Smith's investment in racing BMW /5 airheads.

https://www.cyclenews.com/2018/11/article/archives-the-bavarian-underdog/

A fun read. Udo made the point that racing is about improving performance 1% here and 2% there, not just one thing at 60%. Note also the engines are designed to last for one race, about 50-100 miles. So much of what was done is not going to work well on a daily rider

Udo was the power behind the innovations at Butler and Smith, and later at Honda. I had the opportunity to meet him in 2017 at the R100RS 40th anniversary rally that Todd Trumbore hosted at his home in Pennsylvania where I also met Hans Muth, the R100RS designer. That was a treat.

Best.
Brook Reams.