Restoring a 1973 BMW R75/5 Motorcycle

May 20, 2007

Blind luck

Filed under: 1973, airhead, BMW motorcycle, motorcycle restoration, R75/5 — Penforhire @ 6:05 pm

I got my frame back from powdercoating!


And a box of coated parts! Woo hoo!


How much would YOU pay for to powder coat the frame, a dozen more parts, and bead blast two wheel hubs (I wanted to fast-track wheel assembly)? They had to degrease (I removed the caked-on grease), bead blast to remove all corrosion, mask all threaded holes, spray-coat (all in semi-gloss black) & bake. How about $225? That’s a serious bargain at AAA Coating in South El Monte. There are a couple of tiny defects (geez, Gary sure can find ’em fast) and they did not mask all the press-fit holes but I still consider that price awesome. If you use them keep in mind they don’t handle credit cards, just cash.

Okay, so now the wheels are holding up the start of frame re-assembly. And what’s holding up wheel assembly? Rim restoration. If you follow this blog you know I spent some time (heh, he calls days and days “some” time) on one rim and it wasn’t done. Of course I learned since then, right?

Here’s the second rim after going over it with 60 grit sandpaper. You heard right. 60 grit. That cut through the corrosion and took the surface down to the bottom of the pits in no time.


That was about two hours work. And 60 grit leads to 120 grit —


This took another two hours or more. Getting the spoke nipples and rounded surface evenly sanded is tough. And as I lower the grit it seems to take more time to get the job done. Well, not done yet. Here’s after 320 grit —


Maybe three more hours. Now onto the polishing wheel with black emery compound. This cuts through 320-to-400 grit scuffing pretty well. I’m not finished as I write this and I’ve got, oh, maybe three hours on the polishing wheel so far. I figure I’ve got another hour on this rim until I switch to Mother’s Powerball polish (two more hours?). And I need another couple of hours on the other rim. I was all pumped to get the rims done this weekend (some of those photos were mid-week evenings) but it was not to be.

I’ve even got tires and inner tubes. I could not locate most of the tires recommended in the FAQ files at “5 United,” not at Southwest Moto Tires nor at American Motorcycle Tire. Some of them are just no longer available. This bike’s sizes are not popular (19×3.25″, 18×4″) and the inch-sizes are more accurately fitted than metric equivalents. The rear tire can be finicky to fit because it is a tight spot getting past the swingarm. A spacer can be used to allow a larger tire but I am not planning that. I ended up with Metzeler Lasertecs. They look great but I can’t find one word from other owners about ’em. The Metzeler inner tubes are scary only because they fit a wide range of sizes. The full set of tires and tubes cost about $250 at AMT. Ouch! What do I know about tubes? Not much. But buy a name brand and mount them carefully, to avoid pinching, because a blow-out can be fearsome with tube tires (worse than tubeless blow-outs). I’m going to trust Buchanan to do everything right when they assemble the wheels.

I may also need to deal with the wear on the rear hub’s drive teeth before assembling that wheel, easier to ship just a hub.

I solved my compressor complaint. Serious compressors need serious energy so 220 V is commonly used to reduce the current requirements. I have not run any 220 V in my garage so for the moment I’m stuck using a dedicated 115 Volt 20 Amp tool circuit I installed during our recent home improvement binge. That means somewhere around 2 HP true continuous motor rating, including start-up surge. Bob, who has a 220 V compressor, told me no matter how big a compressor is you’ll probably find uses that exceed its output. I did my usual obsessive research and got the most compressor I could handle.


I was slightly worried because several reviewers say it tripped their 20 A breakers. I had no trouble. Sears even had a 5% off sale on this just in time for me. It weighs about 150 lbs so I could muscle it around by myself to unload and assemble. Second choice would have been a DeWalt (Emglo) oiless compressor at Home Depot at virtually the same price. But oiless is louder and I don’t believe they last as long as properly maintained oil compressors. This Sears model is one of the few compressors I’ve heard that doesn’t sound like a monkey getting hit with a cattle prod. They claim 78 dB noise. My ear isn’t calibrated but you can have a conversation in the garage when it runs and I don’t feel a strong urge to wear ear muffs around it. If you get something similar, do the break-in procedure (in this case unloaded running, no pressure, for 20 minutes). It seems some folks don’t read the manual, never break-in the cylinder(s) or properly fill with oil, and don’t get best performance and life.

Sears claims flow is 6.8 cfm at 90 PSI. Seems about right. I was able to run my bead blaster’s smallest orifice at 80 PSI essentially constantly. I run out of beads, needing to tilt the box to pile up the beads, before I run out of air. Compressor duty cycle (“on” time) feels like 75% or so.

Sunday was time for more Homo Two-Wheelis! I haven’t reported on a club ride in a while because, well, we didn’t have any for a month. Today was the 3rd or 4th annual Ride For Guides, a benefit ride for Guide Dogs of America. BMW Joe and I went on this one for two or three years now. Yeah, I can’t remember shit. Sue me. This is a great charity. They estimate it now costs $38K to provide a single trained guide dog per recipient. I forgot my camera so you have to suffer with pictures from my lame camera-phone.


This is at the start in Sylmar, with large groups already on the road. I could not believe today’s turnout! Participation was over 400 riders this year. They ran out of food (bought more) and seats at the end but we had a good time. Gary didn’t join us. He’s on a five day ride up to the Superbike races at Infineon Raceway in Sonoma with Italian joe and other friends. So I cannot tell you the temperature (one reason we like Gary’s Hondas). BMW Joe almost didn’t go on the Guide Dog ride with me, he was ill earlier in the week. The ride was from their Sylmar site, up to Newcomb’s Ranch on Angeles Crest Highway (check point), and back through Upper Big Tujunga and Angeles Forest Road (another checkpoint at a cafe here). Here’s a crappy pic of Newcomb’s Ranch.


I have never seen it so crowded as it was today. The bikes continued up the hill behind me, even though most of the Guide Dog riders were travelling in smaller groups. Weather was nice and the roads were clean. I guess that’s enough reason.

Did I ever tell you BMW Joe is lucky when it comes to raffles and such on these rides? Well he is. This particular ride has the best prizes donated to raffle off of any ride I can think of. Last year his wife Mary came with us to this ride and out of fourty prizes Joe won three! He didn’t buy more tickets than average. Anyway, I’ve got a picture somewhere of him bungee cording a DVD player behind Mary. This year we had about the same number of prizes, including an Ipod, a decent digital camera, and plenty of Harley goodies (like a new seat!). Despite having 400+ riders in the raffle once again Joe won a prize. This year I took it home in my Givi top case since my FJR is still rolling in “dreadnaught” mode. I’m holding it hostage so he’ll come over and take a look at some parts.

In case you care, on the poker hand I drew a pair of jacks. I think I beat Joe but you won’t believe the top three hands. Even with 400+ people playing it is rare to see five aces. Yow, that’s some significant blind luck! And the number two hand? Five kings. Can you imagine drawing five kings and coming in second? That’s what we poker players call a painful “bad beat.” That’d sting. Third place drew a royal flush. Ho hum, just enough for third place.

I’m clean now and Julie says I can’t go back into the garage tonight. So, time to hydrate some more. See you next week.



  1. we always use air compressors in spray painting and also in blowing off those hardened dust on our home,.`

    Comment by Chrome Towel Radiator : — October 26, 2010 @ 10:40 am

  2. the air compressors that we use at home are the high powered ones, we also use it for cleaning .;~

    Comment by Sectional Garage · — November 12, 2010 @ 1:15 pm

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