Airheads, snowflakes and safety checks
I’ve been subscribing to Motorcycle Classics for several years since I found it, and enjoy it as much for its ability to let me relive my younger years as for its entertaining and informative content.
Most of my friends and I all were starting trades that paid well enough that we all (about twelve of us except for a Norton die-hard) bought new /6, and /7 Airheads, mostly R90Ss and R90/6s when they were introduced in 1974, through the last 100/7s before the significant changes in 1980. They were as “long haul” fast as anything other than Laverdas and Ducatis, but had big gas tanks, long touring range, and WATERPROOF Krauser luggage! We put six-figure miles on them, and most of us still have at least one. Several of us worked for Rose City BMW, the local dealer, and all of us had close contact with them, and another regional dealer, Hansen’s MC in Medford Oregon. I had many conversations with Craig Hansen, and as I was the service manager for a BMW car dealer, he and I traded information, including Technical Service Bulletins.
I noticed a comment in the BMW Airhead feature of the September/October issue that I believe needs to be addressed as a serious safety issue.
The factory cast wheels installed beginning on the 1977 BMW /7s would hold air when mounted tubeless and many of us did that. That was until the factory made the unequivocal admonition that those “snowflake” wheels should never be mounted tubeless, because the wheels did not have the proper rim design to prevent a catastrophic deflation of a tubeless tire if the rider hit an obstacle with force. I know the BMW factory eventually introduced wheels that were intended for tubeless fitment but I can’t offer any insight in that regard. I also remember a recall regarding the Fuchs front wheels in that era, the area holding wheel bearings was mis-machined, but I believe most bikes were retrofitted, wheels scrapped and all should be well.
And as a nitpick; the long driveshaft/swingarm with the longer subframe was introduced in the 1973 /5s and allowed for a bigger battery too.
Thanks for your consideration, and keep up the good work on the magazine.
Scott Whitcomb, Sherwood, Oregon
Thanks for this important cautionary technical note. Other than possible porosity, cast wheels might seem OK for tubeless tire use, but it’s not always the case. Perhaps in a future How-To column, we can bring in a wheel/tire expert to clarify differences.
— Ed
Powder coating?
Greetings, and this was inspired by Backus’ recent piece mentioning a frame powder coating. I’m no (actual) purist, but my sources say “Do not powder coat.” It’s not easy to retouch and, well, it just ain’t “original.”
Like Backus mentioned, I also seem to sputter and sometimes “crash” a bit in my maintenance and restoration work. Current project, albeit in slow motion, is a ’69 Ducati 350 café build. Other pieces include a ’69 Victor, long-dormant, and an ’87 K75S, on the road but seldom ridden, a ’72 CL 350 in good rig, but yet to be ridden this year.
Howard Bartle, Sterling, New York
Though I’m not totally up on latest in powder coating, for reasons of getting a true black color for frames, swingarms, triple trees, etc. I stick with single stage paint. If you mix powder coated and painted black detail parts on a bike, they may differ in their black hue in direct sunlight. Most of the major suppliers still offer such a single stage paint product, PPG Delfleet Essential being one. Avoiding powdercoat and clearcoat makes the grain of castings and stamped serial numbers show in a more factory-original way, and you avoid the “wet look.” And as you say, true paint can be touched up. I also prefer a milder approach to prepping parts for a finish; most powdercoating shops sandblast parts which can remove detail, erode rivets and serial numbers and even warp sheet metal.
— Ed
