Streets of San Antonio

The R90S:

If this were TV? I could get the image from a cell phone camera, blow up the dial gauges, read the actual mileage indicated. I’m guessing that they are original. The seat cover isn’t, and the gas tank was painted black, which would lead me to suspect that it wasn’t original or it had been dented and repaired.

It’s about a 1974 R90S, the original smoke color, at least, the seat badge is. Had the rounded valve covers, too, which changed in later years. Point of pride and trivia? The older, like this one, rounded valve covers actually provided a few millimeters more of ground clearance when leaned “way over” in a corner. The factory side stand would drag before the cylinders would.

Airplane motor. No, seriously.

The valve covers are one piece of the puzzle, another is the gas cap, which was changed for a different style in later years – a style less likely to emasculate. On that bike, the handlebars, and I’m guessing, throttle and brake cables, aren’t standard. The shocks appear to be stock, which is a shame as that’s one of the easiest ways to help with the behemoth shaft drive.

I knew all the tricks at one time, and that’s a singular piece of “iron” – another misnomer as the bike frame is high carbon steel while the twin front disk brakes are the only pure iron, and the rest of the motor should be aluminum alloy.

Burned up a crankshaft in one motor, turned an engine block into a very expensive souvenir. Dropped a valve in one motor, turned expensive cylinder head into a very strange relic. Carried that around with my household belongings for years.

Looked like there was an “American” rear end (rear gear ratio), a 32/10, or a 320, which was good for drag racing and one short circuit, a short road course, but no, not much good on the top end. Motor that size, almost a liter, had to wrap it too tight. The 1974, if I recall rightly, had the smaller bolts holding the flywheel on – more likely to shear off.

That was about the time machines ceased to have soul, after that model. About the time style and substance became marketing. That bike, on the mean streets of San Antonio? That’s one of the few pieces of hardware that still exhibits soul. With a touch of Teutonic class.

Airplane Motors Forever.

Just a silly notion. and its family of websites participate in affiliate programs, which means there are material connections between the ads, and this site. for appearances —
See the fineprint for full disclosure and terms.

© 1994 – 2021 Kramer Wetzel for

Comments on this entry are closed.

  • Scott Aug 8, 2009 @ 7:28

    You know bikes? Wanna come take a look at my 68 Triumph?

  • Kramer Aug 8, 2009 @ 11:09

    68 Triumph, twin? Single Carb, should slap a set – pair – of Del-Orto’s on it, 36 mm, if I recall. English “iron,” eventually…

    Never mind. I’m too old and it’s too loud.

    I like your truck projects. I don’t know where to find premium gas with lead for the valve stems, though. Unless, you think av-gas would work? There are two air force bases in SA… you’d think a pilot buddy could walk out with a little av-gas.

  • Scott Aug 9, 2009 @ 5:55

    Ummmm…sure, if you say so (about the Triumph.) I traded the 78 Big 10 for it. Won’t start. I got a Chilton manual for it, though.

Next post:

Previous post: