WL. Why a Ducati Diana?

When I started road racing in 1973 I chose to race a 1960-something Ducati Diana in the 250 Production class. I mention in the book “Racing the Gods” that selecting a 6 year old bike was an odd choice. It would have been a good choice in, say, 1968, but this was 1973. In the book I do not explain why I chose the Diana. I’ll explain why here.

I had two main goals when I started racing. One was to ride fast in a safer environment than the street. I wasn’t going racing the win, although I didn’t mind competing. The second goal was to learn wrenching skills. I planned to do all the work on the bike myself, and thus learn some mechanical skills. I had spent a little time helping my dad rebuild a straight-six engine in a 1953 Plymouth so I wasn’t a complete novice. I wanted to race in one of the small production classes, 250cc or 200cc, and it had to be a used bike. I had been working full-time for only a little more than a year and I didn’t have a lot of discretionary income.

I didn’t like two-strokes. It’s a little embarrassing to admit, but I didn’t understand how they worked back then and I didn’t like the noises they made. That eliminated all the Japanese bikes except Honda. The CB175 (in the 200cc class) or the older 250cc CB72 (in the 250cc class) were possibilities, but both had an overhead cam run by a chain from the center of the crankshaft. The cam chain had no master link so to take the top end off you had to break the chain then re-rivet it when you put the motor back together. I had never done that and wasn’t confident I could do it correctly, and I knew what sort of expensive damage would result when the cam chain broke.

That left only OHV bikes (i.e. push-rods) or gear-driven overhead cams. There were some British OHV machines around, and some had successfully raced the Harley Davidson Sprint 250 (which was actually a re-branded Aermacchi). However, from reading old magazines, the gear-driven overhead cam machines of Ducati were most competitive. And, you could take the head and cylinder off to work on the bike without needing to break a chain. I started looking for one of those.

I found a Ducati Diana for sale in the fall of 1972. It was dirty and very worn on the outside but all the parts were there and it ran. I bought it and looked forward to opening it up and seeing what it needed. The first tear down was pretty interesting. The inside of the bike matched the outside – it was very worn and dirty. The rings were shot and there was a lot of carbon crusted on the head, the piston, and the exhaust valve. I had fun during the winter of 1972-1973 tearing the bike apart, inspecting everything and creating a shopping list of parts to buy.

Putting the motor back together was simple. All the cam drive gears were marked with an engraved dot. Just line up all the dots, put the head on, tighten four bolts and done. No worries about a chain breaking.

Me and the Diana at Sears Point, ready for my first ever race. I’m not a big guy; the Diana was a small bike, even for a 250cc motorcycle. Photo by Va.

And that, in a nutshell, is how I ended up racing a Ducati Diana in 1973.

I learned a lot about the Ducati motors from the old Diana, knowledge I applied to building my 350cc Desmo race bike. That effort is described on the page ZX. The Ducati 350 Desmo Racer.