Shadetree Enterprises Norton Dom 99 / 750 circa 1971
This Motorcycle derived from a thorough overhaul and general component upgrade of the PM Norton, with which Rich Arians achieved the AFM Number One plate in 1964. Just about all that remained carried over were the frame, fuel tank, seat and some fork components; perhaps some gearbox pieces. It got a bigger engine, from a wrecked P-11.
This bike was ridden in California AFM and AMA events by George Miller, Bill Judkins and Tom Davenport from 1969 to 73. Although it was very fast and was really a kick to ride, reliability problems relegated it to a lot of DNF's and also rans.
The P-11 motor ran 10.5:1 Powermax solid skirt pistons which had a lot of contouring done to clear the valves, as the cyl. head was minus .090" and the Megacycle cam (based on the PM cam from the PM Dom 99 motor) not only had substantial lift, but also passed the valves very close to each other and the pistons. Valve to Piston clearance was checked using clay on the piston surface; valve to valve clearance was checked by inserting a piece of .125" copper wire between the valves, turning the motor over very carefully, and checking how thick the wire was after removal!
There are a number of unusual and "unique" features; perhaps "most unique" are the Yoshimura slow taper megaphones, which were purportedly formed around a baseball bat! The megaphone profile, as well as the long inlet tract length, favored keeping the machine tractable at low to medium engine speeds; it turned out that, being a Norton, this was help it didn't really need, as it ran
strongly from around 3,000 R's and always continued to do so even with more radical plumbing it acquired later on.
In those days, Yoshimura components were "imported" from Japan by Air Force personnel, who brought them in along with their personal effects when coming stateside, according to the late Larry Shively, organizer of the first AMA Pro level racing efforts in the U.S. under the Yoshimura banner (1971).
A difficult detail to see, just ahead of the clutch, is a Manx Norton legacy item, a Primary Chain Oiler! We've heard rumors these are no longer popular, even at vintage bike races. Also please note the highly security conscious super-sturdy garage door and lock hasps! You can also see that we new how to use 200 mile-an-hour tape for custom upholstery.
This bikes least endearing quality was how fast you had to push it to start it up. It turned out you could actually kick start these motors, even with locked advance ignition timing, but that only works if you have a kickstarter! This machine arrived at AFM races at about the time when live engine starts began; prior to that, the English and European practice of "run and bump" had been the order of the day.
As seen here, a Fontana 180mm four leading shoe front brake with Ferodo Green linings is used. Norton Roadholders with two-way damping valves and external progressive wound springs. Exhaust pipes were fabricated from U-bends purchased from a muffler shop. The alloy 5/16" thick scatter shield above the clutch and primary chain was retained from the PM Norton; it is probably a hold-over from Kibblewhite's drag racing days in the late 50's! The idea was for the chain to go away from the rider and not pack up the clutch (which stops the rear wheel from rotating) if it spit a primary chain. This motor sported 1 5/16" AMAL GP carburetors, a pair of which (left and right hand) were made as a one-off set for someone else's project, and ended up on this one. They caused a lot of trouble, primarily because of the engine vibrating in quite a different way than the single cylinder Manx Nortons and G-50 Matchless' their remote float chamber shock mounts were designed to handle.

The bikini fairing was Bultaco Metralla, sort of a convenient place to hang a number! George Miller is aboard, at Willow Springs in 1972; the pit photo is at Ontario Motor Speedway, also 1972, and shows some significant modifications a sharp eyed viewer will be able to spot. The fairing was fabricated by Bruce Haugh, and is basically the same pattern as the Yamaha 350 in the background (which, by the way, carried the AFM Number One plate in the 1973 season)..

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