You Want To See Big Machining?

I take it the motorcycle is a Tricycle model at least!

Martin [ Thought it was a mine pump :-) ]

Sure, sure. Just where are you going to get and put the gear box.? Never mind that it will have to be geared up.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs

A friend of mine did some calculations with respect to a single cylinder English bike once, a Vincent I think. He figured that at top speed the cylinder fired every 50 feet.

He'd better re-check his calculations.

At 60 miles per hour - a mile a minute - firing every 50 feet would be about

100 times per mile, which for a four-stroke would be 200 RPM.

Even every 5 feet would probably be on the high side. Every 2 feet might be more like it.

John Martin

and here I thought the tomahawk was crazy

Speed has nothing to do with it. As long as it is in the same gear, the interval will be the same.

All the Vincents I've seen were V-twins.

Ted

Those were Black Shadows, Black Lightnings and (maybe if you were lucky) Black Princes. The single cylinder models were called Comets.

500 cc. Think a twin crankcase with a single cylinder. There were, IIRC, A, B and C model Comets to match the Shadows and Lightnings (the Lightning was essentially a tricked up Shadow). There were no D model Comets to match the Princes.

The Comet was not as desirable in the US and not as fast. But Vincents were also popular as sidecar hacks in Britain. The Comet still had gobs of torque and reasonable top speed for sidecar work.

--RC Projects expand to fill the clamps available -- plus 20 percent

A friend of mine in the UK describes the time he bought one of those 50 cc, eighteen-gear, six-valve racing bikes that used to be popular over there, and decided to see what it would actually do on the local motorway. He ran it up through the gears and then stretched out on his stomach on the seat to get the maximum streamlining. There he was, stretched out perfectly prone with his toes pointed out the back, waiting for the speed to creep up to 80 mph or so, engine screaming at near ultrasonic speeds, when he was suddenly passed by a big Vincent being driven by a old guy in a tweed jacket and deerstalker hat, sitting bolt upright smoking a pipe. The guy just glanced over at him curiously and continued on his way. My friend was so embarrassed that he got back up, turned off at the next exit and went home. He sold the bike a few weeks later.

-- Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love America

There is no subsititute for cubic inches -- at least up to a certain point.

The Vincent is not a machine I'd recommend to anyone except as a collectors item. Mr. Vincent didn't believe in things like frames and putting even a Black Shadow hard over into a corner is a truly religious experience -- do it and you will See Jesus! But they are beautiful and for their day they were tremendously fast bikes.

--RC

Projects expand to fill the clamps available -- plus 20 percent

My friend who advanced the 'cylinder firing every 50 feet' calculation that John Martin didn't buy (perhaps it was hyperbole) also recounted the following story.

A Vincent owner allowed a friend to take his Vincent out for a couple of laps around the track. "Be careful," he cautioned, "it corners like it's got a hinge in the middle!"

The friend returned after one lap to report, "That's not a hinge, it's a balljoint!"

Your friend was probably closer to the truth. In a Vincent the forks bolt to the oil tank under the gas tank. The oil tank in turn is bolted to the engine. The engine is bolted to the rear wheel and the rear wheel is also attached to the back of the oil tank by a couple of shock absorber thingies.

Technically that may be a hinge, but it could sure move like a ball joint.

--RC

Projects expand to fill the clamps available -- plus 20 percent

Bully for the Guy in the Tweed. Played his part to a T. Your friend so it would seem was trying to transcend into someone he wasn't and realized.

Martin

That would be pretty slow.

Now the turbines on a SSME have about the same shaft BHP, and have a power-to-weight ratio over 2,000 times better - far more suited to a mobike :)

BTW, from that link:

" The top of the connecting rod is not attached directly to the piston.  The top of the connecting rod attaches to a "crosshead" which rides in guide channels.  A long piston rod then connects the crosshead to the piston.     I assume this is done so the the sideways forces produced by the connecting rod are absorbed by the crosshead and not by the piston.  Those sideways forces are what makes the cylinders in an auto engine get oval-shaped over time."

That's maybe a small part of it, but the real reason is that the stroke is about three times the bore (needed to make it so efficient), and conrods of any reasonable length would have to somehow occupy the same space as the cylinders if a crosshead was not used.

(just been desiging compressors, and had the same need for a crosshead-ish arrangement on the hp cylinders, with large stroke/bore ratios. They used to do the same thing on triple expansion steam engines.)

Without the crosshead and attendant piston rod the engine as a design would fail to function. As it is a two stroke where the intake air is admitted under the piston and sealed by a gland on the piston rod from the crankcase, a crosshead is mandatory and normal practice on large diesel engines.

Tom