Tagged: Yetman

1965 Yetman framed Honda CB305

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Some of the greatest achievements that man have made came out of the garage. That guy with a beer in one hand and a wrench in the other is able to create something that changes the world, or some small part of it. This may be a huge reach, but this 1965 Honda CB305 with a Yetman racing frame is a bike that shows that a guy like David Yetman could create something to replace his broken bike.

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From David Yetman

In 1965, while working for Autodynamics, Inc., a builder of Formula Vee racing cars in Marblehead, Massachusetts, I had the misfortune of wrecking my new CB77 Honda Super Hawk by broadsiding a large sedan. Being unable to afford a new frame, I designed and built one using my race car chassis experience.  Autodynamics’ owner saw the eight-pound result as a commercial possibility and bought the rights from me.  When we had a falling-out some months later, I repurchased the rights and set up The Yetman Corporation with the financial backing of a friend.

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I have heard the term “Spaceframe” before and always just assumed it was a general term.

From David Yetman :” pure “spaceframe”, meaning that all of its structural members were triangulated, either in compression or tension. The design derived its strength from its form, not its material. ”

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When you are able to strengthen something with design, you can see were the weight starts to drop. Some more great reading from the man himself can be found here.

Now this bike up for auction was put together by a different guy, but the spirit is the same. He had an engine, a frame, and some other parts and started to put them all together. Now its you chance to take over from this seller with his Yetman frame.

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From the seller

This is a rare original nickel Yetman roadrace framed Honda 350 that I had started to convert to road use. It is highly modified and a work of art and goes like stink. Had it running last year around my neighborhood and just rips. It has the following:

Yetman frame with number 3015 stamped in it. Frame is beautiful work of art with great nickeling all over but has a wear spot near steering from cable rub and 3 small dings in top under seat location as shown in close-ups.

Engine is a CB72 lower end with serial number CB72E-40164. It has been highly modified with 305 barrels bored out to 350cc with a race cam, larger carburetors, and high compression pistons. This was info I was told when I purchased it and it goes like it is bigger than any 350 I have ever ridden. Plus the high degree of work done to the case covers and special clutch set-up indicate a lot of work was put into it.

Running constant loss ignition with no kick start so currently bump start. Was not too hard to do. Original Yetman gas tank with older cream coat. I put race fuel in so not a problem but if using newer fuels I would coat it again with something else. No leaks or cracks in tank.

Has some CYB parts including smooth fork crown, racing exhaust megaphones and I believe the rear sets.

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This 1965 Yetman framed Honda CB305 is a project. You are going to need some work and money to get this bike on the road. I think what you have at the end of the journey is going to be something very unique. BB

 

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Is it a Yetman Honda or Honda MT125R

Two bikes offered for sale here confused me. I started writing while looking at a full fairing bike labeled as a Yetman Framed Honda and I wondered why the exhaust poking out from under the fairing was so thick? I then started to write something up on the MT125R listed by the same seller. I thought that there was to much going on above the  intake and exhaust to be a 2 Stroke.

After talking it over with my co-horts and digging into the RareSportsBikesForSale archives, we have come to the conclusion that the seller swapped pictures, so I will hopefully correct this for them here at Classic Sports Bikes For Sale.

1966 Yetman Honda 305

Who hasn’t borrowed stuff from work? An envelope here, some paper there, low carbon cold-drawn steel tubing. This is how Yetman frames seem to have started. David Yetman recounts his history at TZ350.net and tells of having wrecked his CB77 was unable to buy a new frame. He decided to use his day job with Autodynamics, Inc, builder of Formula Vee race cars, to solve his problems.

            This excellent example has a highly modified Honda 305cc engine, engine was enlarged to 350cc with a race cam, larger carburetors, and high compression pistons. The transmission has been “X” -ed which was a common technique at the time to get closer gear ratios without having to spend the money on a 5 speed transmission.

David took his race car chassis experience and developed his frame with all its structural members triangulated either in compression or tension. This, with the engine incorporated as a structural member, allowed the overall strength to increase and weight to decrees. The perfect recipe for a winning race bike. Yetman continued to make frames for road racing and later drag racing. Yetman frames have been designed for engines offered by Honda, Ducati, Triumph and Harley Davidson.

This Honda appears to be ready for vintage racing. The seller doesn’t tell where the engine was sourced, but the CB77 Dream Super Sport came with a 305cc engine from 1961-1967. The same bike that started Yetman frames.

The bike included many Honda CYB factory race parts such as the fork triple clamp and the megaphone exhaust pipes. Other special features are the alloy rims, fiberglass tank and seat, Koni adjustable shock absorbers, and the Ceriani road race forks.

1977 MT125R

 Mike wrote about another MT125R for RSBFS and gives some great background. The seller jumps right in to tell us about the bike.

The Honda MT125R was produced for the U.S. market in the years 1977–1978. It was a production Grand Prix motorcycle racing road racer designed for closed-course competition road racing. The MT125R was produced by Honda Racing Service Center (RSC) and made available to the general public through the American Honda Motorcycle dealer network.

Recycling many parts from Honda’s own dual-sport Elsinore, they were able win on the road with small changes. Adding a larger 34mm Mikumi and moving the whole carburater closer to the engine shortened the intake track and moved the power peak higher in the rpm range. The porting configuration and timing are the same, but a change in the exhaust pipe raises and narrows the power band. A first hand account written for Cycle World, tells of the difficulty in getting the bike moving, but once “on the pipe” the six speeds keep the bike in the power band.

Engine – 123cc 2-stroke air-cooled single cylinder, 6-speed, power 26HP
Chassis – fiberglass tank, fairing, fender and seat cowl
Other – tachometer, mechanical front disk brake, and rear cable operated drum brake

We always like lots of pictures to get the best idea of the condition of the bike. The only pictures provide for both bikes show nice bikes, but when ever buying from a distance, call the vendor and if you are able to, send someone you know and trust to take a look. Especially if the seller mixes up the pictures.

BB