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Yamaha (Y)Z608 TD1A hybrid

Published Date

Warren Warner found a very interesting old Yamaha race bike and asked me some questions.

In order not to change the conversation too much, here is what we talked over so far:

Warren: "I am contacting you concerning a Yamaha TD1A/R1 racer as acquired from John Buckner, good friends with Tony Murphy during his racing career. The TD1A has a heavily modified R1 350 motor, and I am curious if it, or some performance bits, could be related to the RD56/R1 hybrid (Y) Z608 of Tony Murphy. The R1 motor (engine number R1-0077) was mated to John's TD1 sometime in 1968 or early 1969; probably an off season project. The bike was ridden and wrecked during the 1969 season, was dismantled, and has remained largely untouched for the past 40 years".

(What a dream to find a racing bike like this!)

yamaha yz608/td1 in crate

"The stock TD1A motor may have been part of the engine deal, as it went missing about the same time".

yamaha yz608/td1 l.h. side

(Tony Murphy was one of the main Yamaha riders in the USA in those fantastic mid 1960 years)

I answered: "I am very happy with all the very interesting questions I get (and many come from the US). The problem with questions like this is that the American race scene differed so much from the European. Only when Kenny-San crossed the Atlantic things started to change. By the way, on his first visit to Holland in 1974 I picked him up from Amsterdam airport and cooked him ham and eggs!

But coming back to your engine.

YMUS made these 6 bikes by themselves and asked Yamaha Japan for help. These experimental bikes were crafted together from mainly factory RD56 frames and wheels and standard/tuned YR1 parts.

Hence the near standard engines with a 4-speed gearbox (AMA rules, otherwise the competition with H.D. was unfair….). The first gear was removed and a 4.9:1 top gear was used. You can check this on your engine easily. The engines also used sometimes 2 cylinder head gaskets.

Yamaha made chrome bore cylinders like on the TD1B (at that time), supplied AMAL type 30 mm carburettors (with separate float chambers) and some experimental electronic ignition. The rest you know.

As it was not immediately a full Yamaha project the engines had normal production numbers and I cannot imagine they were recorded by someone. It was simply not important at that time for the factory".

Your cylinders have the exhaust nuts as later on used on the TR2/TR3 machines so I am pretty sure this is definitively one of the 4 US bikes. (2 machines went to Japan, where one was ridden by K.Mimuro to 3rd place in the Japanese GP behind Mike Hailwood and Ralph Bryans on Honda's (what else).

For the 1968 season Yamaha "coded" the racer YZ608, but the specification also indicated that it had modern Mikuni VM34SC carburettors instead of the old AMAL types.

yamaha yz608/td1 carburettors

But it seems strange to me that this powerful motor was fitted into such a bad frame.

Because everyone in the USA knew that TD1A frames were made out of bamboo!

As the construction was carried out in 1968 a late TD1B frame (or early TD1C) would have been a much better proposition. But that is the fog of history! Having said that, you can see that Buckner's machine is already fitted with an alloy top yoke from a TD1C instead of the very thin and fragile steel plate item from the TD1A/B.

yamaha yz608-td1 r.h. side

Warren: "I will have to allow the penetrating oil a little time to work it's magic in the engine before checking the final gear ratio; it turns, but not without an argument. A fellow TZ owner in Whitehorse, Yukon has also just sent me the contact information for a gentleman who supposedly knows the owner of the Suzuki powered Z608. It is somewhere in the Vancouver BC area as he recollects. I will be following up on that lead next.

The tale of the R1 powered TD1A bears your observation to fact. John Buckner's dad Leo was the builder for John, and performed the conversion. I suspect the most likely bike for him to modify was the TD1A model, as the TD1B was his most successful and competitive bike, and the TD1C was likely too new to cut up. Much time was spent on bracing and reinforcing the TD1A for the motor swap. While John was campaigning the TD1B overseas, Tony Murphy was racing John's TD1C on the popular West coast/California circuit - it was during this time that the A project began. John crashed the TDR1A hard during the 1969 season here in the U.S., and was severely and permanently injured; he is still in a wheel chair from the accident.
During our last conversation, John mentioned the dealings and adventures between Tony and himself; John was a helicopter pilot back then (he was the pilot for the CBS News team - major TV network here in the US), and would fly to the various tracks and race the bikes his dad transported by truck. That way he could subsidize racing while working, which allowed him to climb the ranks. The TD1B was his favourite ride, but it quickly was becoming obsolete, that is most likely the reason he was testing the 350 bike.  He severely underestimated the performance of the R1 motor, and the rest is history.

Here is a picture of the frame and another shot of the motor.

yamaha yz608/td1 cycle parts

It came with spare top end, crank, and I found the missing head; I need to search the box of ignitions again to try and see if anything fits - I will have to clean it up a little too I think...

yamaha yz608/td1 engine

I did have the opportunity to dismantle much of the R1 motor, and do some investigative inspection. Here is a summary of my discoveries:

yamaha yz608/td1 magneto

I located the Magneto; it is very similar to the TR2 item, with one main difference; the ignition coils are mounted under the long side of the main breaker/mounting plate. On all other photos of assemblies found for the 350cc magnetos, the coils and/or condensers are in reverse positions. The Magneto is marked "M-X19 70201." The assembly obviously spent much time at the bottom of a parts box judging by the condition of the points, but the coils and wiring below the outer plate look fine.

Under the clutch cover was a very pleasant surprise; the internals looked quite fresh, and very clean. The primary ratio is 2.96; crank/clutch gear tooth count is 25/74. Primary gears are straight cut, and the clutch basket has a riveted steel band reinforcement around the ears, much like the TZ750; there are 7 fibre plates.

yamaha yz608/td1 clutch

The internal gearbox ratio of top gear is .82 (same as the TR2), but the final gearing/sprocket combination used is unknown so I cannot calculate the final overall ratio. It is a 5-speed gearbox, but could have been converted for non-AMA Daytona events. I understand the 4 speed rule was changed in '68 or '69? The shift shaft linkage has been modified with brazing work done on the change shaft stop.

yamaha yz608.td1 cylinder

Sadly, the cylinder with the head removed suffered water damage, and the crank mains are rusted solid. The connecting rods is fine, and it looks like water was channelled down the main lubrication casting holes directly into the bearings. There was only one head gasket installed on the good cylinder, and the compressed copper gasket measures 1.2mm. Notable detonation damage is evident on both heads.

I talked to Tony Murphy about the Z608 bikes (he owns and runs a Rotax performance shop in California), and he passed along some interesting information. Seems as though Yamaha tried to collect as many of the RD56 chassis as they could, but were not so interested in the spare engines that were supplied with the bikes. Tony thought that the Motor John Buckner had was one of the extras, and same for the spare cylinders. I think we have a winner here! I am going to pick up the TD2 chassis next week, and then the project begins.

I believe I have solved the origin question of the R1/Z608 motor, and it was thanks to you and! Your pictures of the June 1967 Cycle World pages held the answer. I could not get much detail from the scans on your site, so after a month long search, was finally able to obtain the actual magazine to examine. Mostly the pictures of the right side of the motor & bike held the secret.

When the magazine arrived, I stared at the article and pictures for several hours before the pieces started to fall into place. I noticed that the picture of the motor showed that the outer clutch linkage cover had been shortened for access to the adjuster. I remembered that my R1 also had a shortened cover. I pulled out the cover, and was immediately disheartened as the cover had obviously been hack sawed, and was not a smooth cut like I envisioned the original to be (as done by the Builder/Yamaha). When I brought it in to do a direct comparison with the article, to my surprise and delight found the picture in the article had the identical hacks awed and crooked cut! Also, the fairing polishes matched the cover; it is the same one :-)

yamaha yz608/td1 clutch cover

Next I pulled the right cylinder, and found the bad sag in the article picture of the third cooling fin (same photo) again matched what was on the R1. About this time I was starting to get excited, and went after all the parts I could compare with in the pictures.

I found I also have the expansion chambers from the article bike; there is a distinctive repair/removed dent mid-body on the right pipe, and again quite exactly matches the photo! The tiny reinforcing welds where the last reducer meets the stingers are there, and the configuration, shape and mounts are also a match.

I am now 90% convinced that not only is the R1 a genuine Z608 motor, it is the actual motor from Tony Murphy's Cycle World bike. I am sending along a picture of the right side outer cover and the barrel; if you have the magazine to compare with, please have a look.

cycle world yz608 testcycle world yz608 test














So far, you are the only person (other than the people I asked to evaluate the parts and pictures) I have shared this info with.

I would be honoured to keep you informed of progress and give credit for your generous help; had it not been for your guidance and postings on your web site, the discovery probably would have never materialized. I have also decided to build a 1/2 genuine/replica of the Z608/RD56, and even though it will take substantial time, effort and finances, the bike and build will truly be the centre piece of my very humble collection. A friend of mine had already offered to donate a bare TR frame, so it looks like the project has begun; this is very exciting

I did find the #112 article - thank you! Very typical of 1960's USA bike magazines with only part of the info they probably had; careful with what is said about advertisers information you know...

I have had a great success with starting the Z608 project; last Friday I acquired an early TR2 (#TR2-900112) frame.

yamaha tr2 frame number

There is a side stand boss welded on plus a few extra tabs for an RD motor, but all the original bits appear intact and should be quite easy to bring back to spec.

yamaha tr2 frame

Please feel free to pass on any information as you like about the bike from here on (your good judgement was much appreciated), as I will be going ahead with the restoration. It will be a major undertaking, but now that I have a very authentic frame, I know the direction to proceed; I am going to build the Daytona bike with the YR1 front end as close to the Cycle Magazine pictures as possible. The old YR bikes can be found here, and the front end should be easy to replicate with minimal cost.

The brakes will be the tough part, but depending on what I find first, a period Grimeca or Fontana Double TLS will probably find its way to the end of the forks. A few modifications will be necessary to come up with a reasonably authentic looking copy of the RD56 stopper; shave off the air scoop and mock-up a false arrangement. I thought of using the TD/TR item, but it would be a shame to alter an original unit. The rear will be less crucial, but the search is on for a swing arm - sadly the one on my TR frame was sold long ago.

I have not decided how to proceed with the body work. I may look for a TD/TR tank, and modify the shape, cap and breather configuration, and lower tank box. The nose on the "3" tank is closer, but the 2 tank would probably fit the frame more accurately. Do you know of a tank builder that has already constructed one? I am sure I can copy the tail section with glass fibre if need be, and the drive train is basically complete!

I will keep you posted on progress (slow progress I am sure), and would appreciate any suggestions since I understand you have already been down this path. I will be building a runner, and plan on having the barrels Nikasiled and building a fresh crank; the gearbox and clutch looks almost new. There is no case damage, and excluding the timing side cover, the drive train is complete.

I have a YR1 front fork assembly now, in very good original condition and a bargain price at $65 USD. It is complete including the stem, shrouds and crown - A quick rebuild and freshen the paint is all that is required; the chrome is still good.

I just returned from the National Antique Motorcycle Owners meet, and was able to find several more articles and pictures of John Buckner,

John Buckner, the original owner/rider of the machine in this story

john buckner

Tony Murphy and his TD1's, but no additional info on 608's. There was also a short article and photo verifying one of the stories John had told me: He was at the Willow Springs Raceway in California in 1966, and raced his CBS helicopter against a TD1. There is a small photo of him in the 'copter and the TD1 about to begin the competition. The Yamaha won, largely due to the corning abilities of the cycle - he is a very colorful guy.

I will try to get some good pictures of the magazines - he and Murphy are on the cover.

Best regards, Warren Warner

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