Wednesday, July 7, 2010

1972 R5C AMA Homologation Special?

Bob writes in with a rather intriguing story:

i have a 1972 R5-C that was delivered new from Yamaha with a six speed transmission instead of the standard 5 speed. the dealer told me Yamaha made 200 of these with a six speed to qualify for AMA racing rules at the time. i have tried for years to get some kind of info or documentation about these 200 bikes but have not had any luck. I have been told by some that Yamaha never such a bike and the dealer probably just installed a TR3 six speed transmission in the bike at his shop. I suppose that is possible but i was there when he unloaded the bike new still in the crate from Yamaha and he told me then about the six speed transmission. He owned the bike for a short time then sold it to my best friend and I eventually ended up with the bike and have had it in my possession ever since. I was just wondering if you have ever heard of these 200 bikes with a six speed or know where i might be able to get some info on them... serial number is R5-111013 manufactured 12/71.

Very interesting. When asked about any distinguishing features, Bob sent the following:

i will get some pics but it looks identical to a standard RB-C except for the rubber rings around tach and speedo... here are photos of the tach rubber on the standard bike and the "six speed" bike. notice the tall front on the rubber on the "six speed" bike [above] compared to the standard bike [below]. Maybe some other Yamaha model has that shaped rubber? Oddly enough there is absolutely no difference in the rest of the bike.

I've seen other bikes that have been homologation specials of this era, and it does seem that 200 is the magic number in order to qualify for AMA racing. Anyone have any ideas, leads, or information about this particular run of homologated specials?


  1. Probably not what you want to hear but ... Having "participated" in AMA, AFM & ACA Roadracing of that era I would tell you that there never was a "factory produced" R5 with a 6spd gearbox. I would have know. Not just because I did have some minor dealings with Yamaha then but rather, If there had been a 6sped R5 in competition (on the track) I would have know about it. I guarantee it would not have gone un-noticed.

    The speedo/tach surrounds were a common swap when they became available, likewise the RD 6sped and front disc brake.

  2. Thanks for your response but I do know that this bike does NOT have an RD350 six speed trans as I rode this bike in early 1972 well before the RD350s were delivered. Also it has a close ratio 6speed trans, not the standard ratio trans that came later in the RD350. The only possible swap would have come from the factory Yamaha TR3 350 roadracer which DID have a 6speed trans in 1972 and since it is a close ratio 6speed i have always suspected that was the source. You also said the speedo/tach surrounds were a common swap, can you tell me what model they are from as I have not been able to find any Yamaha model with this slyle. Thanks for your help.