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TOPIC: Wanted.......Yamaha OU72/OW72 750 Information

Wanted.......Yamaha OU72/OW72 750 Information 31 Oct 2012 02:02 #180983

  • MDFlat4
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I'm,looking for more information about Roberts & Yamaha's OW72 project. I have all the information that has been printed or published. I'm curious exactly how many of the heads were produced. I've read possibly between 40-50...? An exact number would be great. I would also like to know which casting numbers went to who or were used for and by who. I would like to get in contact with persons that may have been involved in the project or guys that have built or run one of these engines. Thanks Curtis Fisk
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Wanted.......Yamaha OU72/OW72 750 Information 31 Oct 2012 03:00 #180985

  • Old59R
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Tom Horton is probably the most informed about these. Tom Horton, Owner Antelope Valley Kawasaki
Lancaster, CA

When the kits came out, Pete Schick, head of Yamaha Racing at the time, offered the kit to us for about $500.00 or so. We declined as we used Axtell cylinder heads and we were quite satisfied with them. In my opinion they didn't seem to add that much of an improvement and the only guys that ran them were the guys that got them for free.

But talk to Tom as he actually rode 1 for Shell Thuett. I just remembered I rode Shell's OW72 in practice at Ascot one night & I couldn't feel any difference from mine, just sayin'.
Devon Sowell
Last Edit: 31 Oct 2012 03:08 by Old59R.
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Wanted.......Yamaha OU72/OW72 750 Information 01 Nov 2012 21:05 #181083

  • MDFlat4
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Anyone know of a rider in Michigan during 70's & 80's that rode/owned one of these???
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Wanted.......Yamaha OU72/OW72 750 Information 01 Nov 2012 23:35 #181092

  • dt18k
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25 heads were produced. I had one on my champion framed 750. It had a megacycle cam set up for a rephased motor. Mine got thrown in the junk when I had problems with the rocker arms back in about 1980. Lynn Holloway also rode this bike a little bit. I know someone else in central Wisconsin that raced one in a Shell framed bike. He still has the bike but it hasnt been on a track since the early 80's. I think my standard head that we reworked and used sifton valves worked just as well. I also didn't think it worked all that well but mine had restrictors in it since I was a junior at the time. Lynn rode it as an expert without restrictors. Didn't seem be all great without restrictors.
Last Edit: 01 Nov 2012 23:38 by dt18k.
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 00:06 #181095

  • WildWill
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I think Darryl Hurst of Houston Texas Has one and I think
Gerry Booher of San Antonio has one too.
Willard Kelley
aka
Wild Will From Stephenville
6 Time VDTRA Pro #1
Sponsored By:
Tom Laird, L A Racing, Hearne Tx.
Terry McDonald of House of Wheels Racing, Brownwood Tx.
Rod Lake Racing, San Jose Ca.
Pam McDonald of All Star Awards and Signs, Brownwood Tx.
K-K Enterprises, Stephenville Tx.
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 00:10 #181097

  • DP126
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I'd have to dig it up, but I have the Cycle World article they did on the OW72. I believe the article stated as Larry did, they had 24 heads produced, along with the first one sent to Pete Schick, Yamaha race team director.

They basically bolted them to 24 fairly stock engines for homologation.

Shick, Roberts, Bud Aksland, Tim Withers, among others, worked for months to get the bikes ready for San Jose, where Roberts bike lost fire on the line for the main.

Some little electrical connector or something minor.
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 00:13 #181098

  • JHenry
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WildWill wrote:
I think Darryl Hurst of Houston Texas Has one and I think
Gerry Booher of San Antonio has one too.

Willard, at last years Ross Downs reunion, Darryl had a brand new OW72 head on display.
The most obvious difference (although there were several) was the absence of the cast
iron liners in the combustion chamber.

Jim Henry
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 00:49 #181102

  • MDFlat4
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There were more then 25 produced. I think close to 40-50 kits, that is documented in some paperwork I have. I have #25. It would be very helpful to me, to get Darrell Hurst's contact info. I have the original Yamaha paper work and some notes that came with the head I have. Darrell's name and Hurst Supply Houston TX are written in blue pen on one of the pages. I am trying to find out the history on what I have. Thanks
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 01:01 #181103

  • MDFlat4
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I have that 1976 Cycle World article. If you read it closely, it says they sent the first casting over for the team to start machine work and flow development. Later they had assembled the 24 motors for inspection. That would lead one to think they had 25 heads at that time. Then the article goes on to say "none of the 24 motors used for the inspection were actually used by Roberts" and "The team was preparing 6 bike to be ready for competition". This would make you think their was more then 25. Also it is from a magazine, which they can cook up their own stories and print what ever they want. That article might not be 100% actual facts. I will have to look where I have it that 40-50 were produced.
Last Edit: 02 Nov 2012 01:05 by MDFlat4.
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Wanted.......Yamaha OU72/OW72 750 Information 02 Nov 2012 01:45 #181106

  • WildWill
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MDFlat4 wrote:
There were more then 25 produced. I think close to 40-50 kits, that is documented in some paperwork I have. I have #25. It would be very helpful to me, to get Darrell Hurst's contact info. I have the original Yamaha paper work and some notes that came with the head I have. Darrell's name and Hurst Supply Houston TX are written in blue pen on one of the pages. I am trying to find out the history on what I have. Thanks

I will send you Darryl's Email address by P.M.(Private Message)
Willard Kelley
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Wild Will From Stephenville
6 Time VDTRA Pro #1
Sponsored By:
Tom Laird, L A Racing, Hearne Tx.
Terry McDonald of House of Wheels Racing, Brownwood Tx.
Rod Lake Racing, San Jose Ca.
Pam McDonald of All Star Awards and Signs, Brownwood Tx.
K-K Enterprises, Stephenville Tx.
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