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Thread: Pridmore BMW engine and maybe frame located in West Texas?

  1. #1
    Registered User winsur4's Avatar
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    Pridmore BMW engine and maybe frame located in West Texas?

    IMG_0452.JPGIMG_0459.JPGA good friend and rider is in possession of a BMW R90S - cafe purchased as a basket case that was located near Austin - Leander. It was advertised having the Pridmore engine from San Jose BMW on the MOA classified in the late eighties or early nineties. Delton had Ray Randolph of Midland Texas (he was a builder of the 10 gallon tanks for Perry's Sidecars) assemble it for him. They started it up and drove it, and it was very fast, but not ride-able on the street. It has been setting in an airport hanger covered with a tarp since. He would like to verify that it is a Pridmore, and also sell it.

    It has a reinforced frame similar to the one pictured on the San Jose BMW website.
    It has a reinforced swing arm that was made at San Jose BMW.
    The motor has short cylinders typical of the Pridmore engines.

    I am trying to gather information about these engines, and what if any provenance this setup has. The engine number shows it to have been based on an R90/6 The frame was powder coated after purchase and has the bracing typical of the San Jose racing frames. the front end is a stock non braced R90/S. It has flat slide Mikunis, and a nice 2 into one exhaust.IMG_0449.JPG
    Last edited by winsur4; 09-24-2014 at 09:31 PM.

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    Cupcake greg's Avatar
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    Not absolutely sure but I think the SJ BMW bikes had the frame brace that ran from just below the steering head to just above the swingarm plate. That might have been a later addition.

    Edit: Found a picture of it here http://www.cycleworld.com/2013/05/31...erbike-racing/ where you can see the brace. You can also see different brakes on the forks.

    SJ BMW did a lot of those mods for folks who wanted better handling as well as a pretty good catalog of speed parts. All available to those that had deep enough pockets.
    Greg
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    2014 R1200RTW, 2013 Paiggio BV350, 2010 Yamaha TW200, 1978 R100/7

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    Registered User toooldtocare's Avatar
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    San Jose BMW did my Motorsport. The bill came to well over $3K for mods in 85. Their work was well done, the bike was still running good when I sold it in 2012.

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    Administrator 20774's Avatar
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    A page from the May 1980 Cycle Guide talking about the R100S sports pack. This shows the swingarm (bottom side shown). This SJ brace appears to be welded differently than the OPs swingarm brace...suggesting that the OPs is not from SJ.

    Note also the front-back frame brace.
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    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    All the special speed?/handling parts suppliers back in the day for airheads had their braces, top triple clamps, springs, shocks, etcetera. There should be a few airheads out there with these now extinct parts. I know of one for sure. Fun hobby, pockets have to be deep as time goes by. Drip drip squirt squirt works for me. OMG, I can't hear the fuel pump! Hey, where's my IFAD? Where's my horse?

  6. #6
    Registered User winsur4's Avatar
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    Quote Originally Posted by greg View Post
    Not absolutely sure but I think the SJ BMW bikes had the frame brace that ran from just below the steering head to just above the swingarm plate. That might have been a later addition.

    Edit: Found a picture of it here http://www.cycleworld.com/2013/05/31...erbike-racing/ where you can see the brace. You can also see different brakes on the forks.

    SJ BMW did a lot of those mods for folks who wanted better handling as well as a pretty good catalog of speed parts. All available to those that had deep enough pockets.
    Quote Originally Posted by 20774 View Post
    A page from the May 1980 Cycle Guide talking about the R100S sports pack. This shows the swingarm (bottom side shown). This SJ brace appears to be welded differently than the OPs swingarm brace...suggesting that the OPs is not from SJ.

    Note also the front-back frame brace.
    The frame braces are not in the picture, but I have them. Seems the flat slide carb was in the way of mounting the cross brace so it was left off. If you look carefully at the frame, you can see the attachments for the brace. The swing arm brace looks similar except for the added laterals. Since this was for the R100, I wonder if it was beefed up or redesigned for extra strength later. This appears to be an r90/6 modified frame. Not sure as the powder coating obscures any frame stamps, and there is on other markings to identify it. The engine number is from an 76 R90/6, which makes sense, as who would want to take an R90S engine and modify it? The front end is not modified, and appears to be from a stock R90S. It is odd, though that a braced frame and swing arm would be mated with a stock front end. SJ BMW made a very nice brace, which I have on my R90S.

    I am really more interested in the engine. It has the shortened cylinders and lightened flywheel. It was advertised as a "Pridmore" engine when in the MOA magazine classified add. I know the history of Reg Pridmore, but there is precious little about who made the engines, except, of course, the famous racing engines made by SJ. Were there clones made by others besides the ones produced by SJ? I am just not sure what I have here. Is there a way to identify who made the engine? Special rocker arms? Lightened push rods. For sure it has the shortened cylinders as seen in the picture. The cylinder has been shortened by 3/4 of an inch. Also, it took very high octane gas to keep from pre-detonation. It would not idle below 2000 rpm, probably due to the light flywheel.

  7. #7
    Benchwrenching PGlaves's Avatar
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    Udo Gietl (not sure of the spelling) was the bike builder for the Butler & Smith bikes raced by Reg. At least some of the time Tom Cutter (Rubber Chicken Racing Garage) was on the B & S team. Ask Tom if he can identify the engine.

    From the pictures I'm fairly certain that is not a B&S race bike but don't know about the engine.

    And possibly the original reference to a "Pridmore bike" means nothing more than modified by RPM when Reg owned the dealership.
    Last edited by PGlaves; 09-25-2014 at 03:41 PM.
    Paul Glaves - "Big Bend", Texas U.S.A
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    Registered User lkchris's Avatar
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    Nice article on Udo Gietl in current issue of Road Racing World magazine
    Kent Christensen
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    Administrator 20774's Avatar
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    1979 Cycle article on Udo - King of the Boomers:

    http://www.omnilex.com/public/bmw78/boomers.html
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #10
    Registered User winsur4's Avatar
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    Quote Originally Posted by PGlaves View Post
    Udo Gietl (not sure of the spelling) was the bike builder for the Butler & Smith bikes raced by Reg. At least some of the time Tom Cutter (Rubber Chicken Racing Garage) was on the B & S team. Ask Tom if he can identify the engine.

    From the pictures I'm fairly certain that is not a B&S race bike but don't know about the engine.

    And possibly the original reference to a "Pridmore bike" means nothing more than modified by RPM when Reg owned the dealership.
    I just talked to Johnny Williams in Lubbock. He was there when Ray Randolph built the bike and actually rode it. It would fly, but was not for street use. Johnny told me that one of his BMW acquaintances "Stoner" knows Reg Pridmore, and said that Pridmore kept records of all the engine case numbers he used to build engines. So I am going to try to contact Pridmore and see if #4971039 was one of his engines. I guess I could try contacting his motorcycle training course. It would be nice to know what was in this engine besides the obvious short cylinders.

    Another tidbit, Delton thinks he bought it from Mark Brightwell in northwest Austin TX. I don't wonder if he is still driving BMWs?
    Last edited by winsur4; 09-26-2014 at 02:39 AM.

  11. #11
    Registered User winsur4's Avatar
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    I was visiting Odessa and decided to pull a valve cover to look at the rocker arms to see if there was anything special. I noticed the peening of the arm. Does anyone know what that was for. And is there anything unusual about the springs, retainers, etc?.
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    1971 R75/5 - 1974 R90/S
    1974 R90/6 - 1977 R100/7
    1996 R1100RT - 1975 Norton MKIII

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    Administrator 20774's Avatar
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    It all looks normal to me...I don't see anything special...peening (if done) creates surface compression in the material and helps prevent it from cracking. About the only thing I wonder about is the spring retainer. It appears a little different than my stock /7 head...picture attached. Your picture shows it to be shinier...maybe a different material...lighter, stronger, .
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    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    B Reams brook.reams's Avatar
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    Racing Push Rods

    The push rods are the racing versions. I have a set in my R75/5"S" bike from my days racing that bike when I first bought.

    IIRC, they are hallow, sodium filled, and made the shafts are titanium. Mine weight about what a small handful of paper clips weight.

    Cool stuff.

    Best.
    Brook
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    Brook Reams - Arvada, CO
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    2004 R1150-RS || 2002 F650-GS || 1975 R75/6 || 1973 R75/5

  14. #14
    Registered User winsur4's Avatar
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    Rocker Arms and springs

    The valve springs look a bit different to me. Do ou recognize any thing about them? the picture from the side shows them as best I could do.
    1971 R75/5 - 1974 R90/S
    1974 R90/6 - 1977 R100/7
    1996 R1100RT - 1975 Norton MKIII

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    Registered User toooldtocare's Avatar
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    PM sent.

    Wayne

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