The building of my vintage racer

Discussion in 'Airheads' started by FreeTheBeast, Apr 24, 2012.

  1. supershaft

    supershaft because I can

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    Improve torque? Comparing 32mm Bings to Dell's and Mikuni's, so do bigger carbs with more top end than the their smaller siblings. Why not have it all? It's rare when you can and in this case you can.
  2. Voltaire

    Voltaire Bored Of The Rings

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    I run 36mm on my R90 race bike with some 60 mm screened trumpets to keep out rocks and small children.
    I bought them years ago to put on my Ducati which has 32mm carbs. Never bothered at the Ducati goes so well and its a torque monster in a way BMW owners can only dream about.:rofl
    20 years ago :cry I fitted 40mm Dells to an R100 with twin plugs, later flywheel etc and it ran really well and behaved nicely.

    36's would probably go nicely on a 750 BMW race bike.
    Best prices I have found is Bevel Heaven, I'd avoid used ones and slides are very expensive and they wear out.
    The PFM series covers 30 to 36 i think....then it PHM for 38/40

    SS is right on the rubber mount, I have mine fixed but with a thick insulator sleeve.....works but not ideal.
    I use a Tommaselli twin pull , works nice, and cables are easy to make up, would suggest the 45 degree turning sleeve for nice smooth cable route.

    dang.....its Saturday and I have to go to work....might take the Norton for a blast...:D
  3. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    30-36 is PHF
  4. Voltaire

    Voltaire Bored Of The Rings

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    wot he said......I should have gone to spec savers.....:rofl
  5. supershaft

    supershaft because I can

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    PHM's come in 41mm too.

    I hear what you are saying about air cooled Ducati's and low rpm power. That is until the new retro ducks came out. They have very little low rpm power. Not near enough IMO. Beemer riders have a clue if they have ridden old K100's. Their power curve reminds me of older ducks.

    Personally, I think you are better off tilting the Dells in just a bit and running the cables without the elbow for easier pull. That and light Dell springs. Disconnecting the pumps really lightens the pull too besides really quickening your rev through the midrange if rejetted correctly.
  6. Voltaire

    Voltaire Bored Of The Rings

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    might give the tilted carb idea a try....saves me having to re solder the nipples...:rofl
    I'd look at Mikunis but we are not allowed any Jap parts in classic racing here.

    I had a rubber bandy 2 valve Duke for a couple of years, 80 hp they said....would rev to over 9k....:evil a real licence looser...
    sort of gave the feeling of the bevel but not quite.....its long gone but the bevel remains...:D
  7. FreeTheBeast

    FreeTheBeast Shunpiker

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    I'm formulating some big plans for this bike. It might be done and over for racing this season - all for the better racing next year and beyond. :evil

    We can build it better, faster, stronger...and hopefully for less than $6M.
  8. FreeTheBeast

    FreeTheBeast Shunpiker

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    I've been studying up on high compression pistons and lifted motors. The bike is definitely done for this year. Cylinders are already off the motor block. Siebenrock has some mighty nice looking items.

    Lifting the motor (obviously) requires some fabrication. Anyone have any first hand experience? I have seen that one method is to put the rear motor mounts through the center of the frame with the front bolts on top of the frame. There are also kits that raise the motor without any welding. I think the drilling/welding route is the better method.
  9. Voltaire

    Voltaire Bored Of The Rings

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    My engineer mate makes these,I have a set on my bike.
    The sleeves are tapped and go thru the motor. The rear mounts get drilled and tapped when you line up the engine/box/swingarm to your liking. All the original engine covers still fit too but you need to move the coils a few mm.
    [​IMG]
    Raises the front up about 30mm.Overlap on shaft/final drive is reduced by about 5-8 mm.
    I have touched the RH head down on a few occasions as I'm not much of a hanger offer....( maybe I need a set of Continental :rofl)
    We tried out the welding method on a stuffed frame but decided the bolt in one would do as racer may go back on road one day....
    [​IMG]
  10. Padmei

    Padmei enamoured

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    You may want to talk to Voltaire

    http://advrider.com/forums/showthread.php?t=808692
  11. FreeTheBeast

    FreeTheBeast Shunpiker

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    Thank you for your perspective. The bolt-on option certainly might be a little easier. Tapping holes in the motor - I suppose one had better do it right the first time. :D


  12. Box'a'bits

    Box'a'bits In need of repair

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    I think you read that wrong.

    Where do your motor mounts go now? :wink:
  13. FreeTheBeast

    FreeTheBeast Shunpiker

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    My motor mounts are still in the stock positions now.
  14. Voltaire

    Voltaire Bored Of The Rings

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    The bolt on ones have threaded 12mm aluminium sleeves that replace the motor mounting studs, The rear frame mount has been left undrilled/tapped to facilitate correct engine/tranny/drive alignment.
    I like it as its non invasive and can be reversed if bike is not longer on race duty.:D
  15. FreeTheBeast

    FreeTheBeast Shunpiker

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    So is shimming the driveshaft not required? I thought I read somewhere that some shimming was required when raising the motor.
  16. supershaft

    supershaft because I can

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    Some people move the engine forward as well as raise it. I probably would.

    Remember that the engine is stressed on our bikes and a very important part of frame rigidity. That kit seems like it would negate some of that.
  17. LoJack

    LoJack Long timer

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    Supershaft, It looks like it will move the engine forward about the same amount.
  18. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    You want to keep the u-joint of the driveshaft in the same spot vertically that it was before. The driveshaft is free to move up and down on the front end, but at the back the splines in the final drive are fixed. If you move the driveshaft forward or backward, up or down, you're changing the axis of the driveshaft in relation to the rotating axis of the final drive input spline. The only way these two can remain coaxial throughout the suspension travel is if the u-joint at the front of the driveshaft is directly inline with the pivoting axis of the swingarm. Not watching out for that will result in undue wear on your final drive input and drive shaft splines. Since the whole mess is drenched in gear oil, the wear probably wouldn't be that rapid though.
  19. Voltaire

    Voltaire Bored Of The Rings

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    Its bolted in to the lower frame but its not really a stressed member like a Ducati of K series...imho.
    Probably looking at a top mount at some point but at this stage the handling is fine for the power its putting out....what ever it is.
  20. Voltaire

    Voltaire Bored Of The Rings

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    Good points I had not concidered.The drive shaft is bolted up to the gearbox flange as per normal, its the other end that has its overlap reduced.:evil
    But yes the u joint is no longer is sync with the swingarm.
    It is however more lined up than the stock set up.......ummmmm
    The reality for my bike is that it only does not do a lot of miles per year.
    I was wondering if as its a race bike am I losing power churning all that EP 90 around in the box and FD.....could I go to lighter oil?:ear