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Thread: 851/888 Racebike Build

  1. #1
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    Default 851/888 Racebike Build

    Hi All:

    Looking to build an 851/888 for AHRMA's newly announced (but not yet fully approved) "Next Gen" Vintage Superbike class -- basically 83 to 92-ish 750 Fours/1000 Twins, per AMA rules of the time period.

    I've raced Ducatis for years, starting with 748s, moving to 996, then a 998, then a 749R, and now a 800SS. I don't have much experience with the 851/888 range other than I parted out a crashed 92 851 a couple years back. I've been reading through old threads here and absorbing as much knowledge as possible.

    So, let's start out with the basics: what's the best bike to use as the starting point for a racebike? The basic rules require the frame/swingarm/engine cases/bodywork to be from the same year, so we're really looking at which frame is the best platform? Other than the cross bracing, is there a difference between 92 851 frame and the later 888 frames? The 93-94 888s seem to be commanding $2k-$3k more than the 92 851, so that's a consideration.

    Lastly, if anyone knows of any good 851/888 racebike candidates, let me know. Even in the Strada versions, the bikes are rare enough that I hate parting out a nice streetbike to turn into a track hound.

    Thanks!


    Mark Hatten
    Wounded Duc, Used Ducati Parts Online
    Home of the Original "Loud Clutches Save Lives" T-Shirt
    www.woundedduc.net
    8-time AHRMA National Champion

  2. #2
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    With the '92' 851 frame it may be beneficial to altar the cross brace on the upper tubes so that it becomes removable and then you can use the one piece carbon airbox, similar to the factory racers.

    The 888 frames may benefit from having this brace fitted but the one piece air box will fit either way (provided you fit a removable cross brace).

  3. #3
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    Thanks. Obviously, they put the brace in the 851 frame for strength/stiffness. Did they make changes to the 888 frame that negated the need for this brace?

  4. #4
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    Yes, they put two smaller tubes acting as a cross-brace on the lower frame tubes instead.

  5. #5
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    So with the stock bracing in both, and -- ignoring the airbox issue for a moment -- is there a difference in the stiffness/strength of either frame?

    Thanks!

  6. #6
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    To be honest I don't know...but the factory racers continued to use the removable brace on the upper frame tubes.

  7. #7
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    Thanks. So here's what I'm thinking for the chassis of the bike (we'll get to the engine later). Feel free to offer comments on my plans.

    Forks: 998 Showas with Ohlins 25mm internals, or Ohlins R&T with 25mm internals. Cycle Cat top triple, spacers in lower. I already have the 998 forks (stock), so that's cheaper than going with the Ohlins R&Ts. They have more travel than the OEM 851/888 Showas, and they are better understood by most suspension tuners since they have more experience with them. Plus I can mount up 65mm 4-pad calipers without an adapter.

    Rear Shock: Ohlins or Penske. One of my sponsors is an Penske dealer, but I've had Lenny at Racetech work on my Ohlins stuff since my AMA days, and am very comfortable with his work.

    Brakes: 4-pad Brembos up front. Brembo snowflake rotors with STM buttons. I have some Brembo cast iron rotors, but not sure I trust 15-year old cast iron rotors on the track anymore. I used to run Brake Tech Axis iron rotors on my 749R, but had trouble with them developing cracks around the holes.

    Wheels: Marchesini 5-spoke mags if I can dig up a set. Otherwise, I'll adapt a set of Marchesini 5-spoke aluminum wheels from my 800SS.

    Bodywork: I've used Sharkskinz for years, so will probably stick with them. I've used FuelCel carbon/kevlar tanks on a lot of racebikes, but it doesn't look like he makes one for the 851/888. Anyone else? I'll need to come up with a belly pan to meet race regs as well.

    What's the availability of race parts like rearsets, aluminum subframe, front CPU mount, etc.?

    Thanks!

  8. #8
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    Hi Mark I am also considering the same initially my thoughts have been around getting my 1990 851 streetbike to race spec for the upcoming Phillip Island Classic and the rules will be either theirs or AHRMA. I also have Traxxion setup 996 forks, cycle cat triple and 4 pad Brembos to to fit but I am more concerned about Horsepower and trying to get to a more reasonable level of performance. What does AHRMA specify for displacement and mods?

    Cheers
    Erv
    BTW I'm the Brit that bought those 900ss side panels off you at Barber a few years ago

  9. #9
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    Hi Erv:

    I figure 120 hp or so will put it on par with the 750 fours. The rules won't be final until the AHRMA board meeting the Monday after Barber, but they will essentially mirror AMA Superbike rules from the period. Bikes must use stock cases. 750s will be allowed a 2 mm overbore with stock stroke. Twins are allowed up to 1000cc; stroke and bore can be modified.

    Chassis is pretty open. OEM frame and swingarm, may be braced. Any forks of like style (USD or conventional) can be used. Any non-radial caliper(s), any non-carbon and non-wave rotors may be used. Any non-CF wheels may be used. Bodywork must closely replicate OEM for the year, make, and model.

    I figure I'll get the chassis dialed in then start building up a race motor. As always, it will be much cheaper and easier to go fast on a 750 four-cylinder, but where's the fun in that?

  10. #10
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    I have just restored a 83-85 championship winning CB1100F that was sitting dormant for 26yrs and it will be going to Phillip Is along with the original rider and I also have his 85 GSXR750 slabside that won back in 86. I'm planning to ride the GSXR at the event but my heart is in the Ducati (as always) as such its now time to decide which way to go as they need to be shipped to Australia by early November. The 851 is a good basis but I was hoping for more than 120 at the rear but I have to be realistic. Are you thinking of going to 916, 944 or higher?

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