Motorcycle displacement issues...

[JackD]

The new bike rules are as ill advised as any you have ever seen and the objective as clear as fudge.
At least the car guys are starting to pin down the size of the roadster.
"A design that failed or failed by design."

[Nortonist 592]

We have in the club archives some SCTA minutes from the late 30s, early 40s.  The minutes from March 17, 1941 has Vic Edlebrock "attempting to define a roadster"  Things have'nt changed that much.

[Dean Los Angeles]

2006 Rules and Records Dry Lake Speed Trials:

7.B.13   Engine size: Displacement must be greater than the maximum allowable for the next lower class. To permit minor reconditioning of worn cylinder blocks, in classes other than Production, it is permitted to increase cylinder bore diameter .020 inch (.508mm) beyond that which provides maximum displacement for the class. In all cases, the resulting displacement must be exceeded to qualify for the next higher class. The .020-inch (.508mm) will be discounted for record certification and will be noted on the certification card and in the logbook.

7.J.1   Production: Production engines must be the same model as the model of the frame being used and must have STOCK EXTERNAL APPEARANCE. Production motorcycles must use OEM cylinders, heads and crankcases to comply with this class. OEM engine displacement determines the displacement class for competition. Displacement may not be increased beyond that class limit. Starting mechanism must be retained and operable. Carburetors or throttle bodies must be OEM for that model production engine. All production engines run in gas class. (See Section 7.D.3)

7.J.10   Class VG and VF: Same as Class G or F, except that the class is limited to motorcycle engines produced prior to 1956. For reasons of historical authenticity, vintage engine modifications are restricted to older technology levels, so far as is practical. Accordingly, in classes VF, VG, VBF and VBG, newer technologies, such as EFI or electronic reactive ignition systems, are not in keeping with the spirit of the Vintage Classes and are not allowed. Computers are allowed for data collection purposes only.

Engines must utilize O.E.M. crankcase, O.E.M. cylinders on flatheads and two strokes and O.E.M. heads on O.H.V. engines. Above components made after 1955 and exact reproductions may be considered legal in Vintage classes if they offer no competitive advantage. Pre installation approval by the contest board is required. It is the entrant?s responsibility to provide documentation and samples. A .050 inch overbore is allowed on vintage engines only (including production vintage) and will be discounted when the bore size is measured.

Flathead engine displacement will be discounted 33 1/30/0 in determining engine displacement class limits. For example a 1500cc measured displacement would run as a 1000cc.

Note that for Production classes what the O.E.M. calls the displacement is what matters, not anything you can do to it later.

[JackD]

The clean up over bore is just as valid for the Production MC as anything else unless
 the friend the rule was made for doesn't run Production as has been pointed out.
If you are a car guy, the blocks must be cheap enough you don't need it even if you run a MC motor.
All that stupidity is very telling isn't it.
And you thought it couldn't get worse ?
 Brace yourself.

[Nortonist 592]

The rule states for the production class that "OEM engine displacement determines the displacement class for competition.  Displacement may not be increased beyond that class limit."  So from what I can read the rule says you don't get the .020 overbore for production class.

[JackD]

If you follow that logic to it's obvious conclusion then Scott's 30  year flat heads
 are allowed nothing because ya just had to be there.
I saw the overbore deal tried the first time and with a little enlightenment the Board laughed it down.
 The proponent even lied to say it was common in other racing but he was unable to name any.
 The next time the following year it was snuck by them.
If you are a car guy that uses a bike motor, none of this counts and you need different friends.
And there you have it.

[Nortonist 592]

Scott Guthrie,  You are correct on all but the flathead displacement "advantage".  They get to according to the rules run a 50% greater displacement than the class limit.  i.e.  a 750cc flathead Harley or Indian or whatever you have runs with 500cc OHV.  To me it looks like an AMA leftover.

[jprovo]

SaltyBlaster-
Great bike, I'm going to be taking notes on it as soon as we get the P-PP bike finished. Maybe copy it for my streetbike!! I'm hoping to run at El mirage this year, but progress is slow. Nothing a lot of time and money can't fix

James

[Nortonist 592]

I do believe that the advantage applies only in the vintage class.  But I'm open to correction.

[JackD]

Not all the jokes are in the rule book.

[Bob Drury]

...and not all the Jokers on this site are playing with a full deck..........

[JackD]

Some are not playing and take it pretty seriously.
The trick is not to lose to them in either case.

[Hans Blom]

Figured I would ask on this thread since it about bikes...initially.....Anyone know of Terry Lewis? he set a few records in Vintage 750 on a BSA in 99 and 2000. Just curious about his bike and story.

[Nortonist 592]

Hans,   Terry is a member of the San Diego Roadster club.   His BSA is a quick one alright.  If you contact the SDRC I'm sure they could put him in touch with you.  I hear this year he is bringing out a BSA triple.  I have a very short video of the BSA, taken a few years ago.  I can put it on DVD but I'm not sure if it will play in Europe.  If you want to take a chance I can make a copy and send it to you.

[JackD]

Check your PMs in a bit for the contact information.