I just grabbed this from the lta site
7. MOTORCYCLES
MOTORCYCLE OVERVIEW
Motorcycle records are kept in 6 Categories:
OHC (Overhead Cam), Pushrod, 2-Stroke, Twins, Classics, Electric
Motorcycle Records are comprised of three components:
Motorcycle Class, Engine Type, Engine Displacement/Voltage
For example: MPS/CBG-1350/4 Class –Modified Partial Streamliner
Type – Classic Blown Gas
Size - 1001 - 1350cc. /4 stroke.
CHASSIS AND BODY DESCRIPTIONS
PRODUCTION (P)
A: Production Class is for motorcycles that are stock IN APPEARANCE.
B: Visible engine components must be OEM for the model.
C: Changes to the fueling system, engine, air intake, computers and exhaust
system that are not apparent to exterior view are permitted.
MODIFIED (M)
A: The modified class is for motorcycles BASED on production models.
B: No aerodynamic aids on the front. Commonly referred to as “NAKED”.
C: Removal of the front fairings is usually all that is required. (see rules.)
D: Modifications to the other bodywork is limited.
E: Modifications to the engine, swing arm, tank, pegs are allowed.
MODIFIED PARTIAL STREAMLINER (MPS) Same as Modified(M) with:
A: Aerodynamic aids allowed per rules.
B: Most modern sport bikes with a “chip and can” fall into this class.
C: Custom bodywork is allowed as defined in the rules.
ALTERED (A)
A: Altered is for specially constructed and purpose built race bikes.
B: Aerodynamic front fairings are not allowed.
C: May use 1 or 2 engines of any design.
D: May use non-motorcycle engines. (PRIOR APPROVAL REQUIRED)
ALTERED PARTIAL STREAMLINER (APS) Same as Altered(A) with:
A: Aerodynamic fairings allowed. The rider must be visible per the rules.
B: Modified Class motorcycles with custom APS fairings fall into APS.
SIDECAR (SC)
A: Modified or Altered class motorcycles with a sidecar attached.
B: Riders are not permitted.
STREAMLINER (S) AND SIDECAR STREAMLINER (SCS)
A: Extensive design and construction required.
B: Roll cage, fire suppression, driver restraints, fire suit, etc. required.
C: May use 1 or 2 engines of any design.
D: May use non-motorcycle engines. (PRIOR APPROVAL REQUIRED)
ENGINE TYPE DESCRIPTIONS
MOTORCYCLE ENGINE DEFINITION
A: Engines originally designed for use in motorcycles.
b: Engines originally designed for motorsports vehicles that were also offered
in motorcycles in a volume of 500 units.
NON-MOTORCYCLE ENGINE DEFINITION
A: Engine originally designed for automobiles or non-transportation purposes.
B: Motorsports engines not sold in motorcycles in a volume of 500+ units.
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PRODUCTION – (P) For all engine classes.
Production engines must be the same model as the model of the frame being
used and must have STOCK EXTERNAL APPEARANCE with OEM cylinders,
heads and crankcases. OEM engine displacement determines the displacement
class for competition. Starter must be retained and operable. Carburetors or
throttle bodies must be OEM for that model production engine. ALL
PRODUCTION ENGINES RUN IN GAS (G) CLASS.
VINTAGE – (V) For all Engine Classes except Classic.
Limited to motorcycle engines produced prior to 1956. Non-OEM cases and
heads allowed so long as dimensionally equivalent to OEM.
2-STROKE (/2)
Defined as an engine operating in a 2-cycle fashion.
A: Motorcycle Engines Only - Production and Modified Frame Classes.
OHC
An engine with overhead cam operated valves as defined below.
The camshaft location must fall within the following limitations:
A: Above the valve train.
B: No more than the crankshaft stroke below the OEM cylinder deck.
C: Pushrod length less than twice the crankshaft stroke. (BMW air/oilhead.)
PUSHROD (P)
Any engine with push rod operated valves as defined below.
The camshaft location must fall within the following limitations:
A: At least one crankshaft stroke below the OEM cylinder deck position.
B: OEM pushrod length at least twice the crankshaft stroke.
C: Replacement heads must have the same number of valves as originally
produced for engines of the same series in Production.
TWIN (T)
Any 4-stroke single or twin cylinder motorcycle engine:
A: Pushrod and OHC engines (as defined above).
B: Any cylinder angles between 0 – 180 degrees for twins allowed.
C: Motorcycle Engines Only.
CLASSIC (C)
Any 4-stroke air cooled motorcycle engine:
A: Manufactured between 1956 and 1986 inclusively.
B: Non-OEM cases and heads allowed so long as dimensionally
equivalent to OEM.
C: Alteration of cooling fin design, size and placement is allowed.
D: Enhanced cooling is not permitted. (ie. water injection, nitrous oxide or
water spray, radiators, enlarged or modified oil systems.
E: Fuel system may be upgraded. OEM carbureted to remain carbureted.
F: OEM fuel injection may be retained, modified, replaced by carburetors.
G: One distributor or magneto allowed.
H: Computers allowed for data collection purposes only.
Electric (E)
Electric is defined as propulsion via electric motors only.
A: Hybrid or ICE generators used to power electric drive motors not allowed.
C: Dual drive motors allowed in Altered class only.
Electric power shall be designated in the LTA records as a fuel class:
i.e. M/E-48 = Modified/Electric – 48 volt.
my interpretation of the production rules would be that a busa must be in the 1350 class, a zx14 would be in the 1650 class, a goldwing would be in the 2000 class and a Rocket 3 would be in the 3000 class.
You would have to talk to one of the race directors to know for sure. we are allowed to race higher displacement classes in mps and aps at a disadvantage where there is no size limit based on oem specs. whatever your motor size is in that case you race that class or higher. looks like the size limit rule has been forgotten???
it would be nice to know what the rules really are as i have a friend that may have a big change in build plans for either 1350 or 1650 production