BMCRC/BMZRC MZ Technical Regulations
2011 Season

**** Pending 2012 Version****

BMZRC Technical Committee
Please contact a member of the Technical Committee if you have any questions. See Contact Us page for details.
Chairman: Steve Cannon
Member: Tony Holmshaw, Brian Rogers, Martin Baldwin

Eligible machines

MZ TS & ETZ 250 & 251 Plus 301 & Saxon swinging arm & frame only. Crankcases Barrels Heads Forks Carburetor Frames Swinging arm & Tank must be from Eligible machines only. Modifications are permitted where they do not contravene any other rule.

Engine

The bore shall not exceed 72mm All engine Nos. must be visible Liquid cooling is not permitted The carburettor shall be mounted in such a way that induction is only through the barrel. Reed valves are permitted. The clutch shall be mounted in its original position on the crankshaft Only a standard 65MM stroke is permissible No more than five gears are permissible

Frame

Silhouette and geometry of the frame shall be as the original. Removal of any part shall be allowed. No strengthening or bracing is permitted except as normally required for the fitting of rearsets and seat. No welding to the frame may be carried out except for repairs. The onus is entirely upon the rider to ensure that such repair cannot be construed as strengthening the frame.

Swingarm

Silhouette and geometry of the Swingarm shall be as the original. Removal of any part shall be allowed. No strengthening or bracing is permitted. No welding may be carried out (except for mounting of a chain guard). Fitting of a chain guard is required but it’s fitting must not contravene any other reg.

Rear suspension

Only twin shock absorber rear suspension units mounted in their original positions are permissible.

Forks

Must maintain a similar silhouette to the original (shortening, removal of brackets etc is allowed).

Seat

Any seat unit may be used provided no part projects further forward than the original fuel tap position nor more than 100mm below the bottom of the top horizontal frame tube and no other regulation is contravened.

Carburettor

Must be single original BVF carburettor remaining externally standard except as below with NO additional fuel metering device (e.g. power jets) internally or externally.
The Carb bottom vent must be fitted with a pipe draining to a 250ml catch bottle. The only external modifications permitted are:

• Drilling to allow venting of the float bowl and the fitting of nipples to allow pipes to be fitted to same. Where fitted these must be secure, fuel tight and run to a position under the tank and terminated with non-return valves or run to the catch bottle for the bottom vent.
• The fitting of a suitable connection to replace the existing to the bottom of the carb breather.
• The changing of the fuel inlet stub.
• The throttle slide pin may be replaced or re-fixed and glued in.
• The bore maybe widened to a maximum of 35mm.
• The carb inlet opening may be shaped within the existing material.
• The carb may be repaired engine side and built up around the repair if required with liquid metal or similar.

Tank

Must maintain profile of the original (including the original style of filler). Slight modification to allow interchangeability, indentation for clipon clearance and fitting of additional fuel tap in mirror position to original shall be allowed. Repairs are allowed where they do not contravene any other rule.

Brakes

Any type of brake and any modifications to standard brakes are permissible.

Streamlining

No fairing, frontal or rear enclosure is permitted.

Interchangability

Of parts from eligible machines is permissible.

Exhaust system

The down pipe must be standard or pattern (not fabricated). No modification is allowed with the exception of a reduction in length from the silencer end of the pipe. The minimum length of the down-pipe is 440mm (Fig 2) measured on the outside radius from the barrel lip to the end of the pipe. The pipe must be clamped to the silencing system. The pipe must be clamped or securely connected with springs (small loops may be welded to the pipe and silencing system to facilitate this) to the silencing system. Welding together of these two parts is not permissible. The silencing system must retain the dimensions and silhouette of a silencing system from eligible machines up to the first weld at the rear end of the long diffuser cone. (Section A in Fig 1). To the rear of that weld (section B in Fig 1) any modification is permissible provided it does not exceed 91mm exterior diameter.

Fuel

Any leaded or un-leaded fuel up to 100 RON is permissible.

ACU road race regulations

All machines must conform to the ACU road race regulations.
NB. The purpose of the regulations is to promote close racing and reduced costs by controlling the performance advantages that may be gained by modification and maintain the basic identity of the original machine. Where dimensions or types are stated the regulations will be interpreted strictly. For example it is important to remember that a downpipe that is 439 mm long is outside the regulations and if discovered will result in exclusion. You are responsible for making SURE your machine conforms