Tech Regs

Download 2019 Tech Regs


Technical regulations 2019





Eligible Yamaha models



Parts that must remain standard and not be modified

regardless of model



Parts allowed to be modified regardless of model



Parts allowed to be removed regardless of model



Model-specific regulations

5.1 RD250/350 LC


5.2 RD350YPVS


5.3 RD350LC/YPVS Hybrid


5.4 TZR250


5.5 TDR250









Technical inspection





*Changes to regulations for 2018 are highlighted

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Section 1: Eligible Yamaha Models

1.1Road-going 250 and 350 parallel twin two-strokes, model type; 1.1.1 LC Model is RD250LC 4L1 & RD350LC 4L0

1.1.2 TZR Model is 2MA and 1KT parallel twin 1.1.3 TDR Model is 3CK and 2YK

1.1.4 YPVS model is RD350LC2, RD350N, RD350N2, RD350F, RD350F2, RD350R

1.2Only models of the same spec as the officially imported model.

1.3Reverse cylinder or V-twin model TZRs are not acceptable.

1.4Models with larger rim sizes or brake diameters than the official models are also illegal.

Section 2: Parts that must remain standard and not be modified regardless of model

2.1Frame and subframe, with the exception of minor modifications permitted in the list in sections 3.12 and 3.13

2.2Swingarm must be from the relevant model and standard, other than the compulsory fitting of a lower run chain guard. (LC exceptions: rules 5.1.3-5.1.4, TZR exception: rule 5.4.1)

2.3Cush drive and sprocket carrier

2.4Primary drive gears

2.5Gearbox must be from the officially imported model of the relevant motorcycle

2.6Ignition control units must be from an officially imported model of the relevant motorcycle. No remapping or FIII kit boxes are permitted. (LC/YPVS exemption: rule 5.1.13)

2.7No system may be fitted that will affect a dyno’s ability to take a correct power reading

2.8No redundant electrical systems are permitted

2.9Powervalve systems, if applicable to model, must be from the relevant motorcycle and must be fitted and fully operational

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Section 3: Parts allowed to be modified regardless of model


3.1Internal petrol tank filters and taps may be modified or removed but otherwise fuel tanks must remain as standard for the model

3.2Fuel tank cap can be modified or replaced, subject to ACU regs


3.3Static ignition timing may be altered

3.4Electrical components may be repositioned, and waterproofing measures taken

3.5Rotor lightening is allowed


3.6Barrels and head can be modified

3.7Crankcases may only be modified to match cylinder porting and the only permitted crank modification is the use of a full-circle crank

3.8Sprocket cover may be modified or removed

3.9Airbox may be modified or removed

3.10Radiators, cooling system and thermostat may be substituted or modified

3.11Rebores to a maximum of 2.75mm (no big bores)

3.12Aftermarket billet clutch and non-OE pressure plate, extra plates and replacement springs are permitted

3.13Exhausts can be modified or replaced with alternatives. Any exhaust must conform to the ACU noise limit of 105db

3.14Powervalve control boxes may be modified with the use of ‘Dip Switches’ or re-soldering of the internal motherboard. The Powervalve control box must be Yamaha OE and applicable to the relevant model


3.15Minor frame and subframe mods are allowed for cosmetic reasons, bodywork fitment and steering damper mods, but not to change geometry, lightening or bracing. The final rear cross brace must remain in standard position on all models, cutting the rear subframe to this point is permissible to facilitate the fitment of non-standard seats

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3.16Ancillary frame brackets can be removed, typically unused mounting lugs, additional lugs may be added to assist the fitment of bodywork

3.17Chassis and wheel bearings may be upgraded to superior specification, but must be to standard diameter

3.18Fork internals, sliders and caps may be modified or replaced with cartridge kits of higher specification. Forks may be shortened

3.19Rear shock may be re-gassed, spring may be replaced to suit riders’ requirements. Alternatively, any commercially available shock absorber may be used. This must be of single unit construction. No remote reservoirs, piggy back reservoirs or remote pre load units will be allowed. The unit must also be a direct fit to the existing mounts without modification to the frame or linkage. LC can use any shock as long as it is a direct fitment

3.20Rear suspension tie-bars may be modified or replaced to modify the ride height

3.21A steering damper is allowed

3.22Handlebars can be modified, replaced and remounted with due consideration paid to clearance of fairings and bodywork

3.23Race bodywork can be fitted, but must not alter original silhouette at front of bike. Seat unit may be replaced with any suitable unit


3.25Double bubble and tinted screens are allowed

3.26Wheel spindles, subject to use of original material and thickness. They must be at least standard length and may be lengthened to allow use of R-hook

3.27Rear brake fluid reservoir. The ‘HRC’ tube modification is allowed

3.28Any mass production fixed ratio master cylinder for front and rear braking system may be used. This does not mean race production Brembo, AP Lockheed or bespoke units.

Section 4: Parts allowed to be removed regardless of model

4.1Equipment for road use like mirrors, horn, indicators, pillion pegs and ancillary brackets originally to support road-going parts

4.2Top chainguard (a bottom run ‘sharks fin’ toe guard must be added as per ACU regulations)


4.4Speedo, cable and speedo drive. The speedo drive can be substituted for a suitable spacer

4.5Charging system, including regulator-rectifier and battery

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4.6Oil tank and pump


4.8Kickstart mechanism

4.9Gearbox sprocket cover


4.11Rear brake fluid reservoir

Section 5: Model-specific regulations

Section 5.1: RD250/350 LC non-power valve 4L0 and 4L1

5.1.1250LC is allowed twin discs and callipers from the 350LC

5.1.2YPVS forks, wheels and brakes can be fitted

5.1.3Swingarm bracing and period aftermarket swingarms are allowed

5.1.4Any class-legal YPVS bodywork/frame/swingarm part can be fitted, (with the exception of full fairings )

5.1.5TZR forks, wheels and brake may be fitted, along with the rear wheel, The ‘Blue Spot’ front calliper may be used ONLY if the bike is fitted with TZR forks. See TZR rules for full definition of this calliper.

5.1.6Any shock can be used as long as it is direct fitment with no frame or linkage modification

5.1.7The ‘Pro-Am’ Fairing and belly pan are permitted

5.1.8Non-standard or modified carburettors are allowed

5.1.9YPVS conrods or crankshaft can be used

5.1.10Any ignition is allowed.

Section 5.2: RD350YPVS LC2, F1/N1, F2/N2, RD350R – 31K, 1UA

5.2.1Any OEM Yamaha twin opposing piston calliper, with an 83mm bolt pitch, that will fit without additional mounting brackets is allowed

5.2.2Allowance of four piston brake callipers with 83mm bolt spacing from the following models, to fit 350YPVS 31K or F2 forks, without any adapter plates.

Callipers must be from the following eligible models only. Master cylinder must remain 5/8‿ i.e. 16mm: FZR400 3TJ, TZR250 3MA, TZR250 3XV, R1-Z 250, Triumph TT600 and 595 series

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5.2.3Ignition systems can be a combination of eligible models or an aftermarket non programmable YPVS replacement

5.2.4Non-standard or modified carburettors are allowed

5.2.5TZR forks, wheels and brake may be fitted, along with the rear wheel, as long as the braking system conforms to TZR regulations. The YPVS rear swing arm must remain. The ‘Blue spot’ calliper may be used ONLY if the bike is fitted with TZR forks. See TZR rules for full definition of this calliper.

Section 5.3: RD350LC/YPVS Hybrid

Rules as RD250/350LC (section 4.2) with the following exception

5.3.1Ignition must be as per YPVS rules and the Powervalve system must be operational

Section 5.4: TZR250 1KT, 2MA

5.4.1Model 2XW-1 swinging arm, shock and linkages are permitted as these were officially fitted to later model 2MAs imported to the UK.

5.4.2Rear wheel can be replaced with a suitable 3.5in Yamaha wheel that will accept the standard spindle, cush drive and sprocket carrier

5.4.3We allow use of any OEM Yamaha MONOBLOC construction front calliper with 100mm bolt pitch that attaches directly to the fork leg without the need for an adaptor plate

5.4.4Carb needles and jets may be replaced. Carb bodies must be standard

5.4.5TZR/TDR wheel change eligibility

Below is a list of wheels that make up eligible options for front wheel variant for all models using the TZR250 forks. This list may change in the future as we find additional wheels that are suitable

Note the conditions are:

The original specification 12mm 1KT/2MA wheel spindle must be used

No adjustments to the forks or caliper can be undertaken to allow fitment

Standard wheel must be able to fit straight back into to setup using standard 2MA/1KT 12mm spacers, spindle and eligible caliper setup

The wheel must be off a Production Yamaha motorcycle

NOTE: All non – standard front wheels will require spindle size adjustment spacers, different wheel spacers and in some cases machining of the disc face. The machining specs listed below

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are only guidelines, wheels may need more or less machining of the disc face depending on origin. The only direct fit wheel is the OE 2.15 stock front


ID Number




2.75 x 17

TZR250 (2XT)


2.75 x 17

R1-Z 250 (3XC)


2.75 x 17

FZR250 (3LN model)


2.75 x 17



2.75 x 17



3.00 x 17

TZR250 (3ma & 3xv) **


3.00 x 17

FZR600 (3HE)

3.00 x 17

SZR660 **

Y-2 F-49

3.00 x 17



3.00 x 17

*The Brembo TZR125RR front wheel is possible to fit with the ‘Blue Spot’ Calliper but the wheel will be off set. The wheel will fit centrally with the standard calliper

**A modification to remove 4mm from the wheel is required

Section 5.5: TDR250 3CK, 2YK

Rules as TZR250 (section 4.4) with the following exceptions

5.5.1Footrest position may be altered by modifying or removing frame lugs, allowing fitment of aftermarket rear sets

5.5.2CDI and PV boxes from eligible TZR models are allowed

Section 6: Fuel

6.1Pump fuel only. Max 99RON, premixed with two-stroke oil if necessary. No octane boosters or other additives allowed

Section 7: Tyres

7.1Tyres: Any moulded treaded tyre. Wets are allowed. No slicks

Section 8: Technical inspection

8.1Random technical inspections may be carried out by YPMRC technical coordinators. Any potential rule infringements will be referred to the BMCRC

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Chief Technical Official for appropriate action under BMCRC/ACU regulations.

Section 9: Updates/queries

9.1Any changes made to the regulations will be decided under the control of the club coordinators and in some cases BMCRC Tech officials

9.2For any information concerning updates to or questions about the regulations, contact: Len Whalin – or Steve Higerty –

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