The long-awaited rules for the replacement of the 125cc class were announced at Valencia on Saturday, with the details finalized for the 250cc four-stroke formula. The rules contain few surprises from the information that has leaked out over the past few months, with the thought process behind it very clear: a lot of technical regulations have been imposed to avoid the costs from spiraling out of control.
The most important technical restrictions are in the engine, the fuel supply and ECU. The 250cc four-stroke engine will have a maximum bore of 81mm - the same diameter as the 1000cc MotoGP bikes from 2012 - and a hard rev limit of 14,000 rpm. In addition, the engines will have only 4 valves, with the camshaft driven by a chain, and variable valve timing or exhaust valves banned. Fuel pressure will be limited to 5 Bar, and a standard fuel spec will be imposed. Only two injectors will be allowed, and variable-length inlet tracts (as seen on several street bikes nowadays) are also banned. Most interesting of all is that the rules stipulate that the throttle valve must be operated directly by mechanical means only from the rider's wrist.
A spec ECU will be enforced, as well as a standard data logger, to avoid extra data inputs to be used for tweaking the electronics. No hardware or software changes other than software maps will be allowed, and to prevent cheating, the Technical Director will be allowed to demand that the teams switch out one ECU for another at any time.
Gearboxes will be more adjustable, with two separate ratios allowed for each of the six permitted gears, but they will not be as infinitely adjustable as the cassette-type gearboxes currently in use. The minimum weight (currently 136kg combined with rider and bike) will be increased to 148kg, but most of that will go into the extra weight in the engine.
Each team will be allowed only 8 engines a season, with engines being sealed between races. An interesting change from the MotoGP regulations is that the seals will not be applied to the cam covers, allowing valves to be adjusted - and possibly also modified, and different cams fitted - on a sealed engine.
Perhaps the most significant area of control is in the engine supply, however. Engines must be sold for under 12,000 euros, and a published manufacturer's spares list with prices must also be submitted, to prevent the obvious ruse of selling an engine for 12,000 euros, and then a separate race kit for 90,000 euros to selected teams. All spares must be available at a reasonable price to all the teams. And each manufacturer must be willing to supply at least 15 riders with engines and spares for the same price.
The glaring weakness of the engine supply rules is the stipulation that the engine price limits and spares price limits only apply to manufacturers. There does not appear to be a limit to development being carried out separately by either the teams or an individual engineering company. And so the 90,000 euro race kit may not be available from the manufacturer, but it would appear to be available through independent engineering shops. Whether this loophole will be exploited or closed remains to be seen.
The Spanish website Motoworld.es estimates that the maximum power that engines produced under these regulations would be in the region of 50 horsepower. Actual numbers may well turn out to be lower, as an engine with an 81mm bore would probably prove to be too peaky in producing those 50 hp, and a longer stroke, lower-powered engine may well produce faster lap times. So far, all of the Moto3 bikes presented - or rumored - have followed MX bore and stroke dimensions, with bores closer to 75 mm than 81. A longer stroke should produce a smoother, more rideable engine, with a wider spread of power.
Below is the full text of the regulations as produced by the Grand Prix Commission:
- 4-stroke reciprocating piston engines only.
- Engine capacity: maximum 250cc.
- Single cylinder only.
- Maximum bore size: 81mm. No oval pistons.
- Engines must be normally aspirated. No turbo-charging, no super-charging.
- Crankshaft speed limited to maximum: 14,000 rpm.*
- Maximum of 1 ignition driver.*
- Maximum of 4 valves.
- Pneumatic and/or hydraulic valve systems are not permitted.
- Valves timing system drive must be by chain.
- Variable valve timing and/or variable valve opening systems are not permitted.
- The engine is defined as the complete engine including intake system (throttle body, injectors), and one complete transmission.
- The maximum price of the engine must not exceed 12,000 Euro. No optional parts or service contracts may be used to circumvent this price limit.
- Each engine manufacturer must undertake to supply sufficient engines and spare parts to supply minimum 15 riders per season, if requested.
- Each engine manufacturer must submit a spare parts price and lead-time list for the season for approval by the Organiser, and may not charge more than these published prices. Approval is based on the prices and lead-times being in line with current market norms for these parts and technologies.
- In the event of engine updates or upgraded parts being developed, these must be made available to all customers at the same time, and respecting the price limits described above.
Inlet & Fuel System
- Variable-length inlet tract systems are not permitted.
- Only one throttle control valve is permitted, which must be controlled exclusively by mechanical means (eg. cable) operated by the rider only. No other moving devices (except injectors) are permitted in the inlet tract before the engine intake valve. No interruption of the mechanical connection between the rider’s input and the throttle is allowed.
- Idle speed adjustment by means of an air bypass system, controlled by the ECU is allowed.*
- Fuel injectors must be located upstream of the engine intake valves.
- Maximum of 2 fuel injectors and 2 independent fuel injector drivers.*
- Fuel pressure must not exceed 5.0 bar.
- Other than engine sump breather gases, only air or air/fuel mixture is permitted in the inlet tract and combustion chamber.
- Fuel must comply with the FIM “Moto3” specification (tba).
- Variable length exhaust systems are not permitted.
- Noise limit will be a maximum of 115 dB/A, measured in a static test.
- No moving parts (e.g. valves, baffles…) are allowed in the exhaust system.
- A maximum of 6 gearbox speeds is permitted.
- A maximum of 2 alternate gear ratios for each gearbox speed, and 2 alternate ratios for the primary drive gear is permitted. Teams will be required to declare the gearbox ratios for each gear used at the beginning of the season.
- Electro-mechanical or electro-hydraulic clutch actuating systems are not permitted.
Ignition, Electronics & Data-Logging
- Only the ignition/fuel injection control units (ECU) approved by the series Organiser are allowed.
- This official ECU will include an engine rpm limiter.
- Only the standard Data Logger system approved by the series Organiser may be used.
This ECU must remain unmodified in hardware and software, as delivered by the Organiser. The only permitted changes are the setting (tuning) options included in the software.
The Technical Director may require the team to change the ECU on any machine for another standard one at any time.
* All the parameters identified by this symbol are set/controlled via the above mentioned ECU.
- Chassis must be a prototype, the design and construction of which is free within the constraints of the FIM Grand Prix Technical Regulations.
- Minimum total weight of Motorcycle + Rider: 148kg
- Brake discs must be made from an iron-based alloy.
- Suspension systems must be of a conventional passive, mechanical type. Active and semi-active suspension systems and/or electronic control of any aspect of the suspension and ride height is not permitted. Springing must be by means of coil springs made of Iron-based alloys.
Wheels & Tyres
- The only materials allowed for the wheels rims are Mg and Al alloys.
- The only permitted wheel rim sizes are:
- Front, 2.50” x 17”
- Rear, 3.50” x 17”
- The number and specification of tyres allocated to each rider per event will be controlled.
- Only tyres from the Official Supplier may be used.
Materials & Construction
- Construction materials must comply with Article 2.7.10 of the FIM Grand Prix regulations.
- Camshafts, crankshafts, piston pins must be made from Iron-based alloys.
- Engine crankcases, cylinder blocks and cylinder heads must be made from cast aluminium alloys.
- Pistons must be made from an aluminium alloy.
- Connecting rods, valves and valve springs must be made from either Iron-based or Titanium-based alloys.
- “X-based alloy” means the element X (e.g. Fe, for iron-based alloy) must be the most abundant element in the alloy, on a % w/w basis.
- Number of machines: the team can scrutineer only one motorcycle per rider.
- Number of engines: a maximum of 8 engines per rider may be used during all Grand Prix race events comprising the season. A rebuilt engine will be counted as a new engine.
- Teams will be required to register engines at Technical Control on the day before the first practice at each event. Such registered engines will be sealed (excluding cam cover, transmission if applicable) and seals may not be removed except under supervision of the Technical Director. Only sealed and registered engines may be used on track at Grand Prix race events. An engine presented for Technical Control without intact seals will be counted as a new engine.
- Apart from the above regulations, all other construction criteria, dimensions and specifications are as per the FIM Grand Prix Regulations.