This year marks the end of the two-stroke era in grand prix roadracing, as the 125cc class transitioned to Moto3, using four-stroke, 250cc machines. Ironically, as Moto2 uses a production-based Honda engine and MotoGP is likewise threatened to be an all-CRT class using production engines in the future, Moto3 may be the only class using prototype engines going forward. Alternatively, the MotoGP rules may end up being similar to those for Moto3 — prototype engines but commercially available and with strict controls and a claiming rule.
The Honda MR03 Moto3 engine...
The Honda MR03 Moto3 engine has a rearward-canted cylinder and reversed head, with the intake in front and the exhaust exiting out the rear. This arrangement is said to minimize the effects of the additional weight compared to a 125cc two-stroke. Honda claims 47.6 horsepower at 13,000 rpm and 20.7 ft-lb of torque at 10,500 rpm for the engine.
While Honda does manufacture...
While Honda does manufacture the NSF250R for Moto3, most teams opt to use aftermarket chassis from FTR, Suter, FGR or TSR. The NSF’s front and rear suspension units are similar to those used on the RS125, and wheels are identical. The riding position is also similar to the RS125’s, with the aim of easing the transition for riders from 125cc two-strokes to the heavier four-stroke.
The FTR chassis is by far...
The FTR chassis is by far the most popular choice for Honda teams, with two teams switching from the standard Honda frame to the British built frame and bringing the total to 10 FTR Hondas in Le Mans. Spanish rider Maverick Vi�ales had won one round and was second in points after four events, while Frenchman Louis Rossi on another FTR Honda won at his home event in Le Mans.
The factory KTM Moto3 machine (left) was designed in-house and features a steel tube frame. After four rounds in the 2012 championship, German rider Sandro Cortese led the championship on one of the five Red Bull Ajo factory machines entered in the series, with one victory. Five riders are entered on Kalex-KTM machines (right), which use the KTM M32 engine but in chassis designed and manufactured at Kalex Engineering in Germany. Spaniard Luis Salom was in third place in the championship points after four rounds on the RW Racing GP Kalex-KTM.
The new rules for Moto3 require four-stroke engines with an 81mm bore (identical to the maximum allowable in MotoGP). One chain must be used in the valvetrain (no all-gear systems) and the ECU is a spec item supplied by Dell’Orto that limits maximum engine speed to 14,000 rpm. Pneumatic valve actuation is not allowed. The throttle body can only have one butterfly and it must be controlled by the rider — no ride-by-wire system. Only one alternate set of transmission ratios and one alternate primary gear ratio are allowed.
Indian company Mahindra builds its MGP30 in-house using a steel tube frame, which makes it easier for the team to make modifications in early development. The Mahindra's engine is a joint project with Italian company Oral Engineering, and the engine was designed to also be used in existing Aprilia RSV 125 chassis. The Ambrogio NExt Racing team began the year with this combination, but switched to Suter Hondas beginning with the French round.
Strict controls on the engine and parts availability ensure fair competition. An engine manufacturer must be able to provide a minimum supply of engines and spare parts for 15 riders, and engines can be claimed for €12,000 euros (about $15,000). Spare parts must be provided and priced within market values, with no options that are only available to a select few — everyone has access to everything on the published list, and only those parts are allowed to be used. Aftermarket parts are allowed, but the engine manufacturer cannot be involved and the parts are subject to the same minimum availability restrictions as stock parts.
The all-Italian Ioda Racing Moto3 entry uses a aluminum beam frame and an Emir engine built in collaboration with Robby Motor Engineering, an aftermarket company that was involved in development of the Benelli three-cylinder engine.
KTM’s M32 motor was designed...
KTM’s M32 motor was designed by engineer Kurt Trieb, who also designed the company’s V-four MotoGP engine.
To date, four engines have been approved for use by the FIM — Honda, KTM, Oral Engineering and Emir — and nine manufacturers have developed chassis packages for those engines. Like Moto2, Dunlop supplies spec tires for the Moto3 class, and spec fuel and oil supplied by Eni must be used. Unlike Moto2 and MotoGP, the minimum weight of 148kg (326 pounds) includes bike and rider. Although stock or approved engine parts must be used, those parts can be modified or machined freely, allowing some freedom for creative engine builders. Chassis design and manufacture is open, and this is where the class has generated some interesting variety — and perhaps a glimpse into the future of MotoGP. SR