Spoken Wheel: Moto3 & Four-Stroke Singles

November 24, 2010
Gavin Trippe
Gavin Trippe
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Gavin Trippe is an AMA Hall of Fame member and racing promoter. Currently Mr. Trippe organizes the Monterey Classic Bike Auction and relentlessly campaigns for a new road racing class based off 450 motocrossers. In his spare time, the industry insider pens his serial column – The Spoken Wheel.

This 2009 concept Honda was built for the AMA Pro using a standard Motocross frame  subframe  swing arm and forks modified by RaceTech for the proposed F-450 National series.
This concept Honda was built for the proposed F-450 National series using a standard Motocross frame, subframe, swing arm and forks. The idea was rejected, however, in favor of the Harley/Vance and Hines 1200 series.

Moto3 – the rebirth of the Four-Stroke Single?
Manx Norton’s, AJS 7Rs now Motocross on asphalt?
Size matters and the significance of 81mm!

With a gnashing of teeth, wringing of hands and lots of wailing at the wall, right or wrong, the two-stroke finally bows out with the news that Dorna, aka MotoGP, have decided that in 2012, the 125cc class will become Moto3, with the suggestion that this perennial class be replaced with 250cc single cylinder four strokes. Curiously enough the call is for brand new spec built race engines from any supplier with a maximum cost of around $16,000 per motor. Why, one asks? Read on!

Moto3 2012: Engines must be four-stroke Singles. Bore size is limited to 81mm and capacity capped at 250cc, max rpm @ 14,000. Riders will be limited to eight total engines for the entire season. An interesting spec feature of the series will be in the electronics, with spec ECU required. Unlike the Moto2 series in 2010, the Moto3 class will not use a spec engine, but will be open to all manufacturers, provided they not exceed a 12,000 Euro ($16,000 cost limitation). The engine supplier must also be capable of delivering engines to a minimum of 15 competitors, if requested, with no special engines for ‘factory’ riders. Like the Moto2 class, the new Moto3 series will run prototype chassis. Teams must adhere to a minimum weight limit of 148 kg (326 pounds), which accounts for both motorcycle and rider. This doesn’t account for the running chassis etc, which could boost the total individual unit to over $30,000 plus spare engines etc.

2009 Kawasaki KX 450 F-450
2009 Kawasaki KX 450 F-450

WHY? The obvious question is “why bother?” Trying to persuade manufactures in this economy to build and develop purpose-built, brand-new ‘screamer’ 250’s from scratch verges on insanity. For the sake of an extra 15 pounds per unit, they could simply open the series up to a ‘modified’ version of the standard workhorse 450cc pure race engine that currently power the world of motocross, dirt track, supermoto and enduro, of which there are least TEN different manufactured versions. The probable end cost of such a 450 racer would be the same as the price of a single 250cc Moto3 motor yet to be built, and with the same power/weight ratio and an abundant parts supply.

Bigger capacity, lower RPM, more torque and available at a fraction of the cost. Modifications to such a 450 race engine would be the option of gearbox internals up to six speeds, with constraints on materials and use of standard castings. My sources reckon that the new 250 GP motor would come in at around 50 horsepower, whereas a modified stock based 450 would run at close to 70 horsepower. The 450 would be slower revving, less costly and readily available with the biggest advantage being in terms of torque, something seriously lacking in the 125cc two-strokes and obviously much stouter than the proposed 250cc Single. Another benefit of the 450-based racebike would be teams using units other than the big four, such as KTMHusqvarna and BMW, lending brand recognition and support from dealers, distributors and fan affiliation. Currently there is no brand ID, Moto2 being Honda motors in special chassis.

81MM: So here is the rub and the significance of the dreaded 81mm rule. Simply put, the 1000cc formula for the new MotoGP class limit in 2012 that supersedes the misguided switch from the old 990s to the current 800s is that the maximum cylinder bore is the same for both! The new MotoGP four cylinder for 2012 is 81mm, the same as the new proposed 250 Moto3!

So there we have it. Not the obvious solution to run readily available, but modified, production 450s, but appearing to appease the big players in developing the new generation of their MotoGP engines, by having the new 250 as a slave unit version, being the same as one pot off the new MotoGP 1000cc motors. For those who don’t get it, 1000cc divided by four equals 250cc, both with the same matching 81mm maximum bore. I see the logic but don’t understand the math in terms of trying to grow access to more potential sponsors, racers and new teams.

KTMs prototype 450 RC4 Single motocross motor shoehorned into a KTM 250 MotoGP frame. This just shows the potential of production motocross units as road race machines.
KTM’s prototype 450 RC4 Single motocross motor shoehorned into a KTM 250 MotoGP frame.

It’s the old adage of planting many acorns to grow a single oak tree, the sport needing to cast a bigger net outside of Spain and Europe by creating a larger pool of teams and players. When Michael Schumacher, an avid motorcycle fan, was asked by someone where the next Formula 1 Champion may come from, he replied succinctly, “I don’t know, but not likely to surface from the current system. He’s probably still driving a cab somewhere in Brazil!”

Obviously I have a personal dog in this fight, having implored AMA Pro to take the initiative to create a new class this year for young riders using modified 450 Motocross bikes all to no avail. The stillborn F-450 was superseded by a spectacular decision to change their minds, despite announcing their intent at the 2009 MotoGP at Laguna, but punt and introduce the less than spectacular Harley/Vance and Hines 1200cc class this year, featuring a total of eight bikes on the grid! Presumably sponsorship trumps logic.

So even if MotoGP insiders decide to make the new rules from the pit lane outwards, rather than the Grandstand inwards and prevail with this prototype 250cc formula, it will hopefully move young aspiring racers and the alphabet Club promoters, to pursue the concept of lightweight single-cylinder racing as the new grass roots formula and a racing stepping stone prior to youngsters wrestling 500-pound 600cc sportbikes. Affordability and a true multi-brand class with the scepter of more than a chosen few affording to ultimately go road racing is the prize.

The four-stroke Singles, both 250 and 450, are the gold standard for the future of motorcycle racing by growing the grass roots of the sport exponentially, just like motocross has as a shining example. That would be a good thing.

Boy Racers: So there we have it, the potential return of purpose-built racers, not deconstructed street versions unseen since the post World War II-era of the Norton Manx 500cc Singles, the aptly named AJS 7R “BOY RACER” and the trusty BSA Gold Star, the likes of which Mike Hailwood cut their teeth on, just going to the local dealer, buying one to go racing.

AMA Young Guns Champion  Joey Pascarella  learning his craft on one of the Honda 450s. Other young stars to have ridden these bikes are Elena Myers  Benny Solis and this years Daytona winner  Tyler Odom  who won the AMA Number 1 plate on a 450 at Mid Ohio in 2008.
AMA Young Guns Champion, Joey Pascarella (above), learning his craft on one of the Honda 450’s. Other young stars to have ridden these bikes are Elena Myers, Benny Solis and this year’s Daytona winner, Tyler Odom.

The beauty of motorcycle racing is the simplicity of it all… two wheels, two square inches of rubber in contact with the asphalt, the right gyro up your butt and a strong and brave right wrist. You can’t fall off a car but you can a bike, which makes motorcycles so much more intriguing and accessible. The current 450 four-stroke Single is a shining example for the potential to get young racers with a minimal budget to secure the future of the sport and see if they have what it takes.

One last thought. The current 125 road racers are too small in many ways these days of growing 21st century teens. You think Ben Spies could fit on a 125cc chassis, the same size that will be the new 250 Moto3? This is the conundrum that plagues modern rule making that the gnomes of government ignore in their infinite wisdom.

Size does matter: it’s not just size in terms of capacity that matters as outlined previously in terms of cost; it’s also chassis that is a huge factor that makes the difference between this young class being inclusionary, rather than exclusionary. The Mandate that you have to be 5-feet tall and 98 pounds wet, effectively bars much of the potential reach and search for new talent in the current generation of lads, whose granddads were likely a good six inches shorter generationally! So let’s not leave that future Rossi to ‘ear hole’ the streets of Buenos Aires in a taxi in MSC parlance, make the rules suit modern needs financially and generationally – more acorns, more and bigger oak trees! More Rossi’s!

Like the idea of a 450 Single class in AMA Pro Racing? Visit www.ipetitions.com/petition/f450/ to make your opinion known.