Enduro21 takes a closer look at the David Guarneri’s prototype Fantic XE 300 two-stroke, a truly unique machine in the 2022 EnduroGP World Championship paddock for the Fantic E50 Racing team.

While a fuel injected 300 2T is the mainstay of the hard enduro world, they are rarer on the timecard enduro tests, especially at the elite level. There are less 300cc two-strokes in the EnduroGP paddock than you think.

A few shining examples stand out of course; Brad Freeman on the 300 RR Beta, a new entry this year of Mikael Persson on the factory Husky TE300, plus there are a few 250 two-strokes kicking up the dirt – notably Theo Espinasse and Zach Pichon.

But the current trend in EnduroGP is a mixed bag of bikes stretching across the categories and while it has been refreshing in the last couple of years to see a wide range of model configurations hitting the top of the tests, the old favourite big 300 are less common. 

If you’re into big two-strokes, the current bike and rider at the top of the 2T EnduroGP tree is this Fantic Factory E50 Racing team prepared XE 300 ridden by Davide Guarneri who lead the world championship as of round two.

You are looking at a rare beast, a true prototype machine which you can’t currently buy. Fantic say we will be able to buy one, just as soon as Guarneri has finished the real world R&D process taking place in the is year’s Enduro World Championship.

And that is why Enduro21 was so keen to get the low-down on this rare beast while it is around. We caught up with Guarneri’s chief mechanic, Emilio Comotti, in the EnduroGP paddock to try and unearth some of details about this saucy prototype…

Let’s talk about the engine

The is a rare beast indeed, a prototype built upon the Yamaha YZ 250 two-stroke with Fantic development ‘on top’, literally. As you’d expect, and unlike a lot of the Pro bikes we focus on, there’s a lot going on inside Guarneri’s engine which the team and Fantic are tight-lipped about. 

What we can say is this is Fantic’s own cylinder, two-ring piston, barrel and cylinder head. We don’t have measurements to quote but it is running medium compression to suit enduro, rather than an MX high-comp head.

On that note, there’s another 300 2T Fantic racing in EnduroGP this season. Fantic D’arpa Team’s Albin Norrbin is racing one but that bike is basically the XX 250 motocross model with an Athena 300 kit, enduro bodywork and lights. Guarneri’s bike is a factory special.

Lower down in the engine department, the crank and bottom-end engine internals are a bit of a secret too – development factory parts they tell us. But we did learn they run different weights on the flywheel depending on the conditions – at this dry and hard packed race that was pretty light and free-revving.

38mm Keihin carb

The 38mm Keihin carburettor is no stranger to a dirt bike. Components across the Fantic range of enduro bikes are cherry picked for quality and performance before budget.

This Keihin has a setting specific for the prototype 300 and to Davide’s specification. The reeds themselves are also a development part so not available, “at the moment.”

This is clearly where Davide’s 300 will differ from the production bike which will have the EFi system as mentioned above plus an electric starter also built in.

Although this bike is very much a Fantic project, Minarelli (and Yamaha) are all part of the same group and as such are working together on a 300 production bike.

Fantic and two-stroke fans might remember we poked our noses into Motor Minarelli’s 300cc injected two-stroke prototype engine revealed at the 2021 EICMA motorcycle show. There’s a difference you’ll have spotted already, this E50 Racing Fantic runs a 38mm Keihin carburettor specific for the bike – the fuel injected bike will come later.

As they say, racing improves the breed but that is ultimately true with Fantic who have progressively increased their production bike range by first going racing.

Non-starter?

You’ll spot the kickstarter on the side but at the moment, this prototype is truly old-school and has no electric starter.

The ECU is Fantic’s own, based on existing development for the 250 model but still unique for the 300. There are two map options for Davide (switchable at the handlebars): full power and a softer mode for slicker conditions or if the extreme test is really technical.

Wiring in general is all standard, or as you’ll find on other Fantic models with a stator to fit lighting etc.

The team run a Rekluse clutch cover which is simply a stronger outer case and they are running same gear oil quantity as standard on a YZ250X. The gearbox is the same set of parts as you will find in a YZ X also, so five gears.

A lot of the base for Davide’s bike are from the donor Yamaha and that includes the radiators which are standard without a fan.

The o-ring Regina chain is running on PBR sprockets and Emilio tells us Guarneri runs 14-49 gearing “all the time, no change.”

Silencer and exhausts system are made by Fantic (developed from standard from 250 2 stroke Fantic) and based on the standard 250 parts but modified for the 300 so, like the rest of the bike, not yet available to buy.

Take a walk around the bike…

The engine is the focus here but Emilio walks us around the rest of the bike. Overall it’s very much a stock bike as you’d buy from Fantic. No changes to the original main frame, subframe or swingarm from the original parts coming from Yamaha in Japan.

The common chassis across models means all Fantic’s two-stroke enduro range run the same eight litre fuel tanks.

Standard rims house Metzeler tyres and mousses all round with different hard/medium/soft options depending on the race and terrain. They run a Marchald air filter, which we must admit is a new name for us. They are a common upgrade in Italy on Lambrettas apparently.

Guarneri is using Newfren discs front (270mm) and rear (240mm) with Newfren pads. The team retain the standard Nissin master cylinders front and rear also.

KYB forks are the standard equipment on all of Fantic’s enduro models and Davide’s 48mm front KYB forks are “softer in the first part of the stroke but progressively hard”. The same setting is in the rear shock plus it is running standard suspension linkage.

Geko Special Parts are littered around the E50 race bike from the triple clamps (with stock off-set of 25mm), axle pullers, plus the wider than stock and stronger footpegs – riding position is the same as standard. Davide sits on a Selle Dalla Valle seat cover with “nothing special” about the seat foam shape.

Crosspro supply the skid plates for the team with a linkage protection while Racetech provides the handguards and Domino handlebar, which a similar bend to stock (it’s the medium height from Domino) and the grips which are medium.

Photo Credit: Future7Media | Andrea Belluschi