Trial Comparison: 2-stroke vs. 4-stroke

trend in the trial market has made it very clear that the attempted coup d’état imposed by valve engine models in 2005 has remained just that, an attempt. Throughout these little more than five years we have witnessed a situation of uncertainty, where it seemed that the days of two-stroke trial engines were numbered and the future lay in the “ecological” 4T.

Between the “boom” and the novelty, practically all trial brands opted to market a 4T version. Some, like Montesa, decided to bury forever a winning and well-accepted bike like the Cota 315R; others, such as Sherco, Beta and Scorpa opted for the same path, which is to work on both fronts, although adopting very different paths. Of course, no trial brand sprouted from scratch betting on the 4T, something that is currently happening with the 2T in factories such as Ossa, Fantic and surely JTG.

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In trial, within thetop competition, all have abandoned their commitment to the 4T, except Montesa, who remains strong with the Cota 4RT at the top thanks to the  hands of an incredible Toni Bou. Cabestany is facing his second consecutive season after his return to the 2.9 2T, although he is a rider who fit well with the powerful 3.2 4T. Scorpa left the top trial competition years ago and only the tail ends of Yamaha in Japan with the great Kuroyama remain. Beta made a feint of betting on the 4T in the trial world championship with Pascuet, but the truth is that the Italian brand has always bet mainly on the 2T.

Against this backdrop, the market has undergone a progressive, but very clear, change of trend towards Q2, strengthened by the high demand for these engines and the appearance of new technical solutions associated with this configuration, as is the case of the injection proposed by Ossa. In any case, this stage has also struck a chord with many fans, who now only want 4-stroke versions for their smoothness, ease of use and durability.

For this report we have selected the two models more representative of both configurations: the Montesa Cota 4RT – the standard version of the one used by Toni Bou – and the Gas Gas TXT Pro – the standard version of the one used by Adam Raga. We’re going to reveal the pros and cons of each setup, so that each fan can draw their own conclusions. Don’t forget that you can comment on the article at the end of it.

Two Options, One Direction

To better understand the differences between the two models, we must go back to their origins. Back in 2001, a very young Adam Raga premiered a prototype of Gas Gas in competition that would soon reach the assembly lines under the pseudonym “TXT Pro”. Its daring geometries made it the center of all eyes, praise and some criticism. The beginnings were hard and even when it soon began to win races, it paid dearly for its immaturity and ended up emerging as a tremendously competitive trial bike, but with a lot to polish, as has been demonstrated throughout these ten years.

If the TXT Pro was built based on a racing prototype, in Montesa, with the Cota 4RT, the opposite happened. Shortly after Takahisa Fujinami scored his only world title, 2004, a On the back of a Cota 315R, Montesa received a clear order from its parent company, Honda: bury that winning bike forever and start a new journey dominated by four-stroke cycle mechanics.

When Montesa launched the 4RT, it had been almost two decades since a valve engine had been mounted on a trial bike. The cardiac and versatile two-stroke mechanics had always proved to be the most logical choice for a truly unique specialty. The four-strokes needed, first of all, to create trust and culture among trial users.

Text: David Quer / Photos: DQ & PS / Action: David and Chema Quer

Electronic Fuel Injection

In addition, with the Cota 4RT, electronic injection came to trials. Regardless of its performance, the fact is that the wide range of possibilities of this food system
deep lethargy. The possibilities to regulate the behavior of the motorcycle with the injection are endless, although in the production models these electronics are not so complex. The system has multiple sensors that allow a perfect adjustment of the power supply depending on the weather conditions, something that motorcycles such as the Gas Gas, is achieved by manually manipulating the carburetion parameters.

The injection is, in large part, to blame for the fact that the behaviours of both trials are so heterogeneous. In general terms, the answer seems more precise than with the carburetor, however the latter works better at revs below two thousand revolutions. The only point where both mechanics converge is, basically, the displacement, although Gas Gas also offers versions with greater displacement, specifically 272 and 294 cc. For the Montesa, there are cubicage augmentation kits marketed by the auxiliary industry.

Character and versatility

Montesa conceived the Cota 4RT with the average user in mind. That explains why the obsession of the engineers is not to offer a revolutionary product in terms of lightness, but in terms of quality in components and technology. The 4RT loses court to its opponent as the terrain becomes more selective and the room for maneuver is smaller. The cause of this counterpoint is a marked overweight that is around ten kilos -77.6 for the 4RT compared to 68 for the TXT-. However, thanks to an even-handed weight distribution and a brilliant suspension team, the Montesa is more capable of high-level trial than you might expect.

The reason for this lies in the fact that the Cota combines an elastic engine with good torque, a generously long gear ratio and a rather smooth suspension setting. If, on the other hand, we observe more radical geometries, a pointed engine and fast suspensions, we will begin to perceive an unmistakable smell of mixed gasoline that leads us to the TXT “Pro”.

Situating ourselves in the scenario that interests us, the zones, we can see that the same obstacle has never seemed so different. Although the pilot’s technique is obviously decisive, in order to overcome difficulties successfully, it is necessary to know, first of all, the particularities of each model. For more than two decades, we have been applying the trial story of “the higher the revolution, the more power”. Seen in this way, it seemed that the culture of elastic valve motors would have no place in the context of this specialty, however, electronics allow us to conceive as realities what previously seemed like a utopia.

If we analyze the graphs that both engines draw on a dyno, we can draw some very interesting conclusions. First of all, the Japanese engine reaches its maximum performance shortly before seven thousand revolutions, and from this point on it continues to increase in revs, but with the useful power progressively decreasing. When it comes to torque, the 4RT has a flatter and more consistent graph, while its rival delivers better values in the mid-revs. This explains why the four-stroke engine offers a good response from very low ranges although, despite withstanding the overrevs very well, in extreme situations it longs for the rage that a 2-stroke exudes.

These premises can also be translated into sensations. The Cota is a very effective bike in the zones, but it doesn’t get along well with strong accelerations or sudden changes of pace. He asks to play more with inertia; In short, to roll within the zone and be accompanied with the gas fist. Driving in this way is possible, in addition to taking advantage of the engine’s brightest revs, to minimize the effects of very pronounced engine braking. La Gas Gas, on the other hand, is much more intuitive. In absolute terms, it has greater capacity than its rival and performs better in extreme situations, but it requires greater attention from the rider, especially in strong starts.

Counterpoints

It is enough to ride a few minutes with each bike to realize that the gear ratios are also completely different. This is much longer in the case of the Montesa. It is a motorcycle that, for the most part, asks to be ridden within the zones in first gear. This point contributes to making the Cota 4RT more difficult to drive than its rival. The bike is very loose and, when it comes to very technical areas, it forces you to play a lot with the clutch to get it through the
Drawn. This point also makes driving more demanding. The solution? Two more teeth in the crown, i.e. 43. The improvement is remarkable, basically because the rest of the ratios are used more and the bike does not run as much in the sections. The only counterpoint is that engine braking is also felt to a greater extent.

The Gas Gas is generally easier to drive, especially when compared at first contact. The staggering of this gearbox, rougher and drier to the touch than that of its rival, is perfect for combining purely recreational use with competition.   

More equality

thermodynamics , the Gas Gas has a certain advantage, the Montesa It closes the gap again thanks to an outstanding suspension system.

It inherits the scheme of the defunct Cota 315R, which revolutionized the sector with a double-beam chassis built in aluminum and a set of unrivaled suspensions, signed by Showa. This trend continues, although the fruitful work of the Gas Gas engineers with the evolutions of a scrupulously noble and stable tubular chassis, make the TXT a benchmark in the 2011 panorama.

At the front, equality is maximum. Both forks are at an extraordinary level, and, although the morons are quite even, each one has a completely different personality. La Marzocchi of the “GG” is, thanks to its aluminum bars, much lighter, a detail that has a positive impact on the ride, making the Girona bike dynamic, playful and easy to place. While these attributes might well cater to Montesa’s Showa fork, the heavier weight of the set curbs its slights. It doesn’t invite you to be piloted with the wheel in the air as much as its rival, but it prints an outstanding dose of stability and poise, literally welding the front end to the chosen line.

Conclusions

In short, these are two disparate models whose conceptions are perfectly valid to please the most exquisite, even if they employ alternative ways. The effectiveness of both concepts depends, first of all, on the scenario and the type of use we are going to give them. Thus, Montesa proposes a less radical and versatile concept, dominated by components of the highest quality and a more than proven reliability. Its aptitudes within the zones are very broad, but it requires a longer period of adaptation to know its mechanical particularities and make the most of the performance. In the long run it’s just as fun and rewarding as a Q2 or more.

The TXT“Pro” has multiple attributes that make it the winner of the duel: it is lighter, its pure performance is greater, the chassis is at an optimal level, mechanically it is simpler, but it requires intensive maintenance so that all the components work like clockwork. Last but not least, its price is around twenty percent below the Montesa.

Don’t forget that you can comment on the report in this article. In addition, this topic coincides with our poll of the week, which you can find in the “home” of the website, at the bottom: What type of engine do you prefer to practice Trial?

You will find the photo gallery of the comparison below the technical sheet. 

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TECHNICAL

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