This yr the KTM 250SX and the Husqvarna TC250 are fully new, and Yamaha invested within the YZ250 with new suspension and up to date styling simply two years in the past. That’s much more consideration than these bikes had acquired within the earlier 10 years mixed, plus there’s extra information on the horizon. All of it provides as much as one indisputable fact—two-strokes are again.
Our final full-250 two-stroke motocross shootout was in November of 2006. It handled six 2007 fashions, and the Yamaha emerged as the favourite. We didn’t comprehend it on the time, however that might be the final yr for a full class of two-strokes. Honda, Kawasaki after which lastly Suzuki simply gave up, making a local weather through which Yamaha didn’t must replace the YZ. Since then, it has offered simply nicely sufficient to justify its existence, receiving small modifications yearly. In 2015 Yamaha felt a rising tide of two-stroke curiosity and gave the YZ a brand new fork and new bodywork.
In case you’ve forgotten, the YZ250 is typical of the two-strokes that dominated the motocross world a technology in the past. It has a power-valve, case-reed motor with a five-speed gearbox. It has Yamaha’s first-generation aluminum body with a middle spine. The four-stroke frames had been fully completely different and went via a number of huge modifications, whereas the YZ250 remained the identical. The suspension, nevertheless, did change in these years, normally maintaining tempo with the four-strokes. At the moment, the bike has the most recent model of the KYB SSS fork. The burden hasn’t modified in various years; it’s 219 kilos with out gasoline.
KTM rocked the two-stroke world with a brand new line of two-strokes this yr. The motor within the 250SX is the progenitor of a complete household of engines that energy nearly all of the bikes produced by KTM in 2017. For that matter, it’s not that completely different from the not too long ago introduced EFI motor that may debut for 2018. This model has a 38mm Mikuni TX carb and a case reed. It doesn’t get the electrical begin that the off-road variations have, however it does have a stability shaft and the DDS diaphragm-spring clutch. That clutch is hydraulically actuated with a Brembo grasp cylinder.
The brand new body doesn’t look all that completely different from the earlier one, however it’s a contact shorter and has a steeper head angle. The rear suspension geometry is completely different. The shock itself is new, and the entrance finish has a WP AER 48 air fork. That final tidbit is the merchandise that actually introduced KTM followers alive this yr. The fork was really designed by engineers in Austria, whereas most earlier WP forks had been carry-overs (in most facets) from earlier Dutch merchandise. With out gasoline, the KTM weighs 211 kilos on the Dust Bike scale.
Each bike within the Husqvarna line has a counterpart within the KTM line. Some are nearly an identical; some are very completely different. The TC250 falls someplace in the midst of that continuum, having extra Husky-only components than the minis however not as many because the dual-sport bikes. All Husqvarnas have their very own bodywork, seat and graphics. A very powerful substantive change on the TC250 is the airbox, which is constructed into the subframe. This design goes again to the Husaberg days and has been refined over the past 5 years. At first the airbox was heavier and extra restrictive; now these points have been addressed. There are nonetheless variations in the best way the airbox impacts efficiency. Husqvarna additionally makes use of a Magura clutch grasp cylinder, D.I.D. Dust Star rims and a unique handlebar. The suspension, body and engine are all the identical because the KTM’s. At 211 kilos with out gasoline, so is the load.
THE POWER POINTS
As you’ve most likely heard by now, the motor within the new KTM is a rocket. So was the previous one. The KTM 250 has been the horsepower champion for a very long time within the 250 class, and that received’t change now. It makes extra energy before the Yamaha, then pulls tougher within the center and revs increased. If motocross races had been held on a dyno, the KTM would all the time win. The issue with all that energy is that it hits very exhausting. It tends to be all or nothing, and it’s a must to be on high of your sport to make use of all of it. For a very huge bounce, all the pieces is nice; you gasoline it exhausting and fly so far as you may. On medium-size jumps, it’s exhausting to manage the ability and never over-jump. In the event you up-shift and check out a taller gear, you threat having the exhausting hit come on the improper time.
Though the Husqvarna shares the identical motor, it has a milder hit. It nonetheless makes a ton of energy, however the TC250 is slightly simpler to deal with and appears to work higher at partial throttle openings. The one actual distinction is the airbox, so it nonetheless could be extra restrictive than the KTM’s. Neither bike is as straightforward to handle because the Yamaha. The YZ250 is a pet canine enjoying with two pit bulls. It’s enjoyable and fluffy, however it dangers getting eaten alive in sheer acceleration. Generally that’s a giant deal; generally it’s not. On tough tracks with poor traction, the Yamaha can put extra of its energy to the bottom. On a well-groomed observe with moist dust, the KTM and Husky are going to get away. Rider talent performs a giant half right here.
There are methods to melt the ability supply of the 2 Austrian bikes. The ability valve has optionally available springs in addition to an adjuster. The optionally available springs management how rapidly the valve opens. The adjuster acts on a unique spring and impacts when the ability valve opens. We discovered that the inventory preload (one flip in) is usually the smoothest hit if used with the usual spring (yellow). With the inexperienced spring, the preload may be turned counterclockwise as a lot as a half flip, and that combo tends to broaden the meaty a part of the powerband. You must watch out, although. Most settings solely make the hit tougher. Whenever you go to a brand new observe, all the pieces will appear completely different. It’s a lot simpler to make progress with jetting. The Mikuni carb is slightly lean on the underside and wealthy within the center. You possibly can go down the rabbit gap of looking for the proper needle, or you may name JD Jetting and get a equipment. JD doesn’t publish its needle specs, however the equipment has choices and good directions.
Making the Yamaha slightly extra pit bull-like can also be doable. Each FMF and Professional Circuit have pipes that get up the powerband. Then there’s port work. The Yamaha motor has been round so lengthy that the majority retailers have port specs, and getting extra energy isn’t that onerous. The catch right here is that the majority good porting specs will lead to a motorbike that wants race gasoline. Welcome to the world of trade-offs.
THE HANDLING GAP
One of many causes that Yamaha engineers didn’t do a lot to the YZ250 for over 10 years was as a result of they didn’t must. It dealt with so nicely that nothing else mattered. These days are gone. The brand new WP AER 48 air fork brings KTM and Husky out of the darkish ages. That is like giving cell telephones to historic Assyrians. Is it higher than the fork on the Yamaha? No, not in all functions. However, the truth that it has an infinitely adjustable spring charge makes it rather more versatile. In inventory type the Yamaha’s KYB fork is soft, plush and has glorious bottoming resistance. It’s, nevertheless, slightly too mushy for pure motocross. With inventory air strain (148 psi or 10.2 bar), the KTM and Husky forks can cope with huge hits and exhausting landings significantly better. Then, while you trip a smoother observe, you may drop the strain as little as 135 psi. You possibly can by no means fairly duplicate the Yamaha’s really feel for sheer consolation, however you may come very shut.
By way of total dealing with, all three bikes are glorious. The Yamaha is extra steady in tough stuff, whereas the KTM and Husky are extra agile. The Yamaha’s further weight is an element that the majority riders say they’ll really feel. That is much more noticeable beneath exhausting braking as a result of the KTM and Husky brakes are rather more highly effective than the Yamaha’s.
We’re undecided why Japanese two-strokes by no means got here with stability shafts. To be trustworthy, we didn’t assume it was mandatory till now. The KTM and Husky have such vibration-free motors that the Yamaha immediately feels shaky by comparability. Conversely, the Yamaha’s jetting is so excellent that the 2 Austrian bikes really feel sputtery. It’s all relative.
After 20 years of ready for Japan to get on the hydraulic-clutch bandwagon, we’ve given up. The Yamaha has the most effective clutch of any Japanese bike, however the clutches on the KTM and Husky are higher. They’ve glorious really feel and a lightweight pull, plus they arise nicely to abuse and overheating.
Within the face of so many compounding components, the Yamaha’s reign as a aggressive racer, even amongst two-strokes, is in severe doubt. These bikes are offered as closed-course competitors bikes, and utilizing that description as the only real standards, the YZ250 is outgunned. It’s slower, heavier and ill-equipped to race in opposition to the extra trendy KTM and Husky. Of these two, the Husqvarna’s slight variations give it sufficient of an edge to make it the official winner in the case of racing.
With all that settled, we’ve got to additionally level out that regardless that two-strokes are having fun with a giant revival, they nonetheless aren’t essentially getting used for racing. Most by no means see the observe and as an alternative are used for weekend rides and practice-track heroics. In that world, the Yamaha remains to be king. It’s a gentler, extra forgiving bike; in different phrases, it’s extra enjoyable. Frankly, it makes us hope that Yamaha doesn’t do one thing unthinkable. Like change it.