How The Pros Get The Power From The 2014 Yamaha YZ250F
CYPRESS, California, (February 5, 2014) – Yamalube Star Racing Yamaha’s Cooper Webb hasn’t exactly been a holeshot artist since he turned pro last summer. But during the first five rounds of his rookie season of AMA Supercross racing, he has grabbed quite a few holeshots between his heat races and 250cc main events.
While races aren’t won and lost off of the start line alone, starts are considered a reasonable indicator of engine performance.
With the 2014 Yamaha YZ250F’s revolutionary reverse-cylinder design, getting power out of a 250cc-class machine has never been easier or more effective.
For more on this, we talked to Yamalube Star Racing Yamaha’s engine guru, Brad Hoffman:
Power is at a premium in the 250 class. How much time have you spent working on the YZ250F power plant in general?
Brad Hoffman: Basically I’ve been with the team since 2003, so really been working on it since then.
So, you’ve been working on these engines basically since they were introduced...
Brad Hoffman: Yeah, pretty much.
This bike was definitely introduced pretty late in the year, and that had to cut into your development time quite a bit, didn’t it?
Brad Hoffman: Oh, yeah, for sure. Without the help of Yamaha – Bob Oliver and Dan Rambert – it would’ve been a much more difficult task, that’s for sure. We all worked on this together, and they were instrumental in making the gains we needed with the late introduction of the bike. We all put in a lot of hours in a short period of time to pull it together. We can’t thank them enough. And Keith McCarty over at Yamaha pushed really hard to make everyone come together, too, from Yamaha Japan, KYB, here at Star Racing, and Yamaha USA as well.
What was the biggest difference with trying to get more power out of this new engine?
Brad Hoffman: I mean, I don’t know if there’s really a huge difference in how you go about it, but the design of this engine is just so much more rewarding. You do the same amount of work to this engine and the gain is like twice [what you would gain with the previous engines]. If you did the same exact thing to the old engines that you did to this one, it’s a huge difference. And it’s not necessarily because of the four-valves, either...
So, is it the way that it brings in air that makes a huge difference there?
Brad Hoffman: Yeah, I think the reverse cylinder head allows the intake port so much of a straighter shot to the combustion chamber. That’s what makes it the best design that there is.
In the 250cc class nowadays, people push these engines really, really hard and they’re known not to last very long under that kind of strain. Is the ease that you can find power also helpful in keeping the engine reliable at the same time?
Brad Hoffman: Yeah... I mean, honestly, they don’t always become unreliable. I think a lot of it is just sometimes, if everything is not right in terms of parts design or fit, it could cause problems. I think, when you get everything just dialed, like doing the high-performance engines for motocross, they’re pretty reliable. They’re definitely not maybe as reliable as stock or whatnot, but durability and power should go hand-in-hand if everything is done right.
What do you consider to be the difference in the value of dyno-tuning as compared to track-tuning? And what’s the bigger priority?
Brad Hoffman: I feel like as long as you know what you’re looking for, and obviously we’ve been doing this a long time, the engine guy gets a feel for what he can get away with on the dyno and what he can’t. So, as long as you know what you’re looking for on the dyno, the dyno’s a “you can’t live without it” kind of thing. It’s definitely a good tool, but if you get carried away looking at one thing, like the peak number or something all day long, you could definitely go in the wrong direction. But as long as you know what you can sacrifice and what you can’t, the dyno is a really good tool.