Friday Feature: Factory R & D

Back in 1998, Ken Leybourne invented the first high-performance bolt-on accelerator pump in an effort to improve throttle response on Yamaha’s revolutionary YZ400F. Today, Ken’s company—Factory R & D—continues to produce high-quality aftermarket components, as well as suspension and engine modification services.

Ken and the rest of the Factory R & D crew spend a lot of their time at local tracks testing their latest designs, but we were able to catch up with him at their Southern California shop (a.k.a. laboratory) to bust out a quick interview. Here’s what Ken had to say…

As always, Ken, we like to start our Friday Feature interview with a quick history lesson about the company. Fill us in on how you got started.

I have a degree in engineering and started by developing bicycle components a long time ago, but when I got out of school I was working in the auto racing industry and designing parts for those. I’ve loved motorcycles since I was twelve years old, but when I was working in auto racing I had to back off from them for a few years. They frowned on motorcycles because if you got hurt, you couldn’t do your job. Auto racing is an intense industry; they don’t want to see you missing much shop time.

From there I worked for an off-road racing team for a while and then left that and finally got back into motorcycles again. Actually, I had to have knee surgery and while I was recovering I was riding a bicycle and started making components for it. From there it was an easy transition into making motorcycle components. I saw little gaps that I thought I called fill, and just started there.

In ’98 I went full bore into motorcycles; the year Yamaha came out with the YZ400F. It had some serious carburetor problems and that’s when I came up with the P38 lightning.

The P-38 Lightning accelerator pump is where you really made your mark in the industry. How did you come up with the initial design concept?

Back in ’98 a lot of us thought the four-stroke would be the wave of the future, and as it turns out, it was. If you go to a supercross or an outdoor national, every bike on the line is a four-stroke. So when the YZ400F first came out, I wanted to have one just to ride, and when I first rode it, it went beyond even my expectations. But as time went on and I became more accustomed to it I noticed there was a lack of throttle response. When you revved it, it had a flat spot, and off jumps it had a flat spot, so I started messing with the carburetor. I talked to a few people to see what they thought, and even talked to some guys at Yamaha to see what they thought about the carburetor. I really learned how the circuitry of the carburetor worked and how I could modify it to improve throttle response.

After spending lots of time and money trying to modify stock parts, I went to a friend’s shop, and he and I knocked out the first generation of the accelerator pump from a piece of billet aluminum. The pump made the YZ400F immediately better, and after some tweaking, I was able to get the throttle response really good on that bike.

Over the years you’ve expanded your product line and services. What else do you guys offer?

We have suspension components that we do; our spring glide is doing really well right now. It’s a spacer that goes in between the spring and the adjustment perch that allows the spring to float freely as the suspension is going through its travel. As the swingarm compresses the spring, the glide lets it wind and un-wind so you don’t get any binding or chatter. It really smoothes out the ride.

We do internal suspension components, as well as suspension and engine modifications in-house. We also produce triple clamps for bikes all the way back to ’97. We have guys that drop their motorcycles here before they ever ride them so that we can put every afterrmarket component on it before it hits the dirt.

There are a lot of component companies out there, what do you feel makes you different?

My way of thinking is that I don’t work for the factory; I work for the general public. I try to make my components as easy as possible for the average guy to bolt and feel an immediate difference. It’s not just the pro guy who will feel a difference with our parts. A factory team changes their suspension and pulls their engine out regularly, but the guy who just rides and races on the weekends doesn’t. He just washes the bike and does basic maintenance. He can’t spend as much time working on his bike, so I make my components as maintenance free as possible.

To develop your components you work with some fast riders. Is there anyone you are sponsoring right now?

We work with Ricky Yorks, a kid that’s coming up in the Supercross Lites class. We do his suspension and I do his wrenching for him on race days. We qualified for our first Supercross in Anaheim, and we’re hoping to make our first main the weekend in San Francisco.

Do you sell your stuff internationally?

We have distributors in England, Germany, Canada, Australia, and we talking with one in Sweden. Australia does very well for us.

Sounds like there is some really cool stuff going on here at Factory R and D. Thanks for the tour, Ken.

Thank you!

To find Factory R&D’s components and for more info, check with your local dealers, or visit You can also call them at 714/338.0100.