There's no greater feeling than to jump on your 2-stroke, pin the throttle and have your butt about slide off the back of the seat, right? Too bad it doesn't always happen that way.

If the rear tires aren't able to hook up, chances are that tap on the throttle just resulted in a big roost…. and though you might have looked cool, watching your buddy pull away probably wasn't what you were looking to accomplish. So how did your buddy just hook up and pull away? Well, he may already have known what I just discovered - The advantage of a powervalve!

I must admit, I had heard a lot of hype in the past about them, and then just dismissed it as just that…hype. But after a recent trip to California's Dumont Dunes and sighting several powervalves in action, I decided it was time to step things up a bit and check things out for myself. I contacted ESR.

Eddie Sanders Racing has been developing products for the 2-stroke for nearly 20 years. That means some of the most innovative and successful designs in the industry. They offer products and services to many different types of racers all over the world. Every product they sell is thoroughly tested on their in-shop dynometer, and then put through rigorous testing at the track to ensure performance and longevity.
ESR races everything they sell, so not only do the products have to look good, they have to work too! ESR uses state-of-the-art CNC machine tools to produce their parts at their own facility assuring product quality and availability. They strive to be a "one stop shop" for all your racing engine needs. You'll not only benefit from race winning heritage, but also receive expert technical advice and some of the best customer service I've encountered in the industry.

I spoke to Robert at ESR and told him exactly what I was looking for out of my quad. After some much-needed technical advice, I decided to go with a 350PV. To keep things relatively on the reliable side I chose not to stroke the crank, but instead to simply have them rebuild it and install a Long Rod. I would also have to send them my center cases to be machined to accept that much larger piston skirt of the 350.

The powervalve kit itself comes complete with a Power Valve cylinder fully custom-ported to your particular riding style. The TRX9 all around porting which I chose, is for mid- to top-end power. They also offer TRX7 MX/Woods porting which is a low-end option TRX11 that is all out high-revving power.

The kit also comes with CNC Machined Billet Aluminum Powervalve assembly and two-piece head kit with two domes. To complete the kit a new piston, billet water neck, gaskets and all necessary hardware are included. Total price $1,599.

After ordering the kit, it took a short but anxiously waited 6 days for the motor, cases and crank to return. I then spent the next two evenings (about three hours) assembling and installing the 350PV motor into my 86R. After completing the installation, I installed a new K&N Air filter and Pre-filter, filled the radiator and Gear Case with Maxima Fluids and installed an NGK BR8EVspark plug. It was time to bring my new power plant to life!!!

It took only two kicks and the motor woke up! The next day would be a day for breaking it in and making any final clutch and carb adjustments. After a couple of days sitting dormant in the shop, there finally came another day off from work to get this thing out and see what she was made of.

The first noticeable difference other then the tremendous increase in power was how smooth everything had become. The "BIG HIT", which has become a signature of most 2-strokes, had seemingly become a much broader and smoother power band. Though there's something about arm ripping 2-stroke power I've come to love, the reality is, the Powervalve has made my quad considerably more manageable and easier to ride. With almost 4-stroke-like power, it has resulted in a lot less rider fatigue and a whole lot more traction in all types of terrain. Check back later for an update on its long-term reliability and how well it stacks up against the competition.

HOW DOES IT WORK?

The Powervalve works by a side at the exhaust side of the cylinder that remains partially closed usually below 5000 RPM. Then as the throttle is increased and the RPM's raise more exhaust pressure is built up, which then escapes through a small hole in the cylinder located at the power valve assembly. This causes the slide to gradually rise, raising your port timing for better top end power. Which gives you the best of both worlds with great low-end power and an unsacrificed top end .

Eddie Sanders Racing
1510 Main St Unit "C"
Visalia, Ca 93292
(559) 625-3157
Mon-Thur 9am-5pm, Fri 9am-3:30pm PST
WWW.ESR250.com