Boyesen Super Stock, Pro Series and Power Reeds

In 1972 Eyvind Boyesen, president and founder of Boyesen Engineering, started a revolution in reed induction technology with his patented dual-stage reed. Applications for Boyesen technology have expanded from motorcycles to include intake products for watercraft, snowmobiles and outboard marine engines.

The Boyesen Super Stock Reeds, Power Reeds and Pro Series Reeds were tested out on our stock Wheelbynet.com Yamaha YZ250. The tests were performed in 58-60 degree weather at about 500ft. above sea level. Little Rock, Arkansas?? Anyway, the test riding took place under some local power lines with terran varying from relatively flat, 5th gear wide open fire road type riding to 1st gear technical rock crawling sections that would make any trails rider envious.

The first set of reeds to be put to the test were the Boyesen Super Stock carbon fiber stock replacement reeds. These are a single stage reed identical to the stock set up, except they're constructed out of carbon fiber. The carbon fiber makes them last much longer than stock reeds. Add in the fact that these reeds cost less than any OEM or after market carbon reed on the market. You can't go wrong here if you're looking to retain your bikes stock powerband.

I pulled the carburetor and reed cage off the YZ 250. It took all of about 10 minutes. I removed the stock reed stop and replaced the stock fiberglass reed with the new carbon fiber one. I put the stock reed stop back in place and repeated the steps on the other side of the reed cage. I put it all back together with out any loctite since I'll be repeating these steps at least two more times. It took about 30 minutes total.

The first ride was pretty much what I had expected. The powerband was nearly identical to stock, but a little more crisp. No jet tweaking was needed.

The second set of reeds I tested were the Boyesen Power Reeds. These are dual-stage reeds made from traditional fiberglass materials. These went on easily like the Super Stock reeds, but instead of using the stock reed stop, a rev-plate is provided. This allows more unrestricted movement of the reeds at high RPMs.

The top reed is light weight and specially shaped for partial throttle or low RPMs. The bottom reed is thicker, stiffer and ported for maximum flow and horsepower at high RPMs. The first thing I had to do after installing these reeds was lean the main jet down two sizes to a 172. I kept the stock needle and clip position. (N3EJ 2nd grove). The pilot jet is also the stock #50, but I leaned the air screw a quarter turn out for a total of 1-1/4 turns out. Stock is 1 turn out. Even before leaning it out I could tell the bike wanted to keep pulling further than the stock and Super Stock reeds. I won't bore you with the back and forth and in between settings I messed with before arriving at these settings. The biggest thing was dropping the main jet 2 sizes. Not only did it pull much harder on top, but the mid range throttle response really got crisp. Leaning the air screw out a touch gave the bottom a little more snap.

There's this very step hill, under the power lines, which is hard to build momentum before climbing because of a dry, rutted out, loose gravel creek bed at the bottom. You have to back off right when you need to be building RPMs. With the stock reeds, I'd back off the throttle until almost across the creek bed (about 20 ft.) than fan the clutch to build the RPM back up to pull third gear, in the meat of the powerband, to the top of the hill. With the Power Reeds in, there was no need to fan the clutch anymore. I could back off of the throttle, cross the creek bed, and get right back on it without missing a beat. No hesitation. It just keeps pulling to the top of the hill.

The Boyesen Pro Series reeds were the last set of reeds to be tested and they'll be the ones staying in the bike! No, not because I'm tired of taking the reed cage on and off, but these reeds are everything the dual-stage Power Reeds are and more.

First off, I kept the same jetting as the Power Reeds. When it gets hot and humid this summer, I can see going to the N3CJ needle in the 2nd position on either of the dual-stage reeds. This needle is a half clip leaner than the stock N3EJ needle. A full clip is probably too much.

The Pro Series dual-stage reeds produce even better throttle response right off idle. And like the Power Reeds, the mid is very crisp and the top just keeps pulling.

The best part of these dual-stage reeds is the additional power on demand makes it easier to go faster. Coming out of corners, you can just roll it on and confidently steer with your rear wheel knowing the power is there. Seat bouncing jumps is much better. There's no hesitation to worry about causing the front end to drop like a rock.

If I had to to sum up Boyesen reeds in one word, it would have to be CRISP! You have to see, or feel, for yourself how improved throttle response can make you a better rider. And better throttle response is what Boyesen reeds are all about!

BOYESEN ENGINEERING
8 Rhoades Rd.
Lenhartsville, PA 19534

(610) 756-6818
Tech Line: (800) 441-1177
Fax: (610) 756-4102
www.boyesen.com