Reed Q&A

Reeds are intake valves for your high performance two-stroke engine. Installing a new set of reeds is one of the least expensive methods of improving the performance, and installation is fairly easy. Here are some of the more commonly asked questions about reeds, with common sense answers.

What is the life expectancy of stock reeds?
Stock OEM reeds typically last anywhere from 3000 to 10,000 miles of riding. Sleds used for extended high RPM riding will see the reeds lasting a shorter period, while easy going low rpm riding will see much extended life times. Generally, mountain sleds are where the reeds don’t last as long, with high-speed lake racers being another case where the wide open throttle application takes its toll.

Generally, reeds last longer in Yamaha models than any other brand. We believe this to be due to the Yamaha cage design, a derivative of the TZ250 race engines, and their use of only the highest quality reed materials from Japan.

While most riders will not perform a specific check on their reeds on a preventative basis, anytime you’re performing top end service (pistons, rings, cylinders) or have the airbox off to jet carbs and the sled has 3000-4000 or more miles on it, it would be a good idea to inspect the reeds since you’re already in there. Of course, if you suffer any kind of performance issues with running quality (or if the sled doesn’t run properly after backfiring) the reeds should be checked. In reality, they are quite fragile “intake valves” on your two-stroke engine.

To maximize airflow, replace the stock intake valves with Boyesen RAD Valves.

What is the life expectancy of aftermarket performance reeds?
The recommended replacement time for aftermarket performance reeds is typically around 2000-3000 miles, with a seasonal inspection. Aftermarket reeds generally will not last as long as stock reeds due to their lighter construction and more responsive performance characteristics. You will typically trade-off some longevity for performance gains.

How can I tell if my reeds need replacing?
Most common is to find chipping or cracking of the tips and ends of the reed petals. Any visible damage is basically unacceptable. You’ll also want to check to see if the reed is sealing against the reed block. Hold the cage up to a light and look at the seal along the reed edge and the cage. If you can see the light, then get out the feeler gauge – just because they don’t seal perfectly in a static mode doesn’t mean they’re faulty in the engine. If the reed ends sit more than 20 thousandths off the reed block sealing surface, then they should be replaced. Closely inspect the rubber-sealing surface of the cage, especially on Ski-Doo models, as this has been a problem. Also clean any belt dust you find, it’ll surprise you the amount of crap that’ll ends up in the cages with no effective filtration system on sled airboxes!

VForce 3 reed cages deliver strong mid-range response along with improved top-end performance.

Is any jetting required when installing aftermarket reeds?
Generally, no, but we all know most every sled on the planet will benefit from some tweaking to the jetting. In our experience with the Boyesen RAD valves we’ve seen where you have to drop the mains one size. This does not actually lean the jetting; rather, the RAD valves flow so much more air AND fuel that you have to drop the mains one size just to get back to the original fuel-air ratio, or you’ll end up too rich! It’s not uncommon for sleds to run better with tweaking of the air screws, regardless of what kind of reeds are in there. For the most part, start with the stock jetting and make changes as needed, but this is more the exception than the rule.

Will aftermarket reeds work in EFI's?
Yes, EFI's usually respond well to aftermarket replacement reeds (petals) with no other changes. As for replacement of the entire reed cage, this can be a different story because complete cages usually change the airflow characteristics so much more than a set of petals that this becomes a case-by-case basis. Here, it is best to buy your reeds from a speed shop that has experience with the specific model in question as to whether the cage is compatible with the EFI of that particular model. Basically, if you have an EFI you’re safe installing petals on the stock cages. Installation of complete cages should be verified as being compatable with a reputable shop.

Will aftermarket reeds work in sleds equipped with altitude compensators?
Yes, both cages and replacement reeds can be installed into sleds with compensators. Altitude compensators have no effect on the reeds. The compensator is providing a percentage change in fuel flow, and the carbs can still be tuned for specific modifications or combinations of mods. For stock sleds with compensators, replacement petals usually drop right in with little if any changes, while cages may require a slight bit more tuning due to their drastic changes in airflow characteristics.

Will aftermarket reeds affect clutching?
Generally not by themselves. Now if you were to gut the airbox along with the installation of a set of cages then the engine’s power curve is changing enough that you’ll see even more benefits with clutching changes. While the installation of reeds do not require clutching modifications, remember that most every sled on the planet, regardless of reed configuration, can be improved upon with clutching changes.

Boyesen's dual stage Power Reeds replace the stock reeds on your OEM cage.

What benefits can I expect with aftermarket reeds?
The engine will become more responsive throughout the entire power curve, with the biggest gains in the midrange. This is where the reeds are working their hardest, through the mid range. When replaced by themselves, reeds will generally provide a much quicker rate of acceleration. Your sled will pull through the mid-rpms faster, accelerating harder. You’ll also notice differences in the partial throttle settings. In some cases you will see a 2-4 hp gain at peak rpm, but as the engine cylinder size increases the gains are generally bigger. Also, the gains are magnified when done in conjunction with other airflow enhancing mods. Reeds by themselves are usually not the single biggest airflow restrictor. These days, the intake (airbox) is the airflow culprit, even more so than exhaust systems in some cases.

Should I replace the reed blocks or just the reed petals?
Is the sled otherwise stock, or are there other mods? If you’re looking for an inexpensive way to maintain the sled and get added performance from a stocker you can replace just the reed petals. If you’ve done other mods (airbox, cylinders or exhaust) or value performance more than price then you’ll appreciate replacing the entire reed block.

What reed material is better, fiberglass resin or carbon fiber?
For all-out performance carbon fiber responds quicker to different engine pressures, but is a more brittle material and (usually) fails sooner than fiberglass resin. Carbon fiber is lighter and responds quicker, thus performs better, but history has shown us the ends appear to experience damage sooner. For reliability, fiberglass resin has proven to outlast carbon fiber in durability tests.

Carbon Fiber replacement reeds, like these from Carbon Tech, respond quicker than stock reeds and improve throttle response.

What sleds seem to respond best to the addition of reeds or reed cages?
Generally the larger engines see more of gain than do smaller ones. While Arctic Cats seem to usually respond the best as a brand, Yamaha engines seem to leave less performance on the table than do the rest when it comes to the reeds. The big-bore 800 and 900 twins from Arctic Cat (carbed versions) REALLY respond to the addition of reed cages, especially when you also gut the airbox to increase the airflow. The big block twins from Polaris are another good example that respond well to the addition of reed cages and see gains with the removal of airflow restrictions in the airbox. Remember that anytime the airbox configuration is changed there will be jetting changes required to provide the proper amount of fuel to match the increased airflow. In some cases, the stock jetting that was safe down to –20 can be left intact, but will now only be safe to a warmer temperature. For these reasons you should check with a local performance shop for combinations that really rock for your riding area, they’ve done a lot of the ground work so you don’t have to.

On the new 800 twins from Ski-Doo, we’ve seen good results (bang for the buck) using aftermarket reed petals on the stock cages. On Yamaha 700 triples, replacement reeds work well with single pipe set-ups while cages become worthy when triple pipes are added. On many of the smaller cc engines the difference is much less – we wouldn’t mess with it on a stock 500 or 600 twin, but would do it to every (carbed) big block engine.