Reeds

Reed valves play a huge roll in a two stroke engine. The more optimized an engine becomes the less the reeds makes a difference. It is almost impossible to help a new stock two stroke motorcycle by changing reeds. Some manufacturers make the reeds thicker and stronger for reliability making perfect sense. It can be staggering how good or bad a reed can work. After testing hundreds of reeds on numerous engines the above statement becomes so obvious. Too light a reed and you lose top end and gain bottom end. Too stiff and you can lose everywhere. There is a perfect reed for your specific set up, you just have to find it. Bottom line is your engine tells you through dyno testing what it wants. It is time consuming and expensive to test reeds. If you have a given engine and test 10 sets of reeds on it you will find what reed works on that particular engine. It does not mean you have 9 bad sets. You might want to sacrifice a little power for longevity being one of those 9. There could be a few that are worthless of those 9 but one of them might work well when you move to a bigger piston or stroke. Usually most engine builders have dialed in a reed for there specific build.

Reliability comes into reed design at DBR. We run a different reed in a 3.0 liter drag engine than we do in a 3.0 liter formula one engine. We run a different reed in a 3 liter and a 3.3. I wish engines could just talk and tell you what it wants. Fortunately if you own a Mercury the reeds are in the ball park if not perfect. Unfortunately if you are building a one off science project you might be testing some reeds to find the proper set. The other conundrum is a set of reeds that could be 25 hp off optimum power can run and sound perfect and you never know. That's what dynos are for...

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