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ContinuousWave: Whaler Performance
High Proformance Power Reeds
|Author||Topic: High Proformance Power Reeds|
posted 05-31-2001 06:38 PM ET (US)
I was wondering if anyone have any experience with proformance reeds? Do they really make a big diffrence? Where are they located in a engine and what do they do?-thanks
posted 05-31-2001 07:44 PM ET (US)
Erik, the only "power reeds" that I'm familiar with are the fiberglas type.. they are used on racing engines as a protective measure so that if a reed breaks (say at 8000rpm) the engine will pass it through without damage to engine! A carbon steel reed (like our stock engines have, will break due to metal fatigue at those high racing rpm and most likely landscape the engine. I have used Boynsen (sp?) fiberglas reeds in a pro 50 Yamaha and based on that experience, would not recommend them... They wear out in one season here in Fla. and there is no noticable power increase! If you want to fiddle with reeds, just move the reed stops back abour ten thousands inch and leave the stock reeds in place.. simple job on most engines and with simple tools.. reeds are located directly behind carbs. Remove the reed plate and take it to a work bench and a couple hrs. should do it... I have done this on many, many engines and most really lit up! The Merc 2cyl 30hp can be transformed into a 40hp by moving the reed stops back or by replacing the two reed stop plates with 40hp parts.. Good luck! Clark... aka... The Old Man and the Sea
posted 05-31-2001 08:16 PM ET (US)
Ok, but i still dount no what reeds do. What are reed stops? I have rebuilt 2 carbs on a 40hp Johnson and when i took off the carbs there was nothing behind the carb, except for a hole that goes in the engine block. Where exactly is the reeds? I am asking cause im trying "beef up" 15hp mercury for a friend that has a 11' tender. Any help would be great.thanks
posted 05-31-2001 11:28 PM ET (US)
Erik, my suggestion is that you get a maintenance manual on that 15 and get some help from someone familiar with the internal workings of 2 stroke outboards. Good luck.. Clark
posted 06-01-2001 12:51 AM ET (US)
The reeds you're referring to are the leaf valves used on the two cycle engines to regulate flow of fuel -air mixture from carburetor through the intake manifold into the powerhead. I'm not familiar with the Merc engines but Evinrude uses leaf valves in a leaf plate. They are sometimes called reed valves and operate by responding to pressure or vacuum conditions from the powerhead. They consist of flexible, springy, metal leaves held at one end and mounted in a plate over an intake port. They close or open the port as required by the engine due to the pressure they feel.They are usually adjusted by means of stops which limit their travel. Similar to the behavior of a reed on a musical instrument like a clarinet.( hence the name reed valves)
On Evinrude engines when you remove the the carbs you will see an intake manifold assemble which includes a leaf plate and leaf valves.
Hope this answers your question about reeds.
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