reed plate -- 7 1/2 hp. evinrude circa 1957

[Meaux]

I'd like to see a discussion on reed plates for the subject little motor. How do they work? Can they be installed backwards? How does a motor act when the reed plate is malfunctioning i.e., when would I suspect a reed plate to be the problem.<br /><br />Thanks guys in advance,<br /><br />Meaux

 

[dolluper]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

Reeds time the fuel mixture into the crankcase by opening when pressure is dropped [predtermined ]on the compression stroke---tell us more about what the motor is doing or not doing

 

[Joe Reeves]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

When the piston goes up, vacuum opens the reed (leaf plate valve) allowing fuel to be drawn into the crankcase area. When the piston goes down, the pressure under the piston (along with the natural action of the reed) closes the reed, and the fuel is forced upwards and into the piston/cylinder area when the piston drops below the intake port.<br /><br />If a reed is faulty (cracked/broken), when the piston is going down, the fuel will be blown out through the carburetor throat instead of its normal route.

 

[Meaux]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

dolluper and joe reeves <br /><br /> Thanks for the quick come-back. Actually I haven't tried to run this motor yet. My step-son has had it for years and says that it will start after much trying but will only run a couple of minutes and then dies. He's had the carb apart but wasn't sure he got the reed plate back in correctly. He's in Paducah, Ky. and I'm in Baker City, Or. Again, thanks for your input --- I think I better understand the reed plates' function now. I now have the motor in Oregon and will see what I can do with it.

 

[DJ]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

Meaux,<br /><br />I have one of those engines.<br /><br />Most likely the carb is the problem. They will "sneeze" or kick back violently if they are running lean. That may be why you are suspecting reeds.<br /><br />Also, that system has the two hose pressurized tank set up. The connections must be tight and make sure there are no leaks that can cause a drop in tank pressure.

 

[Chinewalker]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

Unless the reed plate was completely disassembled, it can't go in "backwards". If the reeds themselves have been removed and then reassembled, they may have been put backin backwards, which isn't recommended, but I've seen it done. It's also possible that the reeds may have been put on the wrong side of the plate, but I don't think the manifold could have been reassembled that way. Bottom line - I don't think the reed plate is your problem.<br /><br />If your motor runs out the prime from the tank (about a minute or more at idle) and restarts when you reprime the tank (button near carry handle), then you've got an air leak somewhere, or it's not getting pressure from the crankcase. I've seen some of the rubber flappers on the reed plate deteriorate or stick, but not often. Is the gas cap tight? Tank must build pressure, so cap must be tight.<br /><br />If the motor runs for that minute, then picks up speed for a moment and dies, then think fuel delivery from tank to carb. If it simply runs like crap the whole time and dies of it's own accord for no reason, think gummed up carb.<br /><br />If it sharply picks up and drops off RPM, think ignition problem - could be cracked coils.<br /><br />- Scott

 

[dolluper]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

Here's a site that might help you alot in understanding ,search under two stroke engines www.howthingswork.com

 

[Meaux]

Re: reed plate -- 7 1/2 hp. evinrude circa 1957

Thanks Guys for the in-put.<br />Right now, I'm in a snow storm in Paducah,Ky. (White Christmas for sure). I'll check these things out if I ever make it back to Oregon. <br /><br />Meaux