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1982 Evinrude 15 hp

DrCoxie

Contributing Member
Hello, so I'm working on this thing still and things are progressing somehwat slowly due to parts arriving from all over the place still but I've got a question in regards to the ciompression, I've measured mine at 95 psi on both cylinders and I'm wondering how that sounds. I've read a bit online but the numbers differ quite a bit. Some sites claim 60 psi is the lowest you should accept and some say around 80 is the lower side, on youtube people generally land around 100 though and yet other things I hear are that the compression is good as long as it's within 10% between each cylinder. So my question is whether 95 psi is good enough, will the engine run fine and have it's 15 hp in tact?

Little side question, are the readvalves (I have butterfly ones) supposed to let absolutely zero light through when you hold them against light or is a slight shimmer of light okey? (Engine hasn't been blowing stuff out of the carb or anything) If it isn't okey with some light, how to fix it? I've tried adjusting their position slightly which has helped some but there is still that tiny line of light.
 
The butterfly valve is in the carb is gold colored and moves with the throttle. The front one is the choke and the rear one is the throttle. The reed valves are behind the carb in the crankcase and are thin sheets of stainless steel fingers in a cage. Which ones are you talking about. FYI to access the reed valves you need to take the intake off. 95 psi is fine for your compression #s
 
The butterfly valve is in the carb is gold colored and moves with the throttle. The front one is the choke and the rear one is the throttle. The reed valves are behind the carb in the crankcase and are thin sheets of stainless steel fingers in a cage. Which ones are you talking about. FYI to access the reed valves you need to take the intake off. 95 psi is fine for your compression #s

Sorry about that, complete brain fart, I mean the reed valves and thanks a lot, good to hear! Gonna switch the crankcase seals and then it should just be a matter of figuring these reeds out to get the old dog running again. Btw, do you have any intel on which way the seals are to be installed? What I'm assuming is that the bottom crankseal is turned to keep exhaust gases out and the top seal is there to keep air-fuel mixture from leaking out right? So the top one facing inwards and the bottom one facing outwards? (sorry if thats a ****e explanation)
 
Reeds can have a small gap in them there is a spec in the factory manual. The reeds will close with crankcase pressure so a small gap is not a big deal. Do not bend them or you will have issues.
 
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