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1991 50hp no high speed

hhmarine

New member
I have been working on this motor for a while. At first it wouldnt idle so I turned up the timing stop screw and got it to idle but now at wide open it sounds like its just bogged down. Have adjusted carb settings, with no luck, I disconnected the oil injection. Is there something that tells the computer to go in limp mode if i just unhooked the wires on the oil tank? The engine has 95lbs compression on all cylinders...does that sound too low?
 
Re: 91 50hp no high speed

Oh and while running at high speed I tried spraying carb cleaner in all 3 carbs to make sure it was getting fuel and that just made the engine die.
 
Re: 91 50hp no high speed

Sounds like the carbs need to be removed and thoroughly cleaned. 95psi is a little low but as long as they're all the same it should run ok, normal would be around 120.
 
Re: 91 50hp no high speed

Could it be a crankshaft seal causing the low compression? The carbs have been cleaned about 2 months ago and it ran good for a while then it just started acting up. the gas is good adn it has seafoam in it as well.
 
Re: 91 50hp no high speed

Crankshaft seals should not have any affect on compression readings. It doesn't take much to clog up the jets, ethanol breaking down fuel lines or just old jelled fuel in the lines making it's way to the carbs. If it ran well after cleaning I would start there again, this time make sure all the lines, filter, pump, and tank are clear of debris.
 
Re: 91 50hp no high speed

I'll try it, but it just seems to me if it was a fuel problem then it would have sped up when i sprayed carb cleaner in the carbs while running it wide open. Instead it just killed it.
 
Re: 91 50hp no high speed

Crankshaft seals won't affect the compression???? a 2 cylce builds primary and secondary compression so if its loosing pressure inside the crankcase it seems to me it would loose pressure going into the cylinders.
 
Re: 91 50hp no high speed

Any 2-stroke on its' compression stroke closes off its' intake ports before the exhaust port, if you think the crankcase pressure adds to the compression reading..., trust me, it is aimed up and towards the exhaust port helping with scavenging. You can't have any compression added to the cylinder while the exhaust port is still open, compression readings start when the exhaust port is closed off. Good luck with your motor.
 
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