idle too high, mid-70's 50hp

pcrussell50

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looking at a used '75 50hp evinrude. owner seems and sounds like a straight shooter. says it starts and runs, but idles too high. to me, this means that it won't "idle" at all, but is actually running off the high-speed circuit of the carburetor.

i'm guessing all that would need to be done would be to rebuild the carb.

so if it's only that it won't idle, and the price is a good bit below market because of the idle, would you do it? are there other risks associated with the high idle?

i will of course, check the compression and look at the lower unit oil as well. maybe i'll even bring a stand and start it up. pretty sure he'd be willing.

-peter
 

tashasdaddy

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Re: idle too high, mid-70's 50hp

just adjust the idle speed screw. slow it down.
 

pcrussell50

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Re: idle too high, mid-70's 50hp

just adjust the idle speed screw. slow it down.

the current owner admits that he's completely non-technical, but from talking to him on the phone, he's bright and an achiever...and conscientious. a reputable repair shop told him it probably needed a carb rebuild. so he bought one, but it looked too complex for his confidence level. he will include it for whoever buys it.

so anyway, just guessing here, that if it was a situation as simple as turning a screw, i just have to bet that even the non-technical seller could have done that.

anything else besides a screw that could be causing the idle to be too high, [iow, it dies if you try to slow it down]? if so, does it point to a simple carb rebuild, or is it more likely something deal-breakingly bad?

-peter
 

5150abf

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Re: idle too high, mid-70's 50hp

On the top front of the carbs there should be a screw that controls the idle speed, I worked on my buddies 76 and was told to turn them all the way in then back out 2 1/2 turns and that should give you a good starting point.

After that go 1/8 turns and wait a second for the motor to catch up to the adjustment and be sure you turn both screws the same amount.

If that doesn't do it it could very easily be just dirty carbs and they aren't hard to clean.

On his someone got handy and adjusted them, one was 1 turn out and the other was 1/4 turn out, wonder why it wouldnt idle.
He actually brought it over cause the air box fell off, looked in the engine pan for bolts and only found 2 of the 6, the rest were resting against the reeds in the engine, sucked in as they fell out, think he got lucky on that one.
 

tashasdaddy

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Re: idle too high, mid-70's 50hp

that is the idle mixture screw, idle speed stop screw in on the side on the motor, part of the throttle linkage.
 

pcrussell50

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Re: idle too high, mid-70's 50hp

that is the idle mixture screw, idle speed stop screw in on the side on the motor, part of the throttle linkage.

Speaking of which...I was thinking of starting a new thread on this...

the idle stop screw on my big twin, 1959 super seahorse, 35hp is nylon. the head, if it ever had one is long-since, snapped off. when i grip it with pliers to try to move it or turn it, it snaps off more. so it must be frozen in there, huh? i was thinking of drilling it out and replacing it with a new nylon bolt i can get easily at the local high-end fasteners store.

seems weird to me that a nylon bolt can become frozen in an aluminum hole. then again, this is mostly a salt water motor, and maybe enough salt water sat down there for long enough? sound plausible? i've just been idling by feel, where if i pull back too far, it will stall. i'd kinda like to set it with a stop screw though.

-peter
 

tashasdaddy

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Re: idle too high, mid-70's 50hp

that nylon get brittle, why not just replace it with a short bolt, and lock nut.

on the 70's 50 the idle speed stop screw is kind of like this one, the one with the rubber tip.

carblinkage001.jpg
 

pcrussell50

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Re: idle too high, mid-70's 50hp

So, it sounds like the fact that it idles too high is not a dealbreaker then?

[assuming the compression and gearcase check out?]

remember, i was theorizing that it doesn't idle at all, but that it's fast idle is really the slowest part of the high speed circuit. if so, i can see why the marine store said it might require a carb cleaning and rebuild. but you guys seem to disagree. hmmm...

-peter
 
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