1973 65 HP Johnson Loss Power

J

JLMiok

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I have a 1973 65 HP Johnson. It starts and idles fine but running wide open it only runs about 10 mph where as before it ran about 45 mph. It has been sitting a while. It has 125-135 comp. on all cylinders. One mechanic told me it needs a power pack or stator. I am thinking dirty carbs. What do you all think?
 
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Daviet

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Re: 1973 65 HP Johnson Loss Power

I'm thinkin you need to do a spark test, spark should jump a 7/16" gap and be bright blue. What shape are the plugs in? If the spark checks good, try squirting some fuel mixture into the carbs and see if it runs properly. If squirting fuel into the carbs helps, it might be time to overhaul the carbs.
 
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JLMiok

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Re: 1973 65 HP Johnson Loss Power

I Forgot to say it doesn't miss just loses power.
 
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JLMiok

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Re: 1973 65 HP Johnson Loss Power

The plugs have been replaced haven't checked the spark but will do.. thanks..
 
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JLMiok

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Re: 1973 65 HP Johnson Loss Power

Well, Spark is hot and good, Spark plugs good and gapped correctly.

It starts great - idles rough and not much or a top end.

Gas in carbs didn't help much..

What you all think?
 
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Daviet

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Re: 1973 65 HP Johnson Loss Power

Compresson good, spark good, the only thing left is fuel. (gas in carbs didn't help much) If it helped at all it would indicate that the carbs need overhauled.
 
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LUKEHASTINGS427

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Re: 1973 65 HP Johnson Loss Power

I have an early sixties 40 horse johnson that is doing about the same thing. The motor starts and idles good, also seems to rev up good when in nuetral, but when in gear motor does not seem to get up to speed.
 
J

JLMiok

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Re: 1973 65 HP Johnson Loss Power

Well I have the major problems solved. I bought a M90 Neon tester and did diagnostics on my motor. Found out the Stator and Power pack was bad. It runs great now except it bogs down sometimes when I push it from idle to full throttle. I am thinking carbs for sure now. Anybody else have an idea? I can choke it a second and it will pick right up. Fuel lines and connections are good.
 
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JLMiok

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Re: 1973 65 HP Johnson Loss Power

Luke your problem definitely sounds like a carb job will fix it.
 
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JLMiok

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Re: 1973 65 HP Johnson Loss Power

I found the, I guess vacuum lines, were cracked. There is one hose from each carb connected by a Tee with no other hose connected to them. Also a hose from the crank case to the cover over the carbs. These were cracked. I repalced all of them but haven't did a test drive. Would this cause the motor to bog down when going from idle to full throttle? My biggest problem is trying to get it on the trailer.
 
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