1972 9.5 Johnson bogging at full throtle

[cottagebound]

I recently purchased a 1972 9.5 johnson motor. The motor has no problem starting but after you increase the throtle and keep it at that speed the enging seems to bog down and then seems to speed up again and then sometimes die. It start back up no problem but cannot seem to stay running at anything more then half throtle. Runs fine if you keep it slow. When I bought the motor they told me they had just put 2 new coils in it. Any suggestions.

 

[tashasdaddy]

Re: 1972 9.5 Johnson bogging at full throtle

dirty carb. air leak in fuel line. weak fuel pump. vent not open on fuel tank.

 

[cottagebound]

Re: 1972 9.5 Johnson bogging at full throtle

The vent is open on the tank all the way. I tried when the engine was boggin to squeeze the prime pulb ot see if it would make a difference but no change. Will have to take a look at the carbs

 

[Rick.]

Re: 1972 9.5 Johnson bogging at full throtle

Sure sounds like the high speed jet needs cleaning. It is in the bottom of the carb. where all the crap would try to settle. If you haven't done so you should get a rebuilt kit to put in while your cleaning it anyway. The new kit has a clip that attaches the needle to the float which is a much better setup IMO. Best of luck. Rick.

 

[cottagebound]

Re: 1972 9.5 Johnson bogging at full throtle

Just got kit and took carb apart and it only has low speed needle and float in it no high speed. Carb does not look that dirty but will see what happens after I put it back together.

 

[Rick.]

Re: 1972 9.5 Johnson bogging at full throtle

It hasn't a high speed needle but it does have a high speed jet. Have a look here. It is in the bottom of the carb. inline with the drain plug (behind the drain plug). Looks are deceiving, the little ports and pathways may well be dirty no matter how clean the bowl looks. Best of luck. Rick.

http://shop2.evinrude.com/ext/index.aspx?s1=e2fd4dc2a753f65237fd68af1523ff14

 

[cottagebound]

Re: 1972 9.5 Johnson bogging at full throtle

Cleaned carb and used carb kit and now engine runs at full throttle well.

Thanks for all the comments

 

[Rick.]

Re: 1972 9.5 Johnson bogging at full throtle

It's always nice to end with success. Well done. I hope you get lots of enjoyment from your engine. Rick.

 

[cottagebound]

Re: 1972 9.5 Johnson bogging at full throtle

I have 2 other questions

Spark plugs I have J6C in them know Manual says J4C. I have read people saying they are using J8C. Which is the best plug to use.


Also when you are adjusting the slow speed setting on the front of the motor. How many times should you be able to turn it. I am trying to adjust the idle on it but cannot seem to get it correct.

 

[Rick.]

Re: 1972 9.5 Johnson bogging at full throtle

The slow speed needle isn't for adjusting idle speed per say. It is for adjusting you air fuel mix at idle speed. To adjust idle speed, there is a knob right on the starboard side of the tiller knuckle. If you turn it counter clockwise and then turn your tiller clockwise you should see a drop in RPM at idle. It is a great cruise control for adjusting trolling speed as well. I don't remember the right plugs but I'm sure I don't use J8C's so probably J6C is the correct one but don't take that to the bank. I will have a look later tonight. Rick.

 

[cottagebound]

Re: 1972 9.5 Johnson bogging at full throtle

Rick did you have a chance to take a look at which plugs you are using

 

[ezeke]

Re: 1972 9.5 Johnson bogging at full throtle

The recommended plug is part number 0378101 the Champion J4C, which supersedes the original factory plug, the J4J.

You can find the current recommendations on the cylinder and crankase parts lists for your motor at the BRP parts catalog site. http://shop.evinrude.com/