tuning my 70hp

[Kevin W]

I have a 1979 70hp and i am new to outboard motors but not new to motors.<br />lets just say this: it has a rebuilt fuel pump, and the carbs were cleaned and new kit put into them, new plugs, new gas, and the compression is about 110+- cold<br />if i have a too rich of an idle mixture would the fuel build up in the crankcase at all?<br />there is no fuel leaking when it runs or if i squeeze the bulb but after it idles for a while and i shut it off it will drip a little from the center throttle shaft.<br />it has a rough idle but i just figured 2 strokes are a little rough.<br />The floats are adjusted to 11/16 like the manual i have states. and it does not overflow (i don't think)<br />the floats are not new but they look ok.<br />i did check the idle mixture but i did not want to lean it out too much (i know thats bad for 2 strokes)<br />any thoughts?

 

[DOCD9501]

Re: tuning my 70hp

When you say thottle shaft do you mean the butterfly shaft? If that is the case I am not sure but depending on the carb there is no fix besides a new one. Some carbs have bushings some arent replaceble. The butterfly shaft may be wore and you should be able to replace that. Find you S#'S AND CHECK ON WWW.MERCURYPARTSEXPRESS.COM TO SEE WHAT PARTS ARE AVALIABLE. Good Luck

 

[Kevin W]

Re: tuning my 70hp

Thats correct the butterfly shaft.<br />it does not seem loose or sloppy just a couple dozen drips after i shut it off.<br />i am also not 100% sure of the 11/16 setting being the correct number.<br />i don't have a real service manual yet.(its on the way)<br />the aftermarket ones are just too generic.

 

[DOCD9501]

Re: tuning my 70hp

With the bowl off the float should be level with the carb when you hold it right side up.

 

[Kevin W]

Re: tuning my 70hp

i am asuming you are talking about the top of the float with the carb base?<br />Quite hoestly i never even looked at the top of the float.<br />Thats why i am buying a real manual and not the generic.<br />a manual that covers from early 70 to late 80s is way too generic.<br />its good enough for basic maintenance but carb issues it stinks.

 

[DOCD9501]

Re: tuning my 70hp

When it is hanging the whole float should look to be level with the base of the carb. I know my floats have a middle line on them that you can use a a guide. Just make em level.

 

[Chris1956]

Re: tuning my 70hp

Fuel dripping from the butterfly shaft may be a carb float adjustment problem. The butterfly shafts never made a fuel-proof seal with the carb anyway, so it is not a problem. Set the floats per the manual, and adjust the idle mixture screws until the idle is reasonable, and the motor revs up smoothly in gear under load. The carbs have no accererator pump, so the idle mixture needs to be as rich as possible to allow acceleration to occur.

 

[Kevin W]

Re: tuning my 70hp

Well its running better now!<br />its amazing that the float setting was tne issue.<br />on the lower carb the float setting was set too high and the idle was adjusted to make it function that way.<br />it worked well out of the water but once i put it in the water and gave it more gas it flooded out and died.<br />Thanks for all the help guys!