Very high speed idle after putting kits in carbs, 70HP,87, JOHNSON

[fisherman34]

I just bought a boat wiith a 87 Johnson 70HP, and it was a little hard to
start and warm up. I put a kit in the three carbs and now the idle seems
like wide open. I bought an original service manual and modified
a phillips screwdriver to adjust the low speed orofice ( this adjustment
has no effect on idle speed)
I would appreciate any suggestions .

 

[Dhadley]

Re: Very high speed idle after putting kits in carbs, 70HP,87, JOHNSON

Let's start with the adjustment. There is no low speed adjustment on a 1987 70 hp carb. What is it you adjusted with a modified phillips screwdriver?

 

[Tim Frank]

Re: Very high speed idle after putting kits in carbs, 70HP,87, JOHNSON

There is a idle SPEED adjustment on these engines but is independent of the carburetor.
Sounds like the low speed jets may have narrowed down between carb cleanings and this was offset by increasing idle speed.....to the point that it doesn't sound like the low speed jets are in play.
This is very hard on the engine and gearcase...and should be rectified ASAP.
Check your owners manual for the exact location of idles speed adjusting screw.

 

[fisherman34]

Re: Very high speed idle after putting kits in carbs, 70HP,87, JOHNSON

I adjusted the low speed orifice valve which is in the same slot as the older
needle valve assembly. Its a very small valve with a special slot, and has a hole thru the middle. I didn't see how this thing could affect the idle speed either, so I guess you verified it for me. I did see the adjustment for idle
speed on the throttle but thought this was a fine tune adjustment. That's
what I get for thinking. I will make this adjustment ASAP, and I will let you know the outcome. Thank you both for your help and sharing your knowledge

 

[Dhadley]

Re: Very high speed idle after putting kits in carbs, 70HP,87, JOHNSON

The thing you were "adjusting" is the idle jet. That needs to be seated.

The cause of the high idle is probably a simple linkage issue. All 3 butterflies have to be completely closed (not just look like they're closed). The linkages between the carbs have to be adjusted so no linkage is holding any butterfly open. The cam follwer cannot be touching the roller. The timer base has to be back all the way.