'74 Johnson 50 wont idle in water?

[melvino]

I have a newly tuned up 1974 Johnson 50hp that has had the carbs done, new power pack, new coils and new control cables. It idles great when I have muffs on it in the driveway and all is good. I put it in the water and it will not idle without giving it gas and when I try and put it in gear it just quits (because I can't have it in high idle except in neutral). Why would it idle fine with muffs on it, but not when it was in water? I am perplexed. Any advice would be greatly appreciated!

Thanks,
A new boater

 

[mikesea]

Re: '74 Johnson 50 wont idle in water?

the backpressure will take power out,you need to kick the idle up a bit,should have a large slotted screw try a turn or 2

 

[melvino]

Re: '74 Johnson 50 wont idle in water?

Thanks Mikesea! I see where there is the idle adjustment, but I had a mechanic tell me to adjust the throttle cable, is this not right?

 

[moonfish]

Re: '74 Johnson 50 wont idle in water?

I believe you're supposed to set the idle mix in real water also?

 

[tashasdaddy]

Re: '74 Johnson 50 wont idle in water?

not idle mixture!!! idle speed is what needs to be set. set the idle at 1000 rpms on muffs. then put the boat in the water, and fine tune the idle speed, so that the motor continues to run, with the motor in gear. as Mike said, muffs no back pressure on exhaust.

 

[melvino]

Re: '74 Johnson 50 wont idle in water?

Thanks tashasdaddy! I guess my question now is do I adjust the idle with the screws on the carbs or do I make an adjustment on the throttle control cable?

 

[willib0731]

Re: '74 Johnson 50 wont idle in water?

Thanks tashasdaddy! I guess my question now is do I adjust the idle with the screws on the carbs or do I make an adjustment on the throttle control cable?

Adjust on the motor for your basic settings. Only adjust your cable if the cable is way messed up. There is a balance you will need to find.