Rough Idle / slow hole shots

[blipship]

I have a 1978 Johnson 140 and it idles rough. I have also noticed that it has slower hole shots than it used to. It also vibrates more a slower speeds than it used to. Could this just be a simple problem like cleaning the carbs or could it be that I need to do a total tune-up? Thanks for any advise.

 

[DJ]

Re: Rough Idle / slow hole shots

blipship,<br /><br />Cleaning the carb's. is the major poortion of a major tune up.<br /><br />There really not much else to do, except:<br /><br />Decarb. cylinders. Use the search feature on this board and use the search word-decarb. There is plenty to read about.<br /><br />Service Lower Unit<br /><br />Change spark plugs.<br /><br />Rebuild Fuel Pump.<br /><br />I would check compression first to make sure you do not have other problems.

 

[sony2001]

Re: Rough Idle / slow hole shots

Is that a 5 cylinder running on 4?

 

[sparkroost]

Re: Rough Idle / slow hole shots

You could also have a link-synk/timing problem. You need less spark advance at lower idle. Your max advance might not be up to spec either.

 

[Mufasa]

Re: Rough Idle / slow hole shots

And it could just be a worn out motor, 25 yrs old? Start with the basics and make sure it is a solid motor before you waste a lot of time and money tring to tune what needs to be overhauled.

 

[blipship]

Re: Rough Idle / slow hole shots

Thanks for all the great suggestions. I think I will start with the basics and go from there. Probably check the compression first. Happy boating to all..