J50tleod rough Idle 50 hp Johnson

[heycods]

Carbs just rebuilt, Its never the same when I start it up. runs great wot. I finaly got around to compression check. 155 top cyl 150 bottom cyl. Did someone shave the heads. am I supposed to be running 92 oct. gas. 1995 or 96 mod .love the motor great on fuel economy. It just wont do troling speed worth a flip. thanks guys for all the help. ser manuals on my motors are in the mail. lwr

 

[TxShorty]

Re: J50tleod rough Idle 50 hp Johnson

Did you build the carbs? And do you have the correct service manual?

 

[heycods]

Re: J50tleod rough Idle 50 hp Johnson

Travis boating center in Abilene rebuilt them. About the most reputible in this country.My manuals havent arrived yet.what is compression supposed to be. lwr

 

[MCM]

Re: J50tleod rough Idle 50 hp Johnson

Comp. #'s are just fine, I think the 92 octane is a bit too much though, probably ought to stick with 87-89.

 

[Mark42]

Re: J50tleod rough Idle 50 hp Johnson

If it runs well all through the rpm range but crapy at idle, then try the link & synch procedure outlined in your manual. Make sure you have a good 6" ruler to measure the linages with. My 40 twin ran crapy at idle until I link & synched it. In my case the advance rod was not set right and there was not enough timing advance at idle causing it to run poorly. This is common after a carb rebuild, because they don't always ensure the linage is set up correctly when reinstalling the carbs.

 

[Silvertip]

Re: J50tleod rough Idle 50 hp Johnson

Idle mixture setting is also critical and must be set on the water, not on muffs. Exhaust back pressure at idle changes things considerably. My 95 40HP Evinrude would plug along all day at 1.3 MPH. They aren't the smoothest engine but they are pretty tough. 92 octane is not required or recommended.

 

[heycods]

Re: J50tleod rough Idle 50 hp Johnson

thanks guys. still waiting on manuals. lwr

 

[Silvertip]

Re: J50tleod rough Idle 50 hp Johnson

You might also install a new thermostat. They tend to stick open making the engine run cold which creates an idle problem as well.