'92 johnson 40hp idle speed?

[mrolp84]

hey guys
i just got this motor and it has been rebuilt and runs great but i need to know how fast the idle speed should be cause this thing runs way to fast. it pushes my 15 foot boat at 3.5mph when idling. can anyone tell me what the rated rpms should be thanks.

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

i searched this site and found rated idle speeds of 650-750 in the water and 900-1000 on muffs. but these numbers are for older models do they still apply to my 92?

 

[kjdunne]

Re: '92 johnson 40hp idle speed?

750 in the water, in gear should be fine. I have a '89 and I think they are the same motor. You should do a link and synk per the factory manual to make sure your control cables and linkages are set up correctly. You can't set the idle correctly on muffs with no load or back pressure on the exhaust.

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

i currently don't have a manual, having trouble finding one, do you know of any links that may help me now im trying to take it out this weekend. thanks for the reply.

 

[kjdunne]

Re: '92 johnson 40hp idle speed?

You can try ebay or craigslist, but make sure it's an OMC factory manual. The Clymers and Selocs aren't worth much. Also, check here at iboats. You can definately get one at outboardbooks.com. They have originals and reprints of originals. You'll need your model #.

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

hey thanks for the reply and i did get a manual from ebay so i hope everything is right.

 

[karlow1]

Re: '92 johnson 40hp idle speed?

Nope, I have a 1990 40hp that I have been trying to fix for a few months. It still has ignition issues. It runs about 1200RPM on the muffs, and about 800-900 RPM on the lake. At the speed it pushes a 17' tin Tracker at about 2.2knts. That's a little too fast for my needs. I have not been able to get it too reliably idle at lower speeds, but it's not fixed yet.

KP

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

okay got to work on the motor this weekend and i can't get it to idle any lower than 1350. So i did some diggin on this here awesome site and cleaned to carbs for the third time then adjusted them according to a link i found on here and then i adjusted the little screw with the little lock nut. Still could not get it to idle any lower i am using a little handheld digital tach that i use to set small engine speeds with ( it's what i do for a living) and the lowest i got then was 1200 but it then jumped back up to 1350 and pretty much stayed there. now the motor sounds great and runs great. given i am running this motor in a 55 gallon drum. So i am planning a trip to the creek on wed to do a run test and maybe pick up a few more stripers. Any ideas on why i can't get the idle any lower?

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

well i did some diggin on my motor and found it to actually be a 1990 and that its a twenty inch shaft motor so with that i now know that this motor should idle somewhere around 1000rpms according to this site. so im gonna follow these here manual instructions i got and see if i cant set the idle any lower. So i will get back and tell everyone how it goes in case someone else has this problem.

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

okay just got in from working on the motor and still no luck with the idle lowering. Well i did find that while cleaning the carbs for the fourth time that the welch plug on the top of the carb had an air leak, so i put some new sealant on there and let it set up since last night. I put the carbs back on and checked all of my gaskets, reeds, and hoses. Today i started the motor after i adjusted it the way the manual states and i had the idle down around 1050 but it would not stay running and i had to back the s/s screws out to about three turns. now it will stay running but it idles around 1350-1400 and seems to get higher as the motor warms up. plus this thing smokes alot like its running really rich but its the only way it will stay running with out coughing and dying out. The cylinders are both at 120psi and jump right to that when cranked. Does anyone have any other ideas on this. Please any help is greatly appriciated. Thanks a bunch to all that have replied.

 

[kjdunne]

Re: '92 johnson 40hp idle speed?

Are the butterflies in the carb throats completely closed at idle setting? They should be. Did you do the linc and sync exactly as detailed in the manual? This is important as it syncs the timing with the carbs. When all is as it should be, the initial RPM increase when you start to add throttle is caused by the timing advancing before the carbs begin to open. Your timing may not be right for proper idle. Conversly, if the timing does not advance before the carbs open the engine will stall when you try to accelerate above idle. Of course, you aren't having that problem.

 

[mrolp84]

Re: '92 johnson 40hp idle speed?

finally i got my manual. After 2 frantic hours on wednesday the motor works great. There still is a rough idle and i still have to keep the carb screws about 2.5 turns out but there is no excessive smoke and it stays running just alittle jumpy. I followed the manual instructions for a link and synk and got it to idle somewhere around 1050rpms and it ran great in gear. I think that i Personally need to rebuild the carbs because i don't think that the seller was perfectlly honest about all the repairs. Anyway We put the boat in the water on wed evening and Success it started right up and idled great. The boat was pushed around 1-1.5 mph in gear at idle and about 25-27mph at WOT but i don't think that its reaching peak motor rpm but i am going to put a timing light on it this weekend. Thanks to everyone for all of your help. Now i have another problem I CAN'T FIND THE FISH!!! no stripers on wed but theres always sunday.