johnson 25 extremly high idle

[dustyone]

I have a Johnson 25 sea horse md number 25RL75b.<br />I recieved it with carb apart in pieces. have installed a rebuild kit and it runs great, starts great however idles at about 1200 rpms. I see no idle adjust. except on throttle/shift which is backed out to free space. there is lean rich adjust on top of carb. bottom of carb has a screw (for bowl drain) however I do see a jet in that hole. Is this supposed to have a needle? points set, plugs new, fuel new, lean/ rich adjustable. and fine. float correct (and even tried lowering float level) any suggestions or help appreciated, thanx in advance, Dusty

 

[FishyBC]

Re: johnson 25 extremly high idle

Just a thought but I have a 74 25 HP Johnson and sometimes when I started it, a linkage on the side of the motor to do with the shifter was stuck and it would rev at the highest RPM until I pushed the stop button on the front. Once I adjusted it, it hasn't done it since.<br /><br />My 2cents<br />Pat

 

[dustyone]

Re: johnson 25 extremly high idle

I have gone through all linkage and none is binding all is adjusted, thanks for response.

 

[BF]

Re: johnson 25 extremly high idle

Maybe you should check the timing with a timing light. When I replaced the points on mine, I didn't get the timing (point gap) spot on... maybe you set 'em with more than spec spark advance.<br /><br />I found I could do a much better job of gapping the points by removing both plugs, attaching a timing light, and with the flywheel loose and just plopped on top, turning the flywheel by hand and watching the timing marks with the light. Remove flywheel and tweak points and repeat. I was able to get the timing just right this way. Maybe it's not your problem... but mine didn't idle right with the timing off by about 8 degrees.<br /><br />Brent

 

[dustyone]

Re: johnson 25 extremly high idle

I follow what your suggestion is, I will try in a bit. I do have timing marks however there are no numbered marks just a line on flywheel and dual lines on cover however no timing markings, so, do I just set to lines? I assume you mean set with light for optimume point break at timing mark which sounds easy enough but I dont see any btdc or atdc markings,

 

[BF]

Re: johnson 25 extremly high idle

I'm going from memory here... but in my manual I think it said to set the timing either in between the lines or on maybe on the left one (?) for re-gapping used points, and at the right mark for setting new points (to allow for some break in of the cam follower).<br /><br />Brent

 

[dustyone]

Re: johnson 25 extremly high idle

Ok. timing is set and idle is high. lol. thanks for info but my problem is still there. I dont know where else to look.

 

[BF]

Re: johnson 25 extremly high idle

Sorry that you had no luck (yet). Just out of curiousity, was the timing OK or did you have to pull the flywheel? <br /><br />Is the linkage for the timing advance and carb adjusted correctly? Again, going from memory, but I think the carb butterfly should only start to open when the roller reaches the second mark on the ramp on the armature plate. Then ensure that butterfly opens fully at WOT. Engine doesn't need to be running for this, but it does need to be in forward gear.<br /><br />Brent

 

[dustyone]

Re: johnson 25 extremly high idle

I did have to remove flywheel, a few times seting points as well as just inspecting, checking cam lobe/piston tdc etc... butterfly is completly closed ( and shows no sign of wear with inspection. butterfly is not binding nor is shaft worn. and I adjusted linkage for slack so its just carb idle still idles high. anywhere i can get a scheme on fuel system (note I can idle the motor down however riching up loads up engine with poor performqance and lean dies and will not restart seems very sensitive (1/4- 1/3 turn either way) with adjust.needle is about 1-1/8 turn out for opt perform

 

[dustyone]

Re: johnson 25 extremly high idle

I did have to remove flywheel, a few times seting points as well as just inspecting, checking cam lobe/piston tdc etc... butterfly is completly closed ( and shows no sign of wear with inspection. butterfly is not binding nor is shaft worn. and I adjusted linkage for slack so its just carb idle still idles high. anywhere i can get a scheme on fuel system (note I can idle the motor down however riching up loads up engine with poor performqance and lean dies and will not restart seems very sensitive (1/4- 1/3 turn either way) with adjust.needle is about 1-1/8 turn out for opt perform

 

[merc_500]

Re: johnson 25 extremly high idle

turn the S/S jet on the top of the carb towards the rich setting.

 

[merc_500]

Re: johnson 25 extremly high idle

sorry didnt read your last post, try turning the jet very small movements at a time towards the rich setting. <br /><br />yes they are VERY sensitive on my old seahorse if i move it just a tad it will backfire and run like crap. Once its set trust me do not move it again lol.