1996 25 HP Johnson

[carinya]

Hi,<br />have just purchased a 25 hp Johnson 2 stroke and found that up to about 1/3 full throttle, it runs fairly roughly - possibly on one cylinder. Beyond that she goes great. Its just been serviced, plugs are new and Ive been told compression is good. Any ideas?<br /><br />Thanks

 

[marinemech]

Re: 1996 25 HP Johnson

2 or 3 cylinder? if 3 remove oil mixer run 50:1<br />make sure sync and link ok<br />check plugs should be champion<br />make sure good oil<br />check running temp

 

[carinya]

Re: 1996 25 HP Johnson

Thanks...its a two cylinder. Oil, fuel and plugs should be OK - as specified. Excuse my ignorance but what is sync and link?

 

[G DANE]

Re: 1996 25 HP Johnson

Carinya it sounds like all it needs is adjusting the iddle mixture. It is done by the little brass screw, visible at the front of airsilencer on carbureator. Do following: motor should be on boat, boat in water. Run the motor at WOT - full speed for a couple of minutes. Go down to iddle speed, motor still in forward gear, boat moving along in water freely. Stop motor. Turn the mixture screw all the way in till it GENTLY seats. Force here can damage seat or needle. Back out 1 3/4 turn. Start motor, put in forward gear and let it pull boat, iddling. Start turning screw in, 1/8 turn at a time, letting motor respond to each new setting. When it starts to miss or "Sneeze" back screw out 1/8 turn again. Best setting is within 1/8 turn out/in from there.

 

[G DANE]

Re: 1996 25 HP Johnson

The Sync on that motor is simple. On front of stator plate, just below flywheel, there is a cam that activates throttle. The linckage should be set so the opening og throttle on carbs begin exactly when the roller is in center of the two marks on the plastic cam.

 

[carinya]

Re: 1996 25 HP Johnson

Thanks very much for the responses. I'll try your suggestions this weekend when I'm on the water.