'72 Sears 4hp smoking bad!

[chris2112]

I have a '72 4hp Sears motor. I have checked the compression, cleaned the carb and the plug. The manual calls for 16:1 mix and I have that in. I can get it to run and idle pretty smooth but, it smokes quite a bit, to the point that it will make you sick when trying to troll with the motor. I have the fast jet set at about 1 1/2 turns out and the idle mix at lean best. Any body have ideas or, are these just smokey motors?

 

[popsmazz1]

Re: '72 Sears 4hp smoking bad!

try 24:1 with modern oil.

 

[twocyclemania]

Re: '72 Sears 4hp smoking bad!

I don't know if you have an air cooled or water cooled but it seems to me that the air cooled put out more smoke. Just might be that some of the smoke gets mixed with the exhaust / cooling water on the water cooled motors. It might just be my imagination but anyway when you're running a high concentration of oil like 16 to 1 you're going to have a bit of smoke. If it's running well leave it alone. (troll faster - leave the smoke behind).

 

[F_R]

Re: '72 Sears 4hp smoking bad!

High speed jet at 1 1/2 turns out??? Isn't that a bit much? Does it run ok at full throttle? At wide open throttle on a boat, on the lake, turn the needle toward lean till it starts to falter, then back it out till it regains power. Same with the slow speed needle, setting it at idle speed.

It is supposed to smoke.

 

[RogersJetboat454]

Re: '72 Sears 4hp smoking bad!

Is this liquid cooled, or air cooled?
That being said, are you using the right oil for the motor (TCW-3 for liquid, or air cooled oil for... uhh air cooled)?
Is this a factory manual you're looking at? 16:1 just seems awful fat for a "modern" '72 engine.