low speed mixture on 9.5

[catfish Rick]

Hey guys this motor (which I still don't know the year, the model # is mq-10s i'm guessing somewhere in the 60's) has a knob that says low speed mixture it is located next to the shift lever, it says 1-5 and underneath 1 it has an R and underneath the 5 it has an L, what is the purpose of this, it is disconnected but the knob inside is put at 5(L), should I connect it or leave it, it does'nt idle to good and when its cold it starts on the first pull but when it warm its harder to start and when it does it sputters till it gets going, should I connect it and play with it, could that be the problem?

 

[Joe Reeves]

Re: low speed mixture on 9.5

The engine is a 1964 9.5hp Johnson. That adjustment is for the slow speed (idle) fuel/air mixture. The adjustment procedure follows.<br /><br />(Carburetor Adjustment - Single S/S Adjustable Needle Valve)<br /><br />Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.<br /><br />Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.<br /> <br />Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. <br /><br />When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.