620 John
Member
I was working on a guy's model 60 and was trying to get the carb set correctly. The problem I had was telling where the idle mixture screws (duplex carb) should have been set at. I shorted out the ignition on one cylinder and screwed in the mixture screw all the way in on the cylinder that was still running. I also had the load screw turned all the way in. Somehow this thing was still running with both screws turned in and no choke on. I pulled the throttle arm back as far as I could without the engine dying and adjusted the idle mixture to get the slowest rpm. I did the same thing for the other cylinder. When I was done with the idle mixture I adjusted the load screw for good throttle acceleration. Overall the tractor doen't run too bad, it can idle fairly slow and take throttle pretty good, but still wants to spit and sputter a little at all throttle positions. Pulling the choke does NOT make it run any better. I think some of the rough running could be due to valves but I'm not sure. He also has electronic ignition installed with new coil, dist cap, wires, etc.
I know the book says to check rpm of each cylinder when adjusting the mixture but I do mine a little differently. With it running on one cylinder I just turn the idle mixture screw in until the engine about dies and back it out a quarter turn or so and do the same on the other side. This seems to work pretty good for me.
So my two question are how would it still run with the screws turned in all the way and what else could be causing it to spit and sputter??
Thanks in advance and sorry for the long post.
I know the book says to check rpm of each cylinder when adjusting the mixture but I do mine a little differently. With it running on one cylinder I just turn the idle mixture screw in until the engine about dies and back it out a quarter turn or so and do the same on the other side. This seems to work pretty good for me.
So my two question are how would it still run with the screws turned in all the way and what else could be causing it to spit and sputter??
Thanks in advance and sorry for the long post.