Jonson 15 hp Workhorse

[daftdan]

Hello Fellas
I have a jonson workhorse at least thats what it says on the engine cover
I got it to run but I need help with the setting of the carb It has two knobs on the front of carb RHS slow and fast Middle lean and rich and left is the choke What is the correct mixture and what year was it made here is the engine number j2451724 if it is any help What is the funtion of these knobs and when do you use them I ran the engine on 25:1 lots of smoke It ran ok but drank fuel like it was going out of fashion so I suspect it really needs to be tuned up or are they really that heavy on juice looking forward to your help
Thanks Dan

 

[Joe Reeves]

Re: Jonson 15 hp Workhorse

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top 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. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, 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.

 

[daftdan]

Re: Jonson 15 hp Workhorse

Cheers for that info I will give it a go I will have to clean and rebuild my carb it has been sitting in a shed for the past ten years is there any thing I should be aware of other than the usual steps in cleaning of a carb any little suprises
I might encounter It was doing a lot of back fireing as it was
and hard to start a lot of pulling thanks again Dan