620 help needed

[GreenBlood]

Just bought a 1957 model 620 gas. Runs on one cyl( rt side dead) at 1/4 throttle . have new points, cond, dist cap, plugs, wires.Have fire through plug. Checked for stuck valve all work as should, adj valves at .020 while I was there. Could this be carb? Dist shaft has a little play , would this do it? at full throttle it will back fire every once in a while and try to run on both cyl

 

[GreenBlood]

Tried something else, can play with choke and will hit on two. How do you adj carb? is two barrel has two adj screws ,straight gas.

 

[Fraserb]

I had this happen to a 730 gas. My problem was a brass plug was missing on the fan shaft side of the carburator. The tractor had the same symtoms you described. Another check would be a compression test.

 

[rick deere]

One side at a time, pull one plug wire off while running adjust that side, than go to the other side and do the same letting the tractor run on one cyclider at a time, gee if you were close I might look at it for you, good luck.

 

[Dan in Ohio]

green blood,

Mike Shelby's website has some carb adjustment instructions.
Popinjohn.com

 

[Anonymous-0]

Rebuild carb-fairly easy to do but you need to be careful to avoid damage to any parts.
The idle port may be plugged-only way to get ports clean is soak for a while in good carb cleaner or have the ball plugs drilled out and then use a screw in threaded plug after cleaning idle port with a wire.
My JD 60 ran ragged from sitting to long. I kept running it using Seafoam in gas with choke pulled to where it ran pretty decent and about a year later it was running good.

 

[rick deere]

The best advice on this topic so far, I agree send it to popin john and be done with it.

 

[GreenBlood]

explain two barrel has adj screw in each barrel so the rt barrel and screw adj for rt side plug and left barrel and screw for left plug?

 

[GreenBlood]

are you adj side that plug is off or side that is running?

 

[Dave Gunem]

Not rare for these to have manifold issues also . Probably not your issue but it is a possibility . Is the throttle shaft loose in the bushings ?

 

[ET]

Pull the choke lever off the carburetor. There is a spring under that lever to close the choke but let it float to get some air in, see if that spring is broken or unhooked alowing the choke to stay on.

 

[PJH]

Adjust side that is running

 

[PJH]

That is correct. Those are the low speed adjustment screws, one for each cylinder.

 

[GreenBlood]

doesn't have spring, just tension screw

 

[GreenBlood]

that is my problem, I can pull left side side and it dies

 

[ET]

Take the tenion screw out and the arm comes off and the spring is under it.