48 cub starts and runs but on 2 cylinders

[Detz#2]

That is interesting. What should max rpms be in a 48 cub? Where would max torque be?
How would the rpms be limited?

 

[Waif]

I was surprised at the cubs speed too. I just checked the speed with my iPhone. The cub hit 15mph in both directions. I’m wondering what modifications have been made? The gear shift had yellow paint. What farmall had a dash with 2 holes for gauges?View attachment 76163

Your throttle quadrent on the right side of the operator station doesn't suggest Farmall Cub to me.

 

[Glen]

What should max rpms be in a 48 cub?

Good that the engine runs better. Your phone may be showing the wrong speed, I don't know without being there.
1800 RPM is the maximum engine speed, from 1947 - mid 1955.
The maximum RPM is stamped in the serial number plate. If the words are faded away on the plate, or it has been painted over by someone, you probably can't read what it originally said.
Below is a picture of the style of plate used in 1948. The color of the plate is faded some.

How would the rpms be limited?

There is a maximum RPM adjusting bolt at the top of the governor.
The throttle lever has to move ahead more to increase the speed. If the lever already goes about fully ahead on the sector notches, you can't speed it up more.
I sent you a message, you get to it at the upper right of the page.

Waif, his picture looks like it was taken from the left side of the Cub, the hood is there on the left side, and it all looks like a Cub to me.

 

[Detz#2]

Thanks !
I looked at the plate on the cub and it says 1800 rpm max.
I used a tach this morning and it was 2500+ running at near full throttle.

 

[tst]

the late model cubs and stationary engines that were used on hay balers etc used governors that do 2500 rpm so maybe one was swapped out on your cub or the engine was changed out

 

[Peter S]

2500 rpm gives you about 10.4 mph