no power follow-up

Tue Apr 13, 2004 12:13 pm

the 49 cub with belly mower that i brought home still has me stumped with no power. i'm unable to let the clutch out with the mower engaged with out rpms dying and tractor wanting to stall unless i push the clutch back in. here's what i've done so far -- replaced fuel line and in line filter with sediment bowl and new line--good fuel flow to carb; changed plugs- autolite 386; cleaned carb and especially main jet; looked like one wire was bad so i replacd it with one from one of my allis's, new set is on order. did a search on this site and found instructions for adjusting governor rod to carb linkage -- (btw - governor rod across the front of engine seems free and does not bind) -- according to what i read, throttle lever should be put in wide open position; rod should be disconnected; while holding the carb in wide open position (pushing rod towards back of tractor), the holes in the rods should line up -- in order to line mine up i had to adjust length about one inch -- when i did that and reassembled, throttle lever would hardly move much, engine would just surge and run out of control. had to put back closer to original postion to get to to run ok.... first - have i done that right?? 2nd....any ideas?? thanks alan :?

Tue Apr 13, 2004 3:20 pm

The good thing is that it runs - you know you have air, fuel, and spark. Just no power.

I would now check to make sure the govenor is trying to work as the engine rpm is modulated. Start the engine and see if the modulator arm moves as you speed up and slow down the engine.

If there is little or no movement, I think at this point I would remove the govenor and make sure that the weights will move and it's not siezed up. The proceedure for this is in the "Blue Ribbon" repair manual. The only hard part is reinstalling the govenor and making sure the timing marks are in-line. (Timing mark is on the back of the idler gear and back of govenor gear)

Others may have more ideas - but, I think it's heading towards the govenor.


Tue Apr 13, 2004 5:21 pm

Reading from the cub manual "with the engine stopped, advance the engine speed control lever to about half speed." disconnect governor to carburetor control rod {either end} hold carburetor throttle against its stop in the wide open position and adjust length of the governor to carburetor control rod so that it may be reconnected freely without moving the throttle lever or governor lever. next lengthen control rod one turn from the above condition and reconnect. Move the operators engine speed control lever a few times between half and low speed position to check for binding.

Just a question have you checked the timing on your cub. At high idle "wot" it should be 16 degrees before tdc.It can be set running with a timing light or static "engine off" with a test light or ohm meter.
good luck Mike

Fri Apr 16, 2004 3:06 pm

Couple things to look at:

How good is your spark? Pull a wire off one of the plugs and use a screwdriver to see how much of a jump you get. Before I replaced my plug wires I had a little weak spark that would only jump about 1/4". Now she jumps and snaps almost an inch.

Also, I was sucking a lot of air from an improper breather pipe from the oil bath filter, i.e. lots of air getting in at both ends of the connection.

Finally, what seemed to really cure my power problem was a different carb, I put the carb from the '67 Loboy onto the '49, I tell you the difference was night and day. Maybe the '49 carb is too worn out. I put a rebuild on it but that did not cure the problem. The kit was an after market and is a bit sloppy. Soon I will try ordering an IH kit and see if it's any better. These carbs can be pretty touchy. The float height has to be proper, and you must be sure you are not sucking air through a warped top half.

Whatever the case may be, you will be happy with the result. I was ready to roll mine down into the river last year until that carb swap.

Stick with it, and good luck.