I am working on a few '70's Cubs at once.... a 129, (2) 1200's, and a 1250. 2 are mine, 2 aren't.
all have sat for a while. Got spark on all, and am at the point of going thru the fuel systems.
I am noticing some different things about the carbs. All are #26 carbs. No Walbro's among the pile. I have the one from the 129 off and freshly overhauled, ready for action. I also (thought I had) another good fresh #26 ready to go/
What is the "shelf life" of the OEM Kohler needle and seat kits for these carbs? stored in the original factory sealed package.
How many variations of the #26 are there? I was gonna use the freshly cleaned and rebuilt one from the 129 onto a 1200. Got it running, adjusted out and running awesome, the carb that came from this machine was nasty green inside and stunk, I was a little afraid of how easy it might come apart /.and how well it would clean up. I went thru this carb 6-7 years ago for its owner.... but it has been sitting with old gas in it for at least 2 years recently though....
figured I'd play a game of "musical carburetors" among the tractors, as I get to each machine, I didn't even make 1 round, and got tripped up.
I have the 129's carb all clean and redone, plus 1 other #26 also all clean and (I thought) ready for service. did these over the winter and even had the bodies bushed for the throttle shaft while apart.... new throttle shafts, too.
I tried this "extra" carb on the 1200 1st, and even though it was well boiled, ( I couldn't get the main nozzle out to verify 100% clean, and didn't want to strip any threads though)
to start off with, it ran fine all the way thru the speed range but the idle mixture screw? Did not matter where it was set, as long as it wasn't all the way out in my fingers, it ran the same at idle. Even seated. Shut the engine off and gas runs out the mouth of the carb within 30 seconds if I don't shut the gas off at the tank right away. I tried 3 different brand new, OEM Kohler needle and seat kits in this carb, and 3 different floats, these a mix of OEM new and used (none seemed heavy or taking on gas) and same story.
I swapped parts, adjusted float and same story. again and again, did not even fire it up after the 2nd time, or bolt it on... hooked up gas line, hold it in place against the engine and level, turn shut-off valve on, and listen to the air gurgle its way out, and then watch the gas follow.
So, on went my #129's carb. Ran even better at idle and adjusted out better on both ends of the RPM range, too. No leakage. and I put 1 of the 3 needle and seats that I tried on the "extra" carb and one of the floats that I tried in that carb into the 129 carb and 1st try, 1st combo of parts that I tried in the extra carb, put into the 129carb/ all OEM replaceents.. No leaks, runs awesome.
Until I tried to install the air cleaner. No go/ the "extra" carb, and the 129 carb, have 3 holes at the choke end for air cleaner attachment, as the air cleaner base does. This tractor has the big oval air cleaner that has the rubber tube that goes into the shroud. the green stinky carb off the 1200, has 5 threaded holes and it uses the top and the 2 lower holes, not the ones that are straight across the center of the carb throat in line with the choke shaft. ... the 3 holes it needs to mount, are 120* apart....
at least I know the 129 carb is "tested and ready".... gonna have to clean the 1200's original carb and hope for the best because of the air cleaner mount screws....the 129 takes the regular round air cleaner base that is held on by 2 screws in line with the choke shaft.
but I cannot figure out why I cannot get the 1st carb that I tried on this engine to stop leaking... with all the new parts I put thru it, some of which went into the 129's carb and had no problems with those same parts working fine in this other carb body. I cannot see any cracks in it, the needle and seat threads are good/not stripped.... about to write that one off, at least it is/was just a spare...
and this is definitely NOT my 1st rodeo with these types of carbs, that came about 30 years ago...