low rpm surging (not again ! )

Sun Feb 26, 2012 6:46 am

i am getting some low rpm surging. i did my motor swap, it went well. the carburator ( a cecil rebuild, it has proven flawless ) is the same one that was on the old engine, and i had zero surging with it . can it be ruled out? inspection of the gov/rockshaft showed that the throttle arm hole that the springs goes into had a slight "egg" shape. the spring is probably the original. the connection of the "sleeve" (where the bottom of the spring connects) to the rockshaft has a little braze on it to keep from slipping . there is a bit of old oil/grease in the area, and i have not lubed any of the places where the rockshaft "rides on". it is a magneto, good blue white spark, but it is the old points/condenser that came with it as a "parts tractor" motor. the motor has not been run in many,many years. the surging is not too bad,but just at low rpm, increasing speed and high end are great. anything jumps out as obvious or a head slap moment? thanks guys. coppersmythe..............................................................

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:23 am

Have you tried to adjust the bump spring in the govenor?

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:27 am

Linkage adjustment between carburetor and governor arm.

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:56 am

Eugene wrote:Linkage adjustment between carburetor and governor arm.


Yup, remove the clevis from the governor rockshaft arm, turn it 1/2 rotation at a time, testing it to just where the surging stops.

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 12:03 pm

First check the adjustment of the linkage from the governor to the carburetor:
- Engine off, control lever fully forward, carb throttle plate fully open
- Adjust linkage to the longest position that will allow the pin to just slide in without anything else moving.

If you still have surging, turn the bumper spring in just enough to stop the surging.

If turning the spring in a "reasonable" amount doesn't stop the surging, remove the bumper spring. Clean and lube it then screw it in just enough to stop the surging.

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 12:48 pm

thanks guys, i'm going to the shop later today and take my time with it. i'll let ya'll know what it turns out to be, or maybe a little of each. coppersmythe..................PS: it surged a little when it was still on the parts tractor, i guess i was hoping the gremlins would'nt follow it to the "first" cub. :roll:

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:38 pm

well guys, ya'll lead me down the shortest path. she is running smooth with plenty of response when put under a load :D :D . she has never run so good. also, the first/ reverse slider gear change was a success , no noise, very quiet. i did not change the other gears it meshes with, i guess they fit well together. thanks so much for all the advice. coppersmythe............................................a sweet little tractor ! the HA engine seems very happy down here, sorry yogie, bob, raymond :wink: :lol:PPS: it turned out to be about 3/16" of adjustment on the carb linkage, and a half turn "in" on the bumper spring.
Last edited by coppersmythe on Mon Feb 27, 2012 6:36 am, edited 4 times in total.

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:51 pm

I bet it'd be even happier up here in Colorado!! :D Yu can drop it off on your way to the slopes!!
Glad it is all ironed out and running smooth.

Re: low rpm surging (not again ! )

Sun Feb 26, 2012 9:57 pm

raymond, if i do sell it , you will be on top of the list. you can suprise bob :wink: . coppersmythe...........................................PS: i'll trade you a couple of lift tickets :{_}: