51 B problem

pjbofmn

Member
When idling or under lite load it like fires twice then almost dies then fires twice and so on but under heavy load it fires all the time and runs good
 
Then it's probably not adjusted correctly. If you do it by the op manual, it is wrong. I can go through it with you by e-mail.
 
OK , since you are new here , here it is :First make sure your plugs are gapped right and insulator clean of ANY carbon. Set idle needle at 1 1/2 turns open , set load needle at 1 turn open. Open throttle lever so carb lever is about 1/4 open. Now start tractor and let it warm up for about 5 min. Now open throttle handle up to 3/4 - wide open throttle. Now kinda slowly shut load needle. Shouldn't notice ANY difference in tractor speed or how it runs. Now you slowly close idle needle IE 1/8 turn / wait 10 seconds / close 1/8 wait 10 sec and AS SOON as you hear ANY hesitation or miss or any change in speed,QUICKLY open needle back up 1/4 turn. In the event that it shuts down before you are able to get it open, note where it was when it shut down and open it 1/4 turn from there. Now the idle is SET,leave it alone! Now idle tractor down to real slow idle and open load needle back up 1 turn and wait 10 sec. Now throw throttle lever wide open quickly. It should quickly accelerate with about 3 puffs of dark exhaust and then run clean at wide open. It should do this without spit or pop or hesitation. If it hesitates ,open load up 1/4 turn until it doesn't. If it dark smokes more than 3 puffs then close it 1/4 turn or you can close it 1/4 turn at a time until it hesitates when you throw it open and then open back 1/4 turn. This should be good even if you are hauling a load. leave it set there unless you are plowing and it starts to run lean or pop/hesitate. Moral is : you don't set idle needle at slow idle .. NOW, if engine stops or falters when you close up load needle when setting idle , then you have an idle passage plugged or sloppy shaft bushings or both. When you say it has a "new" carb I don't know whether you mean new or rebuilt. The only "new" ones out there are aftermarket and not original Marvel Schebler . If it is a rebuilt then you could still have plugged passages or loose bushings. Some people think a "kit" and "paint" means rebuilt. Read this through and/or print it and understand it before you go out to do it. Let us know what happens. Always a chance you have governor and/or linkage problems .
 

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