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Good eye Mike. The photos were taken right after final assembly and the governor has since been adjusted properly amongst other things. The mower doesn't smoke unbearably but just a lot more than my F and D-400. I have spent quite a bit of time trying to dial it in with the mixture screw but it seems to have little or no effect. As a matter of fact the mower runs its best with the screw turned 1/4 out from the seat. The fuel consumption seems to be higher on this mower and I know that's why it probably tends to smoke more. What would cause that? Over all the mower runs great but just sucks gas and smokes more. Maybe the carburetor body is shot??First off,I can barely see it in the picture (so I may be wrong) but it looks like the throttle arm/governor rod is in a straight up position. If it is, your governor needs to be adjusted. At rest the lever should be at a 45 degree angle. Although this is not making the smoke, it should be right before checking the high rpm (3200) and adjusting the carburetor needle.
Mike I know exactly what you are explaining here. When I went through the carb I decided to order all brand new parts for it. When I went to assemble it I did notice that the new main jet was indeed longer with no hole in the side as you describe. I thought it might be the incorrect jet since it hung lower into the float bowl so I didn't use it and decided to use the old one that originally came out of the carb since it was clean and un-damaged. Do you think that Lawn Boy redesigned the jet to correct the symptoms that I am experiencing? Maybe the absence of the side hole in the newer jet leaned the mixture just enough to cure the problem??? Let me know what you think.I just remembered something about this carburetor. There was a new main jet that superceded the old one. The part number for both is the same,(607568) but the newer one is longer and does not have the side hole. The length of the new jet overall is 1.536. The old one is .825 long overall. Of course you may already have the newer one.
No I haven't seen the bulletin. Post it up so we can all see it. I do have the newer style jet so it won't hurt to try it and see what happens. Thanks for researching.Ross, have you read the service bulletin on the jet change? I can scan and post it later today. It mentions hot start problems as the reason for the "fuel nozzle" change, but says nothing about fuel consumption, but I wonder. Interestingly the bulletin is dated 1972 and your mower was made in 1974.
The muffler is clean. I thoroughly cleaned it when I rebuilt the mower. When the mower gets good n hot the smoke subsides some but puffs out more than I think it should. Thanks for the compliments.Assuming the carb mixture is correct, where the engine should be "four cycling" only a small percentage of the time, the muffler could be loaded with deposits that take time to burn out. Try to run it under a good load for a while, if this is the problem, the smoke will increase and its smell will change, then it should diminish. That is, by the way, a very nice looking mower you have there.
