Steve, you should push it to the corner of your driveway, so I can have it, then you can go out and buy a brand new mower! JUST KIDDIN'! Congrats on your mower! Is it your first LB? There are several LB fans here that wouldn't trade them or sell them off for anything, especially now since they're no longer made. It's amazing how well a 30 year old mower can still run and handle,almost like it's 3 years old! Like Walt said, those years had an aluminum tag riveted to the deck usually between the rear wheels. Later on, they used an aluminum backed sticker tags sometimes towards the right rear wheel, and some on the left side back at the rear wheel. Unless the deck had been reconditioned, those tags generally will still be visible. I'm actually getting ready to totally recondition one of mine with all new engine parts and powder coating the deck, new wheels etc. All my other LB's ran forever and well enough never for me really get the desire to do this, just something to do! This mower will no doubt be around long enough for me to end my mowing chores as an old man.

The joys of a fixed jet carburator! I would suspect that the change in barametric pressure is at work here. You said it is cooler this day that both your Duraforces have started mildly surging, Cooler air is more dense and is usually accompanied by lower barametric pressure. More dense air requires a bit richer jetting to keep the air/fuel ratio correct, also the carburators use air pressure to perform their job of distributing fuel to the incoming air stream, less pressure = less fuel. Now we are not talking about a lot less fuel, but on a Duraforce that is already on the lean edge of jetting, it wouldn't take much less fuel to throw off the ratio enough to mildly surge. I have Five Duraforces and All of them required re-jetting to get them to stop surging and I'm only at 1330 feet above sea level. If you had a larger low speed jet handy you could swap out the stock jet with one a .001" larger and I would bet that the surging would be gone. The swap would take you 2 minutes. I have a 7260A Lawn-Boy that is of 1970 vintage and the designers at Lawn-Boy thoughtfully provided it with a large thumb wheel adjuster on the main jet so the user could adjust it in about 10 seconds for daily atmospheric conditions. As you are seeing, two cycle engines are very picky about their Air/Fuel ratio. They like it a tad rich, and will reward their owners with a pleasant burbble or studdering sound at no or low loading and a wonderful power hum when loaded up. You can try fresh fuel to see if that helps the problem but most likely it is the atmospheric condtions that are causing you trouble (the key is that they both started behaving the same way at the same time), re-jetting a tad richer will stop the surging but may make it smoke more when the barametric presure rises, or you could just wait till the weather changes! Good luck!

Thank you Walt. Yes, it does have a fuel shut off and I will use that until I can get the float work done. This thing sat for 7 years with fuel in it. I took the carb apart and cleaned it out and rinsed out the tank. I used carb cleaner on the float which I learned later was a no-no. The darn thing started on the first pull and I have been using it all summer. Doing the float work will be a minor thing after all of that. I have been running a little Seafoam in the fuel to help work out any more gunk that may be in the carb. So far so good.

Hawk, Peaboby is pretty close in his explanation. One cable controls both the governor and choke (you already know this but I had to start somewhere). As the cable goes through its range from idle it increases tension on the governor spring. At about the halfway point of the cable you get full tension on the spring, that's all the throttle you get. As you push the cable further it begins to close the choke. When the cable is fully extended you are at full throttle and full choke. You will not feel the tension of the governor spring build up as it is so light. The choke has a separate return spring which is a little heavier but you really don't feel that either. In the control lever mounted on the mower handle there is a little spring loaded detent to let you know you at max throttle and any further is applying the choke. If it has worn out the cure is to replace the cable. Short of that just remove the air cleaner and make a note of when the choke starts to close as you push the lever, pull the lever back a nano-degree and your lever shows you where full throttle is. Put everything back, shove the lever forward, fire it up, idle it down for warm up, shove the lever to where you know full throttle is and go mow. Now that I've given this story you had better back it up with your own eyes as I may be thinking of the carb on an old "V" series I have. If my detent weren't detenting I wouldn't make a big deal out of replacing it. Then again, for me working on the mowers is more fun than actually using them.