Well guys I learned a new one today on the fuel system of another of my Duraforce Mowers, this time it was the only pusher I own a model 10424. I had been having starting problems with it, so I installed a different CD pack but it didn't help the situation. My usual two primes and a pull method didn't work like it does on all the others and this mower has been like that since I got it. This mower will start fine when I squirt some fuel down the intake of the carb so I'm figuring that the priming system has some problem and maybe the carb because while running it surges slightly and smokes a lot for the type of oil I use. I had this problem on my daily driver (10323) first thing this spring, I thought that the jetting was too rich as I had opened up the main jet and the low speed jet one size (.001"). But it turned out to be a bad float or inlet needle and seat that was allowing a slight flooding condition while the engine was running. I stopped by my local LB dealer and got a new float and inlet valve and removed the carb to install them, and found very small particles of dirt in the float bowl. Now as many of you know I never miss recommending that folks install inline filters and shutoff valves in their Duraforces to keep dirt and grass out of the carbs, and now here I have fine dirt in MY float bowl. I'm thinking that the only place dirt can get in is thru the carb vent (also known as the primer), so I disassemble the primer bulb and there it is, lots of fine dirt. I cleaned it up, installed the new parts in the carb, reassembled the carb to the engine, installed a new primer bulb and gave it a couple of primes and it roars to life just like the other four Duraforces I have. After about five minutes of running the engine cleans out the extra oil from the over rich flooding and no more surging or smoking, the operation was a complete success. So I guess what I'm saying is the primer system needs maintainance too, maybe right before each season, more in dusty conditions. I'm thinking of cutting a small round disc of thin air filter element and putting it inside of the primer button to see if this would keep dirt out of the float bowl. Live and learn.
Fuel System Problem On Duraforce (Again)
mtgrs737
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i wonder if that one from the v could be adapted to the duraforce? think how sweet a duraforce would run then
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Except for the float/needle valve problems on two of my plastic Carbed Duraforces I have been having good luck with them. I try to not over tighten the mounting screws so I don't warp the flange. On the plus side the plastic carb won't rust or corrode like metal can and it doesn't transfer heat to the fuel and vapor lock. I think a bit of redesign on the float and inlet valve might make the plastic carbs great. (I'm giving up on an adjustable mixture screw).
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Yep, new two stroke LB's are HISTORY for us and the rest of the mowing public. We'll just have to make due with what we have. I wish I had a milling machine, I think I'd make my own carb body and you can bet it would have adjustable low and high speed mixture screws. I've had an Idea on how to make an adjustable low speed screw assembly to replace the stock fixed jet that I think would work without modification to the carb body, however it would fix only half of the problem.
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Mtgrs, sometimes a adjustable main jet can be fitted right in place of the fixed one. It might be possible to use the short low speed needle from the late '60's carb (twin needle type) and then make a threaded brass fitting with o ring seals. I never had a duraforce carburetor (or engine) and am not familiar with where the main jet is or the available clearance around the carb when it is mounted on the engine.
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Mike72, The main jet on a Duraforce in in the float bowl of the carb and has no access from the outside unless you take the bowl apart. The jet itself is a tiny brass thing with a small .031" hole in the middle and threads on the outside so it may screw into the nozzle. I think a new nozzle assembly could be made that had a long mixture needle that threaded into the nozzle from the top like the adjustable plastic carb that I have on my "F" lawn boy engine. I just don't have the proper machine tools to do this job. And now with re-jetting (opening up the main jet and the low speed jet .001" dia. larger) I'm getting the mixture close enough to make me and my engines happy.
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Finished up the Walbro LMR10 (replaced needle, seat, float pin, welch plugs and gaskets) and swapped out the plastic carb on my Toro 20442 that has a Toro 'V' (also changed throttle cables). Haven't had a chance to mow with it yet but the engine starts easily and runs well with one exception:mtgrs737 said:
I noticed in Dougmac's "Duraforce Surging..." thread that you mentioned all of your D-F's burble after you rejetted. I have 2 running 'V's (the other is a L-B) and the one I swapped carbs on doesn't burble with either the plastic or metal carb. It used to, but I don't think it has done it at all this year. However, the L-B 'V' with a plastic carb has a nice burble to it under no load. That engine is also mounted on a 20442 deck. The only difference between the 2 engines other than the PTO's is that the Toro's muffler has an outlet tube (similar to the 'F's muffler tube) instead of the L-B's louvers. Any ideas why the Toro 'V' isn't making "music"?
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From my limited understanding of two cycle mixtures I would say that non-burblers are on the lean side of air/fuel mixture, but also check for carbon buildup in the exhaust port and muffler. Two cycle engines like a slightly rich mixture. with that said, there are many factors that enter into the mixture picture, air temperature, air density, humidity, gas composition, oil type and quantity, etc. Most all these things change almost daily, when you are riding the fence on the mixture you may burble one day and not the other. The best way to ensure a strong burble is to richen the mixture up a bit more, at a cost of more fuel and possibly more smoke. On the plus side if you richen the mixture you will most likely lower the operating temp and ensure the engine is being oiled well. This is the bane of the fixed jet carb, the inability to tweak the mixture to the existing conditions. The EPA has forced us to live with lean running or possibly over rich running engines. I'll take slightly rich everytime! After all that sweet music is worth a bit more fuel! IMHO
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"Sweet music" indeed! That's what we love to hear! Thanks for the info, mtgrs737. Both engines are currently being fed a fuel/oil mix using Opti2 at 64:1 (was using Racing 2T at 32:1 and might switch back to L-B oil). The Toro's ports are clear and have never needed cleaning (bought it new in 1998). The exhaust chamber doesn't have much carbon build-up; only a thin coating. The muffler is fairly clean, too. (Does this indicate a lean condition?) After running the Toro with the Walbro for a few minutes, I backed out the idle mixture screw a few turns but the only thing that changed was increased smoke so I reset it to 3/4 turn per the manual.
I've got the LMR16 ready to go on the other 'V' as soon as I receive the cable I won on ebay. I'll let you know if it still burbles after I make that swap.
I've got the LMR16 ready to go on the other 'V' as soon as I receive the cable I won on ebay. I'll let you know if it still burbles after I make that swap.
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Why?2stroke blaise said:
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i agree its the best i have ever used but i cant find it to buy anymore anywhere. i have about 1 years worth in reserve and so i am using up my stocks of dino 2 stroke oil now
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The only reason I can think of for anyone to use L-B oil is nostalgia. They grew up mowing with a L-B and their Dad always used L-B oil so, out of nostalgia, they keep using it in their own L-Bs here in the 21st century.
In every way (lubricity, combustion thoroughness, and recommended mix ratio), today's synthetic and semi-synthetic 2-cycle oils are light years ahead of both L-B oil and all other brands of non-synthetic 2-cycle oils---it's no contest.
In every way (lubricity, combustion thoroughness, and recommended mix ratio), today's synthetic and semi-synthetic 2-cycle oils are light years ahead of both L-B oil and all other brands of non-synthetic 2-cycle oils---it's no contest.
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Dan & Tarheelman, Because Lawn Boys are fan cooled low RPM engines, I think most any of the two cycle oils will work as long as they get enough of it, I still have a problem with the ultra high mix ratios but that's another argument altogether. If you Break it down to the simplist form you have finely machined surfaces, some of which are quite soft, some pretty close clearances and lots of heat and pressure, a microscopic layer of oil is all that separates 30 years of mowing pleasure and the junk yard. The best price I can get on Lawn Boy oil is about $6 a quart and Mobil One is $7 a quart when Autozone carried it (I even got about 6 quarts for $2/quart when AZ was clearing out the old MX2T). Mobil 1 is all the things you said and more, so it's a no brainier for me I'll always go for the high tech stuff, Nostalgia buffs think about your engine and move on. :thThumbsU
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i dont like the ultra lean mixes either. i bought some amzoil sabre and mixed it at 50/1 it works as well as mobil1 and even at 50/1 there is no exaust smell at all!(i love the smell of mobil1 for some reason) both penzoil and castrol have new synth 2 stroke oils on the market now that i plan to try and i think quicksilver has some too. which is the best dino i ever used. in the meanwhile i have a huge stock of dino to use up
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Yeah, I guess you guys are right about the newer oils. I changed the oil in my truck the other day and used Mobil 1 and I care just about as much about my mowers as I do my truck! So I'll scrap the idea of returning to L-B oil. The Toro 'V' has almost no side-to-side crank end play. Same goes for vertical play. Seems to become noticeable on 'V' engines after about 10 years of use (depending on no. of hours, of course). I'll continue to use high tech oil in it and see if this helps prevent the crank play from developing. The L-B 'V' that I got used from Tarheelman last year had a pre-existing condition of vertical play. Hopefully, the high tech oil will keep it from getting worse. We'll just have to see.
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i gave up on the v engine -its a pos
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If I had the same luck that you've had with them, I'd probably say the same thing, Dan! But the fact is my Toro engine has been a fine performer for over 8 years and though it won't last the 30 or more years as some C's and D's, I don't expect it to. The L-B engine vibrated excessively because of too much crank end play but I replaced the lower bearing which eliminated that and so far it's been running well too.lawnboy dan said:
Of course, one of them may blow up this weekend! If that happens, I've got a new short block ready to fill in!
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