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Run Lawn Boy with leaner oil to gas ratio??

Discussion in 'Lawn Mowing' started by fnbrowning, Apr 28, 2009.

  1. fnbrowning

    fnbrowning LawnSite Member
    Posts: 4

    Mower, 1992 Lawn-Boy S21ZSR
    To date, always used Lawn Boy oil @ 32:1

    First, the back story:

    The lower seal started leaking again, and oil was sprayed across the deck. 3rd seal in the last 5 years.
    1st time I just replaced the seal. 2nd time I checked the crankshaft (even though I never hit anything hard) replaced upper & lower bearings, + the seal. This time, I asked the repair counterman at the lawn, garden & feed supply store what gives?

    He asked if the muffler was heavy with carbon. It was. The repair counterman said that the mufflers could get clogged and cause back pressure. Suggest I de-carbonize or replace the muffler & seal.

    GET THIS! He also claims that the 32:1 mix is too rich. That Lawn-Boy was being far too conservative on their lubrication standard. He sez that you can run a modern 2-cycle oil in the Lawn-Boys at 40:1 and still provide sufficient lubrication, while keeping the carbon buildup down.


    What say you all? My 2-cycle trimmer, blower and chain saw all call out 40:1 With the new lubricants - may of which are synthetic, - can the ratio be pushed up for this 1992 Lawn Boy as well?

  2. Ben's Landscape

    Ben's Landscape LawnSite Bronze Member
    Posts: 1,438

    I have herd that also that the 32:1 was to heavy for the mowers. Right now i am having a carb issue with mine and oil is pouring out the exhaust. I would suggest slowly leaning out the oil. Say 36:1 try that then got to 40:1 if that don't work. Good luck.
  3. fnbrowning

    fnbrowning LawnSite Member
    Posts: 4

    Thanks Ben.

    Anyone else what to chime in before I buy gas for the new season?
  4. Oh Lord, please try some Amsoil Saber at 80:1 and save yourselves some money and fumigation.
  5. Are you buying gas for the entire season and mixing the oil just once this season? I know you are new to the forums so I would advise for you to look at some of the 2 stroke oil threads we have had on here in the past year. People are coming around to using Amsoil Saber which is 100% synthetic oil and it is recommended by Amsoil for it to be mixed at 100:1.

    One fellow on here has been giving away Amsoil Saber samples.
    Is the info link to the oil. Welcome to Lawnsite.
  6. blake101

    blake101 LawnSite Senior Member
    Posts: 563

    While we are talking about it, how do you de-carbonize it?

    He asked if the muffler was heavy with carbon. It was. The repair counterman said that the mufflers could get clogged and cause back pressure. Suggest I de-carbonize or replace the muffler & seal.
  7. I assume it would mean removing the muffler and soaking it in a solvent of some sort. Then the carbon might soften up and could be brushed away with a wire brush.
  8. Roger

    Roger LawnSite Fanatic
    Posts: 5,923

    Pennington, the reclaiming of a muffler might be more difficult than it seems. I have a LB DuraForce that I used for several seasons. It was a great source of trouble for me (three short blocks in four seasons). After one of the short block replacements, I decided to try using a richer fuel mix. I think I tried 40:1, and ran for about four weeks before the muffler was clogged. I saw no way to even start to get it cleared out. Actually, I have two clogged ones in the corner of the shop. I kept them thinking I could borrow a Sawz-All to cut through it to see what was inside -- never did that, however.

    I am doubting that much of anything would dissolve. There is no clear passage way to get anything inside to clean, scrape, or scrub.

    Clearly, the hazard of trying to be "on the safe side" with a richer fuel mixture will come back to bite. The buildup in the exhaust ports and muffler make this "good deed" downright disastrous.

    I formerly used a LB, model F (just before the DuraForce engine). This engine was notorious for exhaust port clogging with LB oil, 32:1 (as recommended). I needed to take off the canister muffler on the bottom to get access to the ports for cleaning. I still have a 3/8" wooden dowel in my toolbox - always with me, never knew when I would need to do a cleaning task. I switched to a synthetic oil at 75:1, and the clogging problem was gone. The engine has huge service hours, and always has run very well. The DuraForce, ... well, that's another story for another day.
  9. fnbrowning

    fnbrowning LawnSite Member
    Posts: 4

    Like Rodger said. de-carbonizing a LB muffler is harder than it would seem.
    The only suggestion I got was to remove it, fill it with gas and burn the carbon out! :eek:

    I told the repair counterman that I considered that idea too dangerous! :nono:

    On another note, sorry guys, I'm not going to drink the Amsoil Kool-Aid! :laugh:

    But it looks like 40:1 is reasonable for new formulation oils.

  10. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    If you don't like Amsoil, use Opti-2. I can tell you, the 32:1 is just for LB oil, not any "modern" oils. You are lucky to even find lawnboy oil anymore.

    I also don't understand why people are quoting the Amsoil Sabre as being an 80:1 mix, it's not. It's supposed to be mixed at 100:1, and it works just fine at just that. I've been mixing Opti-2 at 100:1 for YEARS and have trimmers that run as good as new that are 4+ years old and get used like crazy every day.

    The Opti-2 (and the Amsoil Sabre) are both a "all for one" kind of mix. The mix ratio of the oil to gas is irrevalant to what you are putting it in. They will work is any 2 cycle engine. Now some OLD equipment, and I'm talking OLD, may spec 16:1, and I'd be leary of trusting a 100:1 mix in something like that if you are really worried about it.

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