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arkirwan

Lawnboy Duraforce motor rebuild

arkirwan
13 years ago

Hi guys,

My first post here, but have read lawnboy posts for years. I have a problem if I should rebuild my 10552 or not. I bought it from scrap last spring and ran it all summer with a rattling sound. Turns out that rattling sound was the connecting rod and bearings. In short my cylinder wall now has a single score from one of the flying needle bearings.

Short blocks from lawnboy are about $380 and to find a donor and actually overhaul it will cost about $300 it looks like. I dont want to do this again soon, so I don't want to just swap motors with a running machine. I have two other LB mowers, this is just the nicest one. . . (aluminum deck electric start). Is the duraforce worth all this time and money or will a new briggs model be less of a head ache?

What would happen if I assembled the motor with the one scratch in the cylinder?

Comments (10)

  • lbpod
    13 years ago

    It would be much cheaper to find a 'donor' mower, than
    buying a short block. BUT, rod,piston, rings, and bearings
    shouldn't be too much money. Start by taking the engine
    apart and then you can get a better feel for how deep
    the score really is. Then mike the cylinder and hone
    it out to at least remove 'most' of the score. I think
    you can take out about 0.010 of an inch and stick with
    the stock rings. Then put it together. If you've never
    done this sort of work, it will be a challange, but also
    a tremendous learning experience. To me, there is no
    greater feeling of accomplishment then hearing an engine,
    that you rebuilt with your own two hands, fire up for the
    first time. Keep in mind that this will take a lot of
    time, and if you have the time, it would be a great
    winter project. Best of luck.

  • orangedotfever
    13 years ago

    Yes, a used mower will be MUCH cheaper due to many people getting frustrated with the E series engine because of its finicky carb. They can be picked up cheap with just a simple carb cleaning needed and all the other components in good shape.

  • arkirwan
    Original Author
    13 years ago

    Thanks for the replies, I have done this sort of work, but the parts don't seem to be cheap. The crank seems ok, but the only way to get the new roller bearings is the crank assembly. I already have the engine torn down and the score is the size of the needle bearing. The piston looks like to have shared the damage with the cylinder wall. I have not miked the cylinder yet, I will do this and repost. Good to know stock rings will work .010 over!

  • walt2002
    13 years ago

    "Good to know stock rings will work .010 over!"

    That is the first time I have ever heard such a recommendation. On most engines .003" calls for oversize piston and rings though I have gone .005" but .010"??

    I don't think a cylinder damaged as you describe is salvageable though you may get it to run, I never use one.

    Walt Conner

  • orangedotfever
    13 years ago

    I agree with Walt. I highly doubt that you will be able to save that original cylinder and piston. 10 thousandth's over is a large increase.

  • arkirwan
    Original Author
    13 years ago

    Ok, so I have a chance to buy a gold series LB with the F engine electric start and 3 speed transmission for $150-$175. Would this be a better mower than the 10552? They tell me the gold series only was used to trim for 2 seasons then had the lawn done professionally. I think it will cost far more than this to rebuild the duraforce. Does anyone have an opinion which is better?

  • ewalk
    13 years ago

    Ark: .003 - .005 is what I recall as the Norm . In Racing applications even tighter tolerances .002 were required .
    Good luck with the Engine rebuild vs Replacment decision Walt and Orange have the experience to assit within this decision .

  • 1saxman
    13 years ago

    I think you will like the Gold a lot better than the 10552. It is the classic Lawn-Boy with reknowned F engine, aluminum deck and under-deck muffler. Using Lawn-Boy oil, you'll get that incredible toasted grass/2-cycle aroma as you use it, which alone is worth the price of admission. You'll most likely have to overhaul the carb before it will run if it's been sitting for years.

  • orangedotfever
    13 years ago

    I believe that you will like the F series better also. Most likely a 10515 model. Many Lawnboy users consider this the best SP model that Lawboy ever produced. In good shape, it's worth $150.

  • orangedotfever
    13 years ago

    Oops. Missed the electric start option. That would most likely be a 10545. Same mower with electric start added. At least it's not an electric start only model like some of the older ones.

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