Shop Products
Houzz Logo Print
baymee

Lawnboy lemon in the shop

baymee
12 years ago

A man asked me to look at his Lawnboy, the last year of the 2-stroke Duraforce 6.5HP.

The symptoms are that it starts easily and sometimes revs up high and quits, sometimes putts along at idle and dies, sometimes cuts grass and dies, sometimes doesn't respond at all to the throttle, and other things.

It's been to a reputable Toro dealer in the area several times and about $500 later, it's still a lemon. It might work at their shop, but the fix only lasts from minutes to maybe a week.

It has had 3 new carburetor replacements, a coil, a crank seal change, tested for air leaks and who knows what else.

The fuel is always fresh, not contaminated.

When I got it home, I primed it twice, put the choke on and it started right up, only to die in two seconds. It wouldn't restart. I tried a small shot of carb cleaner and it started right up and died.

It seems like a carb or fuel issue, but 3 replacement carbs later blows the varnish theory.

Maybe you guys can put your thinking caps on and I'll take a closer look at this in a day or two.

Comments (15)

  • rosemallow
    12 years ago

    I haven't worked on a 2 stroke for years, but did you change the reeds or reed plate?
    Is the muffler clean inside?
    I remember when we would take the round ports and make them square to get more horsepower.

  • 1saxman
    12 years ago

    Ports/muffler clogged
    Reed valve/bed bad
    Crankcase seals out of position or leaking
    Crankcase leaking pressure/vacuum from a botched reassembly/wrong sealant

    Remove the exhaust transfer pipe cover, pull the 'U' pipe out and look at the ports. If the mower has been operated extensively with the choke on, as is common with uninformed users, it could be severely carboned-up. Look for excessive residue oil at the crank seals - they tend to blow out, and usually can be re-seated. You may be able to stake them in - consult an 'E' engine shop manual.

  • baymee
    Original Author
    12 years ago

    The last time I saw a reed valve was in 1974 when the Japanese motorcycles were overtaking the sales of the Triumphs and Harleys. I was a Triumph mechanic and never messed with the Yamahas.

    Aren't they behind the carb and how would I check them other than compression testing?

  • baymee
    Original Author
    12 years ago

    The reed valves seem very good and seated. The compression jumps quickly to 125 psi. The top of the piston has "some" carbon on it. The crossover pipe and muffler are not clogged, but raw gas came out when I removed the cover. The fuel tank was empty so it's from the past.

    The carb is spotless and all linkage is good.

    Before I remount the carb, is there anything I should check with the reed valves?

  • baymee
    Original Author
    12 years ago

    The reed valves seem very good and seated. The compression jumps quickly to 125 psi. The top of the piston has "some" carbon on it. The crossover pipe and muffler are not clogged, but raw gas came out when I removed the cover. The fuel tank was empty so it's from the past.

    The carb is spotless and all linkage is good.

    Before I remount the carb, is there anything I should check with the reed valves?

  • ewalk
    12 years ago

    Bay: Yes the reeds are attached to the intake port inboard of the carb. I usually check the leading edges of the reed using a flash light from behind the reed block assembly. Also prior to removal and checking with the backlight , listen very closely (perhaps using a small section of fuel line as a stethescope for only one steady draw of air per engine revolution. any secondary or intermittent air leakage would indicate a wornout reed . Usually a worn or broken reed will cause backfire back through the carb at idle or during acceleration.

  • baymee
    Original Author
    12 years ago

    I went over everything: flywheel key, carb, governor, hoses, fuel,coil gap, reed valves, choke action and found nothing.

    Put fuel in it and it started right up and ran for a few minutes flawlessly. It's dark outside, so I'll wait till tomorrow and let it run a tank through cutting grass.

  • andrelaplume2
    12 years ago

    sound like a real challenge and you have my sympathy however you said you knew of a good toro dealer in LV pa...can you reccomend them...are they near the Valley...can you name them...

  • baymee
    Original Author
    12 years ago

    Try V&C Accessories or Albright's Hardware

  • rosemallow
    12 years ago

    BTW Baymee, I was a BSA and Yamaha mechanic.

  • orangedotfever
    12 years ago

    E series engines can be quite temperamental. Mostly carb problems with those. By the way, a compression test at the cylinder will tell you nothing about the condition of the reeds.

  • baymee
    Original Author
    12 years ago

    BSA mechanic at Blackman or Links?

  • baymee
    Original Author
    12 years ago

    I definitely know it's being caused by the governor vane, or the spring, or something associated with it.

    With the carb off, the vane turns freely. When the carb is attached to the block it is binding. The bolts aren't overtightened to my knowledge. What is the inch pound torque on them?

  • baymee
    Original Author
    12 years ago

    It's definitely the governor vane. If I tighten the carb mounting bolts more than a few inch pounds or so, it deforms the carb and the vane binds.

    It's like metal spacers are missing, but I don't see any on the IPL.

  • ericwi
    12 years ago

    Glad to hear that you located the problem. It might have left the factory missing a spacer, or maybe they made some other change on the production line to fix this problem. No wonder you had difficulty finding the fault-it sounds like all the parts looked OK as is.