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  1. #1
    Silver Member
    Join Date
    Feb 2008
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    121

    Default Robin valves

    My 22hp robin has about 700 hours on it and lately I was thinking it was close to replacement time. Hard starting and a general lack of power were causing me to think it was about gone. So before I forked money and time to buy and replace the Robin I decided to run through all the maintenance items I could think of. Cleaned the carb, replaced air filter, changed spark plugs changed fuel filter, and checked the valve clearances. Wow was I surprised at how much slop I found in the lifters. So I reset the clearances and fired it up. It started and ran like new with power I had not felt in some time. All that was really not hard and I admit should have been done long ago. Good news is that the robin is strong again and I saved some money.

  2. #2
    Epic Contributor MossRoad's Avatar
    Join Date
    Aug 2001
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    22,975
    Location
    South Bend, Indiana (near)
    Tractor
    Power Trac PT425 2001 Model Year

    Default Re: Robin valves

    I've heard that about the valves on the Robin several times here in the PT forum. And everyone that does that maintenance is really happy with the results. Makes me want to check my Kohler as soon as it warms up.
    MossRoad

    Click On My Little Tractor
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  3. #3
    Veteran Member
    Join Date
    Mar 2007
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    1,140
    Location
    Bay Area, CA
    Tractor
    Power Trac PT1445

    Default Re: Robin valves

    I think that valve clearances is an often overlooked service item in engines. I remember changing cars from an engine with manually set valves to ones with hydraulically set lifters- what a difference. (same model, about four years apart in age) It always stayed in peak form. Basically the same engine, just tweaked.

    I can't say that it is my favorite service item, but it is well up on the ratio of reward to effort.

    The same is true for generators, chippers, rototillers...

    All the best,

    Peter

  4. #4
    Epic Contributor MossRoad's Avatar
    Join Date
    Aug 2001
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    22,975
    Location
    South Bend, Indiana (near)
    Tractor
    Power Trac PT425 2001 Model Year

    Default Re: Robin valves

    Once I helped a friend rebuild an engine with solid lifters. That was a good education. Mine had hydraulic lifters. And I'd run them out of oil at extremely high RPMs. Without anyone ever explaining the difference, one would never know how it operates. I strongly suggest everyone take the opportunity to tear down a couple different engines sometime in their lives just to see how they work, why they failed, what keeps them going, etc... really interesting stuff that we all take for granted most of the time. Also, check the differences between two-strokes and four-strokes. Another education worth pursuing.
    MossRoad

    Click On My Little Tractor
    To See Pictures And Videos
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  5. #5
    Super Star Member J_J's Avatar
    Join Date
    Sep 2003
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    16,677
    Location
    JACKSONVILLE, FL
    Tractor
    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Robin valves

    You know there is wear and tear. How about the valve guides, valve seats, do they every wear or pit.

    This is some data from the Kohler 25

    Valves and Valve Lifters
    Hydraulic Valve Lifter to Crankcase Running
    Clearance
    0.0241/0.0501 mm (0.0009/0.0020 in.)

    Intake Valve Stem-to-Valve Guide Running
    Clearance 0.038/0.076 mm (0.0015/0.0030 in.)

    Exhaust Valve Stem-to-Valve Guide Running
    Clearance 0.050/0.088 mm (0.0020/0.0035 in.)

    Intake Valve Guide I.D.
    New
    Max. Wear Limit
    7.038/7.058 mm (0.2771/0.2779 in.)7.134 mm (0.2809 in.)

    Exhaust Valve Guide I.D.
    New
    Max. Wear Limit
    7.038/7.058 mm (0.2771/0.2779 in.)7.159 mm (0.2819 in.)
    Valve Guide Reamer Size Standard 0.25 mm O.S.
    7.048 mm (0.2775 in.)
    7.298 mm (0.2873 in.)
    Intake Valve Minimum Lift 8.07 mm (0.3177 in.)
    Exhaust Valve Minimum Lift 8.07 mm (0.3177 in.)
    Nominal Valve Seat Angle 45ー
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  6. #6
    Veteran Member
    Join Date
    Mar 2007
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    1,140
    Location
    Bay Area, CA
    Tractor
    Power Trac PT1445

    Default Re: Robin valves

    Great to have the numbers. Once I start looking at wear in some of those things, I'm replacing the whole set. I guess I'm just lazy; I'd rather go through the exercise of tearing the engine down once, and move on... But everyone is different.

    All the best,

    Peter

  7. #7
    Platinum Member
    Join Date
    Jan 2005
    Posts
    629
    Location
    SW Virginia
    Tractor
    PT425

    Default Re: Robin valves

    My Robin 25hp is weird about valve clearances. I've been an automotive mechanic since the late 70's, and on nearly every engine that required valve adjustments, the exhaust valves get tight and the intakes get loose between adjustments. The Robin does the opposite. The exhaust valves stay about the same or get a trifle looser, but the intakes tighten up to the point of not quite closing at all, which makes the engine run really lousy at idle.

    At 1100 hours, I've just done my fourth valve adjustment. Once again, I'm surprised that the engine will actually stay running at idle. I guess I'm a slow learner

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