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  1. #1

    Join Date
    May 2010
    Posts
    2
    Location
    Texas
    Mower
    Toro and Murray rider

    Unhappy Why carb rebuilds don't work

    I've had bad experiences rebuilding small engine carbs. First, an older tiller with a carb with a diaphragm which I meticulously cleaned and installed the rebuild kit on. It sort of ran for awhile. Then I rebuilt my Sears 6.5HP OHV pressure washer. First time I cleaned it out with carb spray and canned air- all the ports, everything. Didn't fire. Next time, I did it again, this time <SOAKING> the carb for 12 hours after removing all the plastic, rubber parts, and using my compressor air. Replaced it, no dice. Ordered a replacement carb for $40 and it fired right up. I am <very> meticulous about taking things apart, read all the tips about tiny orifices, etc. The pro at the lawnmower shop said they soak their carbs all night while AGITATED. I'm wondering if that's the magic. Read somewhere that the newer carbs are made with potted cheap metal and they get corroded and its very difficult to "clean" them. Bottom line is, does anybody know what the top 3 or 4 errors or tips are in rebuilding small engine carbs that will be successful ???? I'm almost to the point where next time a small engine quits firing, once I've checked to make sure I've got a good spark, fuel line is clear and brand new top quality gas, and air filter is clean, just ORDER another replacement carb and be done with it !!!! Not worth the time, expense of a rebuild kit, and frustration....

    Bob

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  3. #2

    Join Date
    May 2010
    Posts
    6
    Location
    Alabama
    Mower
    John Deere

    Re: Why carb rebuilds don't work

    I'll agree with that way of thinking. As soon as your crack it open, you seem to develop problems. A new carb is probably the cheaper way to go.

  4. #3

    Join Date
    May 2010
    Posts
    1
    Location
    Oklahoma
    Mower
    Z38

    Re: Why carb rebuilds don't work

    I know this goes against conventional wisdom, but one thing I have found over the years is that I do not have any luck storing my small engines over the winter with no gas in them. Seems like more times than not my carbs leak or they just don't run right when I fill them back up. I like to leave them full of gas with stabilizer. That way, there is no condensation in the tank over the winter. If I can I also run them several times over the winter, all though I never start my weed eater motors in the winter. Never had any trouble with this method.
    I have an old Troy Bilt Horse tiller that I put a new Briggs motor on when the Tecumseh died. I messed up one winter and let it go dry and set all winter. It wouldn't run for squat the next spring. The carb was only 1 year old, so I knew it was only gummed up somehow. We have an small ultrasonic cleaner at work. I believe the cleaning solution in it is isopropyl alcohol. I counted the number of turns the needles were out from stop, and then removed them. I disassembled the carb and left it in the ultrasonic cleaner all night. Put it back together the next day with the same gaskets and it ran as good as ever. That was the first and only time I have ever had a successful small engine carb overhaul.
    Speaking of the old Troy Bilt Horse, are there any other Horse owners here? I am all ways interested in talking to other owners about what it takes to keep these old machines running. Where you find parts, etc.

    regards
    Curt

  5. #4

    Join Date
    May 2010
    Posts
    1
    Location
    Oklahoma
    Mower
    White

    Re: Why carb rebuilds don't work

    I've had the same experiance. Had a mini tiller and didn't use if for a year. Did the carb clean and rebuild and it just wouldn't run right. Ordered an new carb and all is well. I've rebuilt car carbs with no problems but these small ones can be a pain. I now put Stay-bil in the gas cans before I even fill them up so that way I know it in there. Just moved to the country (57 acres) in Nov so now I have a few gas powered engines to keep up with.

    Curt, I have a 74 vintage Troy-Bilt Horse with the Techumseh engine on it. I've owned this tiller since 1980 and has been in and out of storage many times as I was in the AF for 26 years moving around a lot and some places I could use it and others it stayed in storage.

    Now that we are in the country again and have a garden out comes the ol Horse. It's been 6 years since it was fired up. I put gas in it and immediatly it leaked out the carb. Pulled the carb apart and it was varnished up pretty good. Took it apart and brought it in to drop in the ultrasonic cleaner I have in my office. In the mean time I head to my buddies lawn mower shop to see about a rebuild kit. Find out Techumseh is no longer in buisness and not kit available. Great! So I take what I have in had, put it back together, fill it with fuel and BAM, starts right up! Couldn't till with is as the belts are too stretched but I was amazed that it fired right up. I will order some new belts and use it between the rows on the field.

    Great to see a new board stand up for lawn mowers. Right now I have a NH TC45DA with brush and finnish mowers, Honda push mover and a small White riding mower I traded out for some dirt work. I plan in the future to get a dedicated ZT mowing machine and want to go with a deisel. Latest toy I picked up is a V30 Ditch Witch that guess what.....needed carb work.

    Looking forward to reading reviews and thoughts on ZT mowers.

    Greg
    "Everyday Above Ground is a Good Day"

  6. #5
    Bruce Mowbray's Avatar
    Join Date
    May 2010
    Posts
    10
    Location
    Pennsylvania
    Mower
    Husqvarna

    Re: Why carb rebuilds don't work

    I have had great success with rebuilding small carbs. The most important thing is to clean out the tiny holes in various parts of the carb to their original size. I use a gauge pin set that goes from .002" to .062". I start with the smallest pin that will go through the hole and push out the varnish and gunk. I keep going to the next size up in .001 incrments until the pin will not go through the hole without pushing very hard. A little gummout carb spry helps to loosen and really baked on varnish.


    Bruce Mowbray
    Springville, PA

  7. #6

    Join Date
    May 2010
    Posts
    2
    Location
    Texas
    Mower
    Toro and Murray rider

    Re: Why carb rebuilds don't work

    Thanks for the ultrasound cleaner tip Curt. Harbor Freight has cheapo ones for sale, so I'll try it. And ditto, thanks Bruce for the tip on hole cleaners. I'm pretty sure I'd always get them cleaned out since I could see stuff coming out when blowing air into the apertures after soaking, but you never know. And some of them make turns and you're not sure you got inside well enough. I guess that's why the pro told me they soak 24 hours and AGITATE. Of course I get plenty agitated every time I try these rebuilds And I too have been successful rebuilding car carbs (notably my old MGA) so I know I'm not a klutz. Its just that these small engine carbs are apparently VERY finkicky.

    Thanks to all for responding, and happy rebuilding ! May the Force be with you.

    Bob

  8. #7
    essasmallengines's Avatar
    Join Date
    May 2010
    Posts
    42
    Location
    Ontario, Canada
    Mower
    John Deere

    Re: Why carb rebuilds don't work

    One other thing to remember is often passage ways are tapered from wide to small exit when using carb cleaner or air remember to always blow from small opening to large, that way you won't really plug the hole up by blowing dirt further down the passage way and packing it in harder!

  9. #8

    Join Date
    May 2010
    Posts
    7
    Location
    Maryland
    Mower
    John Deere

    Re: Why carb rebuilds don't work

    On the Troy-Bilt - I have an '80s vintage Horse with the Briggs engine. I have had good luck finding parts on line, but don't have a good reference at hand. I had to replace that rubber coated reverse hub (not sure what it is really called) and got that plus a new improved detent mechanism.

    I have had fair sucess with carb rebuilds - guess i am doing something wrong? :-)

    One problem I have had with a number of engines is loose carb mounting screws. They do vibrate loose, and I often don't think to check them until I have checked everything else. I have had that on my Troy-Bilt, JD garden tractor, chainsaw, Ford NAA tractor ...




    Quote Originally Posted by Gregkabob View Post
    I've had the same experiance. Had a mini tiller and didn't use if for a year. Did the carb clean and rebuild and it just wouldn't run right. Ordered an new carb and all is well. I've rebuilt car carbs with no problems but these small ones can be a pain. I now put Stay-bil in the gas cans before I even fill them up so that way I know it in there. Just moved to the country (57 acres) in Nov so now I have a few gas powered engines to keep up with.

    Curt, I have a 74 vintage Troy-Bilt Horse with the Techumseh engine on it. I've owned this tiller since 1980 and has been in and out of storage many times as I was in the AF for 26 years moving around a lot and some places I could use it and others it stayed in storage.

    Now that we are in the country again and have a garden out comes the ol Horse. It's been 6 years since it was fired up. I put gas in it and immediatly it leaked out the carb. Pulled the carb apart and it was varnished up pretty good. Took it apart and brought it in to drop in the ultrasonic cleaner I have in my office. In the mean time I head to my buddies lawn mower shop to see about a rebuild kit. Find out Techumseh is no longer in buisness and not kit available. Great! So I take what I have in had, put it back together, fill it with fuel and BAM, starts right up! Couldn't till with is as the belts are too stretched but I was amazed that it fired right up. I will order some new belts and use it between the rows on the field.

    Great to see a new board stand up for lawn mowers. Right now I have a NH TC45DA with brush and finnish mowers, Honda push mover and a small White riding mower I traded out for some dirt work. I plan in the future to get a dedicated ZT mowing machine and want to go with a deisel. Latest toy I picked up is a V30 Ditch Witch that guess what.....needed carb work.

    Looking forward to reading reviews and thoughts on ZT mowers.

    Greg
    "Everyday Above Ground is a Good Day"

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