Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Went to replace a carb I recently cleaned up, only because I thought having a new carb would be an assurance that the blower would be good to go and reliable when on demand.

Bought what was supposed to be an original Tecumseh part on Amazon, but received one made by Ruxing. 

Does this brand work OK, or should I replace with the real OEM? 

I just bought an Oregon replacement carb for a Tecumseh HM80. The seat is brass and the needle has a rubber tip on it, the opposite is the OEM carb . I have never had good luck replacing the rubber seat. Don't get it seated correctly and gas leaks by resulting in in a pool of gas on the floor if you forget to shut off the gas line valve.


 I installed the carb today and found that it was a little touchier to adjust than I am used to. I put it on a blower I just picked up and did not put a lot of time in to it so it may have other problems, but it did run ok with the new carb. I went out to the garage later and there was a pool of gas on the floor below the carb.


 I need to put some time in and figure out what's wrong. I am still hopefull that the needle and seat design on the Oregon will work better.

True most of the time you can put a kit in the original carb and your all set..I must have had mine apart 4 times and the machine just would not run right with it. I even had the welch plugs out.And i have rebuilt a lot of automotive carbs to.Anyway with the Oregon carb it runs perfect

Borat: I could have cleaned at least two carbs in the length of time it took me to read it.

     You could have but not him.  He seemed like he might go for it if he knew how so I wrote it up.  I have a couple part write-ups around but I’m a pretty fast typist so blasted it out.  I should work on it and keep it as a master to post when someone is looking for carb cleaning info. 

Eleckster: I just bought an Oregon replacement carb for a Tecumseh HM80. The seat is brass and the needle has a rubber tip on it, the opposite is the OEM carb

   Never heard of that before but I have never bought a new carb.   For the few I’ve had to toss over the last several years I have a stock of cleaned carbs from dead engines.   At least to me I would not consider that a replacement carb and send it back.   What’s the part number of your replacement?

>>I have never had good luck replacing the rubber seat.

    Did you have the ribs of the seat facing into the carb, check the needle clasp was on correctly, check the float on the reinstall and flush the tank and line?

    Seating a seat can be an issue without a carb seat tool but a seat size punch will work the same.  I've had problems with aftermarket seats so these days use only Stens and Tecumseh.   If you scrape the seat area wall on the install it can dislodge a miniscule particle.  You can also introduce a tiny particle if you don't clean the tool and seat before the install.  Those things are rare but all it takes to muck up the needle from fully covering the seat. 

First and foremost, thanks for the help.

trouts2:  Did just about everything you wrote and suspect the issue was in your #4, the two small holes in the throat.  I could readily probe one, but not the other.  It took a stiff thin diameter steel wire (.016, I think) bent to 90 degrees to do both.  That's a concern, that I pushed something into the welch cavity and it may come back to haunt.  And I later read that the float spring is directional and don't know if I should, but probably will regardless just to check things out, make sure it's on with the open end facing the right direction.

After reading the comments posted, I took a look at the after market fuel valve needle with the rubber tip side by side with a OEM part.  It looks to me, and I could be wrong, that the needle with the rubber tip (can it be called a needle if it has a rubber tip?)  is stamped or molded with an OK looking but crude stem, while the OEM needle appears machined with much more precision.  It's just the retired engineer in me being curious.

I'm fully capable of handling the carb repair, and would have been all set if it came with instructions.  It's all the questioning that I do, unlike the typical DIY'er, that's my stumbling block.

After reading all here, am tempted to keep the now working OEM carb in place and have the unused Chinese one on the shelf should it ever be needed.  I'd also like to find out how old this motor is, and if has points or solid state coil.

I saw one on Ebay with the Stens name advertised, and the Ruixing trademark on it in the photos.  Is it the same?

Cheers.

The replacement carb is Oregon 50-642.  I like the brass seat with rubber needle.  That setup, in my experience, is more reliable.  I work on half a dozen small engines a year so the small number could lead me in the wrong direction.

 

The Oregon carb has a plastic float that is very difficult to adjust, as the metal tab that holds the seat clip breaks off if much force is applied.  I’m thinking that I may swap in the brass OEM float if it fit and see how that works.

 

There are probably more failures caused by me than can be blamed on the design.  The seat is installed with the rib facing down.  I do not have the tool.  I asked the dealer for the tool but they did not stock it.  Currently I’m using a transfer punch with the end buffed smooth, which is just slightly smaller than the hole for the seat. I recently read a reference in “Small Gas Engine Repair” by Paul Dempsey, to be sure there is a fuel shut off if the seat is elastomer as they leak.  This made me feel better as misery loves company.

 

I have had some carbs fix themselves by running.  I’m guessing that the seat settled in.  I’ve also slowed the leak down by adjusting the float so that it is a little higher than flush.  My theory is that as it over fills it puts more pressure on the seat.

 

I’ve read that there is an orientation to the clip that holds the needle, however I can’t figure out why this is? It looks like it will operate the same either direction.  I forgot what the orientation is, but if I knew I probably would put it in wrong to see if it caused a problem that could be fixed by turning it around.  I have turned it around trying to fix a leak with no success.

 

What if you took the OEM needle and lapped, or peened it into the brass seat?

 

Obviously I suffer as well from the questioning issue as well:-)

It's written that the open end of the float needle faces toward the air in side.  Something about possibly binding if it's reversed.

Funny, you're having a good time with the rubber tip needles because the OEM design failed, I'm treating the seat of the OEM with respect (blew air into it, not against it while cleaning; the reverse of what trouts2 wrote but the result is the same) because it's never failed and look at the rubber tip design with trepidation of change.

Started it up today for the fun of it.  One pull!  Then I underchoked it for a quick stall but still started right up again.  As written above, it's a fussy little bugger.

How can I tell if the engine has points or is solid state?

>>and have the unused Chinese one on the shelf

    Or return it and get a used OEM from a dealer.    Some dealers keep a box full. 

>>I'd also like to find out how old this motor is, and if has points or solid state coil.

    Solid state.  The coil is above the flywheel  on models which use the Tecumseh carb that crosses to the Stens number. 

Sort of interesting side note is the Stens part is listed for 8 & 9hp’s and the OEM number it replaces 8hps only.

>>I recently read a reference in “Small Gas Engine Repair” by Paul Dempsey, to be sure there is a fuel shut off if the seat is elastomer as they leak.

    Weird as that basically means stretchy,  rubbery, returns to it’s original shape…    There are many  millions of Tecumseh engines out there with rubber like seats that are fine and most for many years.  Given the low presssure of the float I doubt a hard seat would work. 

>> I’ve read that there is an orientation to the clip that holds the needle, however I can’t figure out why this is?

   The clip points to the throat opening.    I’ve installed both ways and never noticed a difference. 

Trouts,

I have to rebuild a diaphragm type carb this weekend.  Ive never done that before.  Any resources or tricks you can point me towards?

It is a tecumseh 632117

Dan

   No real advice.  For diaphragm type I usually don't get a kit, just the diaphragm. 

   Exploded view of that carb:

   http://www.partstree.com/parts/?lc=tecumseh&mn=CA-632117&dn=CASERIES_071632117-CA

   Decent service manual on diaphragm types at the Walboro site:

   http://www.walbro.com/servicemanuals.aspx

kdez,  Short tips on your rebuild.  Pay attention to the "F" designation on the carb body, it dictates whether the gasket or diaphragm go against the bottom plate.  Sand lightly or wire wheel the bottom plate as clean as you can get it.  It's junk metal and won't shine, but you can't have any white powdery residue looking crap left, especially at the edges of the gasket/diaphragm engagement surface!
Make sure the metal side of the diaphragm is up toward the needle valve, otherwise when you blow the air into the primer line it won't go up and hit the needle valve to release fuel. 
Don't know on your specific one, but the main jet nut size is likely 9/32" and a fat, cheap socket won't fit right and you can strip it easy........I say from experience :-)
When you remove the main jet/needle seat make sure the washer (usually part #56 in diagrams) comes out with the old stuff.  If not, look around in there, it'll drive you nuts upon reassembly if it it's still in there!
Pay special attention when "probing" with wires or blowing air INTO or OUT OF the main fuel inlet.  There is a check valve in there between the hose nipple and carb body.   On the oldie style Toro S-200/620 carbs, that part is no longer available.  You can kill it easy with a wire probe thinking you are feeling blockage........I say from experience :-)