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? 

  What's the issue with cleaning?   Crapped up carbs rarely need to be tossed unless there is metal damage from rot of various types.  Buildup of varnish even nasty buildup on a two stroke left in a warm place with a full tank of gas can be cleaned. 

Well, for you trouts2, it's easy and you have a lot of experience and I appreciate reading your posts.

For first timers like me, it's a big deal and a mysterious blob of metal that only raises questions of like, where's this hole go to and how's that work?  And then there's that supposedly OEM rebuild kit in a baggie that doesn't come with instructions and although someone like myself can look online and seemingly think good to go, there are small things overlooked hindsight - not even mentioned in cursory directions and later discovered - like which way the inlet needle spring should face when reinstalled.  Darned if I know if it's in the right way and subject to binding.

So it's a matter of confidence in the fixed carb and knowing it's not used much and HEAVILY relied on after blizzards.  There's a comfort in knowing it'd work properly.  I still don't know if we're better off with the cleaned out 10 year old carb or a replacement.  I do know I don't want to be let down right after a blizzard. 

The blower did well clearing 6" recently, and choked on the end of driveway slush as always (chute looks like coarse floor sanding paper on the internal bend and it's hopeless).

I simply don't know if cleaning the carb without removing the Welch plug is a good way to have gone and don't mind replacing the whole thing if called for.  I've never removed/replaced a plug and haven't seen instructions for doing it.  I assume some special tool knocks it in place, and another special tool is needed for placing the fuel inlet gasket.  I didn't do either because of that.

The China carb abounds online, the OEM looks hard to come by and I really don't know which road I should travel on this one.  Leave as is, take it apart again and go deeper or replace the darned thing.  If the latter, I don't know with what.

I think it's a 1994 engine on a 1969 (44 year old) Ariens and, like an old friend, I really want to keep it going.

Axis:

Nothing ventured.  Nothing gained.  I'm with Trouts.  I've never met a carb I couldn't fix with a piece of wire, can of WD-40 and compressed air in most cases.  Once in a while I'll put in a kit. 

The way I see it, at least the effort should be made to get the old carb working.  If that fails, resort to buying an new one. 

At the very least, you've gained a bit of experience on the workings of a carburetor and if you managed to get it working, that would be a good "confidence" builder.

   If you’re up for it the people on the forum will get through cleaning your carb.   It was not that long ago that I thought spraying carb cleaner into the throat was a tuneup.    If you go through one then you can do most any carb in the future.

  Welch plugs are mysterious and that’s all.  The plug comes out by piercing the plug and prying it out, clean in there and press in a new one.   No special tools.  There’s just holes in there so nothing special.  If you have a sharp chisel it makes it easy.   The Welch plug area is often mentioned when troubles persist after cleaning but the chances are about 80 or 100 to 1 that it is.   About the only time the Welch area would be a problem is if the carb has metal rot especially the white aluminum crud buildup but at that point the carb is often too far gone to bother with.  It’s very rare to come across a carb in that condition.  So the upshot is forget Welch plugs. 

   Cleaning is fairly straight forward and remembering where things went.   Taking pictures with a digital camera helps.  A big problem is remembering how the linkages were setup before taken apart.  But they can be noodled through, as in there are only so many places at either end of a spring, governor rod or throttle rod can go.   

    I’m no sure which model 8hp you have but there is probably no spring to remove, a long rod between the governor arm and throttle and another from the governor arm to the throttle plate on the carb.  There’s only a couple of choices for holes on the throttle and throttle plate.  My be you know where those go so no issue.

   The bowl comes off by the bottom nut and there’s a needle going into that.  The needle has a metal washer, a rubber gasket ring and a spring.  The nut has a few holes depending on the carb but usually one or two larger holes near the base, one or two higher on the flat between the threads and one inside.  All those are prodded with a stripped tie wrap, sprayed with a carb cleaner and washed out with air.  If you don’t have air that’s ok.  The high pressure of the carb spray is enough. 

    There’s the low idle needle which also has a spring, metal washer and rubber gasket.  Back that out and spray in there with carb cleaner.  

    On the bowl side of bottom of the carb there float on a hinge with a needle attached to it with a clip.  Pull the retaining rod out and remove the float, clip and needle.   Put all these parts and the ones above into a cup or dish.

    Up in the area where the needle went is a rubber seat for the needle.  You can pull the seat out with a tool that has an end like a crochet hook – it has just enough of a dull barb to catch the far end of the seat to pull it out without tearing it.  You probably don’t have one and for the first attempt can leave the seat in.  If things are weird after cleaning then you can get the seat out with a thin pick.  There will be a replacement in a kit.  The seat goes in ring side in first – one side has rings the other does not.   By the way least for me kits are expensive and useless.  The metal parts are not needed and the gaskets iffy on most rebuilds.   For a cleaning I usually put in new o rings on the high and low jets, a new bowl gasket and a new seat.  Since you can’t get seats as a single item they come in packs usually with a needle so I put in a new needle also but they are almost never needed.   Packs usually come with seat, clip and needle,  or  those and an a bowl gasket.    Gaskets I buy by the 20 pack or from a hardware store.  Those are all that’s needed for rebuilding a carb = seat, 2 O rings, bowl gasket, needle.

   There’s a few places to prod in the carb.  

1.       1. The flat on the outside of the carb ½ in to the right above the low idle screw.  That’s the air vent.  Prod in there with the tie wrap.  Spray into the square hole on the bottom of the carb by the bottom Welch plug.  You should see spray come out of the hole on the flat.

2.       2. Spray in to the hole where the gas line was attached and spray should come out where the needle went.

3.       3. But some Z bends into the tie wrap and push it up into the center post which holds the emulsion tube.   Spray in there and look into the throat to see if the full spray is coming out.  If you look in through the bottom of the tube and put the throat in bright light you can see light through the tube.

4.       4. Prod the holes inside the throat.  Depending on the carb there will be 2-3 holes close together  opposite the outside Welch plug.  Bend the tie wrap.

5.       5. If there’s a vent hole by the base of the butterfly prod there and spray.

6.       6. Your carb may have a hole(s) up higher to the right or left side of the butterfly, prod in those and spray.

7.      7.  Spray into the primer port, there the thin line ran to from the primer bulb.  Spray should come out from below.  

8.       8. Unless I missed something that’s it.  I usually dip all carbs overnight before the above but that’s not essential. 

Assembly:

1.       1. Put the spring, washer and gasket on the high speed jet.

2.       2. Screw the jet assembly into the nut.

3.       3. Put the spring, washer and gasket on the low speed jet.

4.       4. Put the bowl gasket on the carb rim.

5.       5. Put the clip on the needle and set it on the float tab.

6.       6. Put the float in place and insert the rod.  Check that the float is parallel with the rim.  That should work out to 11/64 ths.   If there are problem running later this may have to be revisited.

7.       7. Put the float on with the rod.

8.      8.  Put the bowl on with the nut and high speed jet attached.

9.      9.  Screw in the low speed assembly. 

Mounting the carb:

1.      1.  Install the throttle to governor linkage rod, probably not removed.

2.       2. Install the governor to throttle linkage rod, governor arm first then into a throttle plate hole.  As you look at the carb it usually be the hole to the left on the far side. 

3.       3. No springs on yours I think, they stayed on.

4.       4. Press on the fuel line and clip.

5.       5. Attach the primer line.

6.       6. Attach the carb to the block.   By the way it’s usually easiest to remove the carb with the manifold inplace rather than at the manifold carb bolts.

I probably missed something but that will likely get you a start and several years of reliable operation from the carb.

Excellent walk through Trouts.

I could have cleaned at least two carbs in the length of time it took me to read it.  I am a slow reader though.

But all kidding aside, a simple carb could easily be cleaned in the length of time it took you to write that!

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:-)