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

It's in decent condition, new rubber impeller, scraper bar and overall good shape. The guy I bought it from said it had been professionally serviced 2 years ago but had seen little use since then as he decided to hire a plow guy to do his average residential driveway. I could not get it to start after adding some fresh fuel that I brought with me so I offered him $ 40.00 and said OK. - he had it listed for $ 75.00 on CL. I'm pretty sure he left some old, unstabilized fuel in there and it turned into varnish.

I removed the top and back covers and dropped the fuel bowl. It looked like a bad batch of applesauce in there so I cleaned it out and shot the carb with carb cleaner and reinstalled the bowl. It fired up for a few seconds and then died. A good carb cleaning appears to be in order and I'm wondering if I can do this with the carb installed or is it easier/better to remove it from the engine (Suzuki 47P)? I've never removed a carb before but am mechanically inclined and would like to get this operational for next winter.

I remember Borat discussing a cleaning of the jets using wires to remove any build up inside that could cause fuel starvation. I have never done this so any suggestions or tips will be very much appreciated.

The float has to be free on it's pin and not pinched on the sides.   Maybe there's varnish inside the float hinge.   Find out what's binding the float.  Pull the pin and take off the float.  The resistance had to be in the hinge area.

The spring could be in correctly or incorrectly, I forget.  Most of the Mikuni carbs I've worked on did not have springs.  Maybe the spring is in backwards.  It does not matter.  What has to happen is the tension has to be small enought that the float alone can overcome it.  You said the flow stopped when you tested that so the tension is probably ok. 

When you have it like you are holding it and the float falls to its stop it's ok.  When you tip it over the float should be level with the bowl gasket rim.  That won't happen with yours because of the spring.  You can pull the spring can check where the flot ends up when the needle seats.

Looking into the choke side there are two internal holes that can be seen in the throat that should be prodded.  

You still have the minifold and gasket on.  Those should come off before tanking.   I think there will be 4 holes in back of the gasket which must be clean and prodded.

In the prior pictures it looked like the plastic bowl stop was cracked.

Do you have the jet that screws in by the bowl stop?

Did you take out the low idle feed screw on the top of the carb and clean it and in there? 

Also, the air feed screw next to it, the black one?   Those usually are brass and have a spring on the screw.  Never saw a black one.  It looks like the type that only has a hair of adjustment.  Maybe they are like the Hondas and have to be broken to get at the screw.  ??  If you can that one should come out and be cleaned and inside cleaned.

The needle does not go in a way other than the way it must go.   The only way it will fit into the hole and slot is the way it is in the pictures.  It's fine.  But it must move freely other than the spring tension.  It should be able to go up overcomming the spring by the force of the float lift from the gas rising.  You'll have to guess that. 

What you've cleaned is external parts which is essential to stopping crud from falling off and plugging something.  What matters is the passage passageways, ports and jets to be clean like the body.  The float looked like it had varnish.  The body looked like it had prior white aluminum powder buildup with a varnish cover on top.  Both are tough to deal with in hard to reach passageways.  If not white buildup then it's probably piles caused by the oil evaporation.  Two cycle gas evaporation can be very weird and many types depending on the gas, oil used and how the buildup happened.

You can test the float action as is by dunking what you have in a class filled with water.  Does the float raise and lower properly?   You can test how soon the float lowers the needle by putting on a 1 foot section of gas line and then fill that with water.  I test needles like that all the time for seating.  Get a class with a mount that is just big enough to sit the carb body on.  Then fill the gas line (pointed up).   You should be able to fill the tube and let it sit for an hour and the level not drop any amount.

SO:

1. Insure the float is freemoving.

2. clean the jet at the bottom of the tube in the center of the carb.

3. clean emulsion tube

4. clean the ports on the manifold side.

5. clean the jets by the low idle stop screw.

6. clean the ports in the choke side of the throat.

7 prod the holes on either side of the body.

Trouts:

Sounds like you're familiar with this carb.  I've never worked on one like that, so I'm not. 

I'm wondering, that the carb might cleaned properly but the screw settings might be out of adjustment.   Does this carb have an idle screw, a pilot jet with a pilot air screw and is there any control over the main jet? 

I'm kind of doubting there will be any control over the high speed circuit (main jet) but there might be a screw to adjust the low speed circuit (pilot jet).  Usually, the pilot jet is to be fully seated then backed out anywhere from 3/4 to 1.5 turns.  It it has an idle screw, it has to be turned in enough to allow fuel air flow to keep the engine running. 

>>>I'm wondering, that the carb might cleaned properly but the screw settings might be out of adjustment.

   Could be but I doubt it because of the things below - as far as adjustments.  His does not have a nut from the bottom like a Tecumseh nut with those two holes that get plugged all the time.  His had a solid nut.  The metering hold is on the jet that screws into the base of the tube that sticks down from the center of the carb body.   He's never shown it in the pictures.  If that's plugged it's like the nut holes on a Tecumseh being plugged.  And his has others - the 4 ports on the manifold side mentioned in another post and here.  You were right twice and still right.  He's got dirt someplace(s).

Yes, it has a low idle screw just like on a Tecumseh.  That’s the one that is a physical stop to the butterfly. 

There is also the gas feed low idle jet but it’s just screwed in.  It’s not settable like on a Tecumseh.  It’s got a screw like plug that screws in.  The bottom of the plug part has a hole in it which is the low idle metering flow control hole (jet).  

There is a high main jet on the top of the carb body.  I think the way it works is the high jet controls the flow of air which controls gas flow.  His has a plastic part I’ve never seen on a Mikuni.  It’s like the plastic stops on a Honda carb jet.  At least that’s what I think it is.  It’s a plastic stop so people can’t mess with it.  On a Honda you can break off the plastic and access the slot for the screw.  On his I’m not sure.  If his is a non-removable cover then that’s a problem for cleaning access and a positive for doing a dip.  BUT, I think the 4 holes I mentioned at the back of the carb on the manifold end lead to that jet.  He can prod and squirt in through those ports. 

Chances are pretty good that there is internal varnish buildup.  Frank, remember to separate the gasket and manifold before the dip. 

well by looking at the picture of the carb sitting upside down the float is setting WAY to low (its out of adjustment by a mile), it will run lean or not at all in that postion....when the carbs upside down the float NEEDS to sit parrelle to the carb base thats VERY important.

and of course as trouts mentioned the float ABSOLUTELY MUST move freely or it will not run.

And yes the SPRING is installed backwards from what l can see.

Niper99 - it's because of that spring.  If the spring was out it should sit parallel to the bowl rim when upside down.

 install the spring so it pushs the float TOWARDS the carb

Niper99, are you sure?  I think the spring it to insure getting needle off the seat. 

nope lm 100% on this one..he could try and run it with the spring off if he wants and will should run but l suspect it could  possiably cause flooding if ran all the time with out the spring.

now that l see the carb lve work on alot of these, and some have the spring and some dont...not really sure why...but tecumseh does the exact same thing..l do know that tecumseh did it because they had flooding issuse on some of there carbs or a rich condition...(sputter)  

I've never seen a float with a spring to force it in either direction.  If I were Frank, I'd take it off just to see how things work without it.  The way the spring works in his set up is to force the float down thus ensuring the needle drops allowing fuel into the float bowl.  That will not cause a lean condition.  If anything, it might limit the ability of the float to fully close the needle.

Regardless of the float/spring issue, I'm with Trouts.  There has to be some tiny orifices and galleries plugged. 

Trouts, the hollow piece in the center that the main jet screws onto is sometimes called the diffuser.  Most of the ones I've seen have very tiny holes drilled across the tube.  As you have said, they also must be cleaned.  Personally, I think it's the orifices in the venturi that are blocked.  Nonetheless, he should pull the diffuser to ensure it's clean.