Husky 346 rebuild problem for a newbie...

tkshrout

tkshrout

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Hi All,

I just mounted a new top end to turn a 350 into 346 using an oem 346 piston and cylinder. I really flooded it the first time I tried to start- had fuel coming out of the muffler.

I let it sit with the plug out overnight and was able to get it started the next day, but am now experiencing a new problem: the saw runs and sounds good (even sits at idle) but spits a lot of smoke once warm. It still looks like fuel is coming out of the muffler. I took the muffler off and it looks wet inside. I dried the muffler thinking it was from the first flooding, but same issue on a second start.

I'm hesitant to let it run for fear of ruining the new top end. Any ideas what could be causing this? I'm not sure whether to look at the carb or the cylinder.

I'm surprised that fuel could be blowing through and have the saw still run and idle. Fuel is a pre-mix 40:1, but not husky or stihl branded...

Any help would greatly appreciated- this is my first rebuild, and its a family saw.

Thanks,
Tim
 
Motherboard

Motherboard

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Did you service the carb or adjust it, is it adjusted correctly.
How did you flood the saw after the rebuild, is the choke linkage working,
opening and closing as it should. What happened the original top end on the
saw, was there a problem that destroyed it, if so did you fix this problem.
What oil are you running.
 
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a. palmer jr.

a. palmer jr.

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Several things might cause this: As mentioned, carb adjustment, inlet needle too high, choke linkage sticking. You mentioned that it was running pretty good so the ignition is probably okay unless the flywheel is slightly retarded, making it fire a little late...
 
tkshrout

tkshrout

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I can answer a couple of these now and a couple in the morning.

The flooding happened cuz I just kept pulling on full choke. The saw I’m used to (poulan) full fires on full choke, then half. This one didn’t so I just kept pulling…

Saw was fried after running straight gas.

The carb limiters are in place so I can only get like a half turn. If the carb could be responsible i can cut the limiters and try full adjustment. What I’ve seen is to screw them all the way in then out 1.5 turns and start from there?

thanks for the help to date
 
a. palmer jr.

a. palmer jr.

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You might try a little less than 1.5 turns. On some saws it's just one turn and some of the others it's 1.25 turns out. I usually take the limiters off, not telling you to.
 
Motherboard

Motherboard

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If the saw fired up and ran, and did so with a lot of smoke,
we can assume it got too much fuel, or it over heated and is smoking
as a result, this can be confirmed by taking off the muffler and looking
to see if any damage, like scores are visible on the side of the piston,
the cylinder walls and such, look if the ring is ok, not broke or chipped.

Change the plug for a new one first, as they actually can fail under load,
a plug not firing under load will certainly cause the smoking issues mentioned.
Its a cheap test and you have a backup plug if all is well with the old one.

If all is well, then a pressure test on the carb is required to eliminate or
confirm the metering valve is stuck open or opening too easily and causing
excess fuel to get into the engine, this needs to be done.

If that does not solve the problem, then maybe the coil, which will be more
expensive to replace will need to be investigated, some coils will work under
low compression, then fail as it rises, or fail as the coil heats up, thus will start
the engine but it will run badly.

Why did the saw need a new top end, I ask because there could still be a problem
that has not been addressed that resulted in the demise of the previous cylinder or piston,
and may destroy the new one as well, such as a fly wheel that is not timed, owing to moving
around on the shaft, a sheared key, a loose nut holding it on.
Also, did you put the new piston in facing the correct way, the arrow pointing towards the exhaust side.
 
old CB

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Each time I've mounted a new top end on a saw, on first startup it smokes like holy hell. Because you oil everything as you assemble. It takes a minute or two for all that stuff to burn away. If you shut it down immediately out of concern--not a bad reaction--you may not have burned off the extra stuff inside.

If you've done everything correctly, you should be able to let it run 2--3 minutes, in which time you'll likely see things clean up. I'm just half a mechanic, but I believe your greatest risk with 2-strokes is a lean running condition, which you probably don't have if you're blowing smoke. So give it some time to burn off.
 
quattro.pilot

quattro.pilot

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OEM break-in adjustment for carb is 1 turn out for both L & H. You are supposed to run the saw like that for something like 10hrs...then fine tune. You likely won't make more than a +/- 1/4turn adjustment at that point to either jet, and I've found more often than not both end up tuning a hair leaner (clockwise turn).

So that's where I'd start. Pull the limiters, readjust to 1 turn out, and see where you're at. Carb kits are so cheap & easy too that you probably should have done that just on spec since you had the entire top end off. You could have a shitty diaphram which isn't metering properly.

Spitting out fuel from the muffler is definitely a over rich situation....and your most likely culprit is the carb.
 
tkshrout

tkshrout

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To answer some of the suggested things to check-

-the choke linkage is functioning
-Piston arrow points towards exhaust side. Attaching pictures of current state seems to be fine to me.
-I’ll have to look up pressure testing a carb.
-I’ll have to get a new spark plug.
- I’ve not rebuilt a carb before- this one is a Zama el18. Looks like a rebuild kit should be about 20?

I did remove the limiters. Do I run a large risk trying to readjust the carb without the limiters and start it again?
 

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a. palmer jr.

a. palmer jr.

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It's no risk running without the limiters if you turn the screws at least one turn out each. If you're leery about rebuilding carburetors you can buy a new one on ebay for less than the cost of a kit if you don't mind am stuff. I use them all the time and have been very happy with them..
 
grizz55chev

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To answer some of the suggested things to check-

-the choke linkage is functioning
-Piston arrow points towards exhaust side. Attaching pictures of current state seems to be fine to me.
-I’ll have to look up pressure testing a carb.
-I’ll have to get a new spark plug.
- I’ve not rebuilt a carb before- this one is a Zama el18. Looks like a rebuild kit should be about 20?

I did remove the limiters. Do I run a large risk trying to readjust the carb without the limiters and start it again?
If no pressure-vac test was done on the saw before or during disassembly, you really need to do it now..
 
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Motherboard

Motherboard

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To answer some of the suggested things to check-

-the choke linkage is functioning
-Piston arrow points towards exhaust side. Attaching pictures of current state seems to be fine to me.
-I’ll have to look up pressure testing a carb.
-I’ll have to get a new spark plug.
- I’ve not rebuilt a carb before- this one is a Zama el18. Looks like a rebuild kit should be about 20?

I did remove the limiters. Do I run a large risk trying to readjust the carb without the limiters and start it again?
Rebuilding a carb, its a Walbro, but they work the same for the most part
Be careful the order you put the diaphram and gasket back on, the gasket always
goes next the carb body the diaphram then goes on top of the gasket. It should show
this in the video, if you get them wrong you wont be running too well if at all.

On the other side of the carb, there is a gasket and a flap of material with small
tongues on that flap, they are assembled in the opposite order, flap of material sits on
the carb body, followed by the gasket. Only saying because it can easily be over looked
by someone who never assembled on before, and will drive you nuts.
 
rking453

rking453

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Each time I've mounted a new top end on a saw, on first startup it smokes like holy hell. Because you oil everything as you assemble. It takes a minute or two for all that stuff to burn away. If you shut it down immediately out of concern--not a bad reaction--you may not have burned off the extra stuff inside.

If you've done everything correctly, you should be able to let it run 2--3 minutes, in which time you'll likely see things clean up. I'm just half a mechanic, but I believe your greatest risk with 2-strokes is a lean running condition, which you probably don't have if you're blowing smoke. So give it some time to burn off.
I agree with old CB here. I am by no means an expert rebuilder, but I just finished putting together an 044 I did a full rebuild on a few days ago. I used assembly oil on all of the bearings, as they were brand new, and I didn't want to run them dry on start up. With a fully rebuilt carb adjusted to factory specs the saw was hard to start at first, but once it fired, ran great. The assembly oil in the bearings heated up and found its way out of the muffler, some in smoke form, some in liquid. After a few minutes of run time it cleaned right up. I took off the muffler, wiped everything down, and started a day later. No excess smoke, oil out of the muffler, etc. If you oiled your bearings on assembly this could be what you are seeing, and I don't think its anything to worry about.
 
a. palmer jr.

a. palmer jr.

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I don't know about you guys but I don't put a big bunch of oil or grease on the internals when rebuilding a saw, I coat the rings and a bit on the piston, a few drops on the crank, a bit on the wrist pin and that's about it. Never had a problem with it because when it starts it puts fuel in the engine which contains oil. I do make my fuel mixture a tad rich on a fresh rebuild though...
 
tkshrout

tkshrout

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Picking this back up- I rigged a pressure test for the carb using a blood pressure cuff. I pressured to 5 psi and it lost the equivalent of 1 psi in a little bit over a minute- is that acceptable, or does it indicate a carb rebuild?

Thanks for the answers to date!
 

J D

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It should hold around 10psi indefinitely... at some point above that it should "pop off" & loose all pressure. Make sure it's not your pump valve, lines or connections leaking. You can submerge the carb & look for bubbles to identify where it might be leaking from
 
tkshrout

tkshrout

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Ok, revisiting this.

I ordered an OEM rebuild kit for this zama carb. 11$ I think. When it arrived it was dated 2009. I went ahead and did the diaphragms and needle. Did not mess around with the shiny oval discs (welch plug??). Put it all back together. STILL lost pressure really slowly. The bubble comes out the hole in the cover plate very slowly (i think on the single screw side- but i honestly forget).

ANYWAYS... ran it, smoke cleared up, but now having a flooding issues while running. I have the H screw only like 1/4 turn out. It will idle, but when I rev/ put it in the cut it will flood and cut out. Did the same with the H screw about 1 and 1.5 full turns out. I thought turning it in would reduce the H and prevent the flooding. Any ideas if I can save this carb?

I guess I see a couple options:

1. The rebuild kit was no good OR the carb is shot. (should I try a cheap aftermarket rebuild kit? Any recommendations for an aftermarket carb? This model has no primer)
2. I have my understanding of the H screw backwards and turning it further in is causing the flooding. Should I turn it out? (by out I mean counterclockwise)

Thanks everyone!
 
a. palmer jr.

a. palmer jr.

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Those H and L screws will richen the carburetor if you turn them counter-clockwise. Start at about 1 1/4 turns out from lightly seated and see if that helps. You might end up having to buy a replacement carburetor, assuming you rebuilt the original correctly and it still didn't work..
 

J D

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Might just need to clean the sealing surfaces or tighten up the screw a little.
Did you set the metering lever?
Did you blow it out with compressed air?
I'd do some research before you attempt any more tuning... Madsen's has a good tutorial and @Vintage Engine Repairs did a good video recently.
Something is wrong if you have the screws much different to the 1-1.5 turns out that's been previously discussed.
Have you pressure tested the crankcase yet?
 

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