Stihl 044 what did i do wrong? EDIT: I think It's Fixed

[lone wolf]

About $220 sadly

Get one on here used but working.

 

[Indy Red]

Get one on here used but working.

If I do not get anywhere with it will give you a look, sadly parts in the UK are eyewatering

 

[pioneerguy600]

If the metering needle valve had varnish on it, the coating you say was peeling off then the small drillings/passages that deliver fuel to the carb throat may be clogged up also, cleaning them out is also needed as part of a rebuild. Actually just last week I had a carb to rebuild off a MS440, it had multiple problems, 2 of the idle drillings were totally clogged and the 3rd partially. It has a leaking Welsh plug and a bad leaking nozzle check valve.

 

[Mad Professor]

Just checked the can i used and it was easy start, always thought them and carb cleaner were the same thing

Starting fluid is mostly hydrocarbons, alcohols and ether. Not too bad on rubber/plastics.

 

[Indy Red]

Does the new needle valve have the soft Viton tip on it? A new check valve would be a good choice but all the fuel passages should be cleaned out using jet drills to restore them to new condition, all Welsh plugs checked for leaking, they must be airtight, check that the L and H speed screws are tight fitting in their threads and that the tips are not damaged, post a good clear pic of those tips if you can. Many of the carb kits these days are not quite right as replacements for older carbs, the metering diaphragms do not always function the same as older carbs metering diaphragms did, the center button on the metal weight disc can be off in size and construction, just throwing a carb rebuild kit into a carb can render it useless. I have many carbs shipped to me for full rebuilds after previous owners installed a new kit and made the carb worse rather than better. If you decide to punch the high speed check valve out of the carb body remember to back the adjusting needles out, better to remove them than bend the tips. A rich running carb causes wet and blackened cylinders/pistons but that seldom causes wear of the cylinder, can cause carbon deposits on the piston crown and in the exhaust port. If that carbon breaks loose and jambs between the piston and cylinder that can cause carbon scoring marks, more so on the sides of the piston but usually does not score the hard plating on the cylinder walls. Running lean causes much more damage as less oil causes more friction that can melt the softer aluminum piston, that melted aluminum sticks to the cylinder all we call transfer.

So here are the H/L screws, they seem to be in good condition.
I will have to replace the check valve and If I mess it up, a used oem or something will my next step, one problem though, have no idea what a check valve is and how to get it out, I take it is one of those brass fittings or is it under that silver cap?

 

[pioneerguy600]

So here are the H/L screws, they seem to be in good condition.
I will have to replace the check valve and If I mess it up, a used oem or something will my next step, one problem though, have no idea what a check valve is and how to get it out, I take it is one of those brass fittings or is it under that silver cap?

Look in the carb throat, just inside the choke plate you will see a brass colored cylinder looking tube sticking out of the carb body just a bit smaller than a 22 caliber shell casing. That is the check nozzle, you can carefully punch it out into the carb throat. I made a special punch that has a bit of taper to the punch end instead of being perfectly flat on the end. I center punch the end on the inside of the carb and then center the bigger punch to that divot, it prevents a regular flat end punch from wandering over and scoring the carb body during the drive out of the nozzle. Most just whack them out with a flat punch and hammer but my machinist background will not allow me to damage anything I work on from carelessness. That silver cap is a Welsh plug, you find the idle passages under that if removed. Your H&L screws are in good shape, the ends are not bent or broken off where they enter the carb body passages. Do they fit the threaded portion of the carb body solidly as in no wobbling about?

 

[Indy Red]

Look in the carb throat, just inside the choke plate you will see a brass colored cylinder looking tube sticking out of the carb body just a bit smaller than a 22 caliber shell casing. That is the check nozzle, you can carefully punch it out into the carb throat. I made a special punch that has a bit of taper to the punch end instead of being perfectly flat on the end. I center punch the end on the inside of the carb and then center the bigger punch to that divot, it prevents a regular flat end punch from wandering over and scoring the carb body during the drive out of the nozzle. Most just whack them out with a flat punch and hammer but my machinist background will not allow me to damage anything I work on from carelessness. That silver cap is a Welsh plug, you find the idle passages under that if removed. Your H&L screws are in good shape, the ends are not bent or broken off where they enter the carb body passages. Do they fit the threaded portion of the carb body solidly as in no wobbling about?

Gotcha, So I punch down the one to the right of the Welsh cap, what is the one above the Welsh cap, Is that also a check valve?

No movement in the pins at all, Thanks for the advice you and the other forum members are giving me, It is very much appreciated

 

[pioneerguy600]

Gotcha, So I punch down the one to the right of the Welsh cap, what is the one above the Welsh cap, Is that also a check valve?

No movement in the pins at all, Thanks for the advice you and the other forum members are giving me, It is very much appreciated

The one that is more centrially located, it will punch down into the carb throat, try not to score the walls of the well the brass nozzle locates in when punching it out.

 

[J D]

This video explains the principal well...

The check valve in a carburettor throat is constructed a bit differently but the disc that does the sealing can sometimes be successfully replaced using a piece punched out of a fuel pump diaphragm.
Google can provide you a bit of information here...

 

[Indy Red]

The one that is more centrially located, it will punch down into the carb throat, try not to score the walls of the well the brass nozzle locates in when punching it out.

Doubt this will help also, will try to adjust it but i imagine a new flap and shaft may be needed, shaft looks a bugger to get hold of though

 

[Mad Professor]

So here are the H/L screws, they seem to be in good condition.
I will have to replace the check valve and If I mess it up, a used oem or something will my next step, one problem though, have no idea what a check valve is and how to get it out, I take it is one of those brass fittings or is it under that silver cap?

I think it was a Walbro?

Here is some good reading. Keep them for reference

 

[stihltech]

Maybe I missed it, but where is the inlet lever height set? You pressure and
vacuum tested the motor twice. Good.
Did you pressure test the carburetor with the metering diaphragm on and off? Does the center of the old and new diaphragm match? You did reinstall the high speed jet?
As far as the high speed nozzle jet, that usually shows as the saw leaning out at idle due to the valve not closing. All that fuel you are seeing at the muffler is not a usual symptom.
A place to start.

 

[Indy Red]

Maybe I missed it, but where is the inlet lever height set? You pressure and
vacuum tested the motor twice. Good.
Did you pressure test the carburetor with the metering diaphragm on and off? Does the center of the old and new diaphragm match? You did reinstall the high speed jet?
As far as the high speed nozzle jet, that usually shows as the saw leaning out at idle due to the valve not closing. All that fuel you are seeing at the muffler is not a usual symptom.
A place to start.

Inlet lever was set level with the carb body using the walbro setting tool (without the gasket on)
Pressure tested with and without the metering diaphragm on and all was ok, if you touched the lever fuel would spurt out so needle is working well.
High speed jet? I have not removed anything yet, which one is that on the carb, is that the one with the check valve on the end next to the welsh plug?
Only thing I have wondered is that all the holes have a brass jet or fitting in them bar one, is that meant to be empty?

I have put the carb back together using all the old parts that it came with, would start and die immediately and noticed the fuel hose was spilt where it connected to the filter, replaced with the new one and started up fine, though I could not test it due to time of night so will test in the morning.

 

[SteveSr]

Doubt this will help also, will try to adjust it but i imagine a new flap and shaft may be needed, shaft looks a bugger to get hold of though

Somebody boogered that carb up good! The problem that you now have is WAAAAY too much fuel. So much that its washing all of the oil off the cylinder walls and causing your new wear/scoring. I am surprised that it even runs like this.

The last person who ATTEMPTED to rebuild it used the WRONG kit/parts. The give-away is the needle tip. They used the wrong one which was too long and then tried to make it work by cutting the tip off of it. BTW, the carb inlet pressure test MUST be done with the carb fully assembled. Testing it without the metering diaphragm, gasket, and cover is useless.

The icing on the cake is the screwed up throttle plate. They are generally beveled and made to go in only one way. I don't know whay anyone would try to remove the throttle plate unless your particular carb has an accelerator pump that is operated by the throttle level. If it does and that is screwed up you have more headaches.

 

[Indy Red]

Somebody boogered that carb up good! The problem that you now have is WAAAAY too much fuel. So much that its washing all of the oil off the cylinder walls and causing your new wear/scoring. I am surprised that it even runs like this.

The last person who ATTEMPTED to rebuild it used the WRONG kit/parts. The give-away is the needle tip. They used the wrong one which was too long and then tried to make it work by cutting the tip off of it. BTW, the carb inlet pressure test MUST be done with the carb fully assembled. Testing it without the metering diaphragm, gasket, and cover is useless.

The icing on the cake is the screwed up throttle plate. They are generally beveled and made to go in only one way. I don't know whay anyone would try to remove the throttle plate unless your particular carb has an accelerator pump that is operated by the throttle level. If it does and that is screwed up you have more headaches.

Thanks Steve for the info, The carb is a Walbro HD-15B and I have returned the carb to how it was when I picked it up bar the needle, so I can basically start again with it, I have ordered a new throttle plate and other jets etc etc and already have the K10-HD WALBRO CARB REPAIR KIT to put on it, the problem I have noticed is that the gaskets in the rebuild kit are much thinner than the top & bottom gaskets on the carb currently and I am not sure if they are meant to be thin or thick as im sure that could make a difference.

The carb holds pressure/vac when all assembled, I am hoping the new throttle plate is enough to sort that particular problem as I cannot find any shafts for sale in the UK, The saw was used by the Environment Agency to cut tree roots through the dirt with a carbide chain and Stihl made them a special clutch plate with a flap to remove the excess dirt, even though low hour the saw got hot and blued the crank so I have replaced that and the bearings.

 

[SteveSr]

Thanks Steve for the info, The carb is a Walbro HD-15B and I have returned the carb to how it was when I picked it up bar the needle, so I can basically start again with it, I have ordered a new throttle plate and other jets etc etc and already have the K10-HD WALBRO CARB REPAIR KIT to put on it, the problem I have noticed is that the gaskets in the rebuild kit are much thinner than the top & bottom gaskets on the carb currently and I am not sure if they are meant to be thin or thick as im sure that could make a difference.

Hopefully, the K10 kit came in a genuine Walbro bag. Different Walbro models had different size needles. I think that the needles were different between the K10 and K20 kits. Pay attention to gasket/diaphragm order as they are different on each side of the carb. The new gaskets in the genuine kit should be the right ones. Also make sure that you use the correct diaphragms as the kit contains different ones for different model carbs.

Once you have the correct needle installed you will need to set the lever height if usingthe new lever in the kit. The old one may or may not be correct if you choose to reuse it.

You should be able to check the main nozzle check valve with a short piece of hose as described in the walbro documentation. If you do decide to replace it you MUST remove the "H" jet screw or you will ruin it and likely the carb body as the screw extends into the main nozzle

At this point I wouldn't replace anything that hasn't been confirmed to be bad including the main nozzle and welch plug. Welch plugs are hard to properly re-seal i.e. the factory can't even guarantee it and they have special tooling. Just shoot carb cleaner in the "L" screw hole and look for flow from the idle and low speed drillings. If all are clear leave the existing welch plug alone. If not try opening each hole wiith a tag wire and repeat the carb cleaner.

Luis at Walbro always recommended pulling main nozzles from the metering side to prevent leaks around the new main nozzle. I usually drill, tap, and pull the old one from the metering side. Puller can be made with a suitable bolt, nut and sleeve to pull the old nozzle into.

...even though low hour the saw got hot and blued the crank so I have replaced that and the bearings.

Bluing on big/little ends may not be from overheating as if it got that hot the bearings would be gone. It is much more likely from heat treating (hardening) the bearing bores.

 

[Indy Red]

Ok so ordering some carb parts and being told there is an 8 week lead time (will find a different supplier if I can) I decided to buy a Chinese carb off Amazon, picked the one that had the best reviews, not that that means much nowadays and fitted it today and sadly It is doing pretty much the same thing.

Tune it one way and if you turn the saw clutch side up the chain spins fast and then comes back down after revving, tune that out and will idle pretty ok even when turned on its side but when it comes back down after Wot it will be a different idle or will randomly drop rpm and stall, still seems to be very rich as well with a very wet muffler exhaust.

I know this screams air leak but it has been pressure/vac tested hot, cold, turning the crank when under pressure/vac and it holds, I am really stuck with it, I will be putting a new piston/cylinder in when It's sorted (125 psi currently) but will not be doing that if i cannot get it running right for fear of it tearing it up.

Parts it's had: All oem

Crank
Bearings
Seals
Piston Rings
HD2 Air filter replaced HD1
Fuel line/filter
Impulse hose
Tank Vent

 

[lone wolf]

Ok so ordering some carb parts and being told there is an 8 week lead time (will find a different supplier if I can) I decided to buy a Chinese carb off Amazon, picked the one that had the best reviews, not that that means much nowadays and fitted it today and sadly It is doing pretty much the same thing.

Tune it one way and if you turn the saw clutch side up the chain spins fast and then comes back down after revving, tune that out and will idle pretty ok even when turned on its side but when it comes back down after Wot it will be a different idle or will randomly drop rpm and stall, still seems to be very rich as well with a very wet muffler exhaust.

I know this screams air leak but it has been pressure/vac tested hot, cold, turning the crank when under pressure/vac and it holds, I am really stuck with it, I will be putting a new piston/cylinder in when It's sorted (125 psi currently) but will not be doing that if i cannot get it running right for fear of it tearing it up.

Parts it's had: All oem

Crank
Bearings
Seals
Piston Rings
HD2 Air filter replaced HD1

It acts like a vac leak , but did you put a new fuel line, filter and vac line ?
If so and it still does this vac test again and wiggle the crank ends up and down.
With 125 PSI I dont know why you are beating your head against a wall to get it running right!
Also you could try pulling-wiggling back and forth on the metal top handle while it's idling normal in the upright position and see if the idle changes indicating a bad impulse line or more likely an intake boot.
As far as worrying about it self-destructing again, it won't as long as you have replaced all the rubber parts Seals, Fuel line and impulse line then passes a vac - pressure test I do those very carefully and wont allow the slightest leak,you will be good to go. dont use knock off parts.

 

[Indy Red]

It acts like a vac leak , but did you put a new fuel line, filter and vac line ?
If so and it still does this vac test again and wiggle the crank ends up and down.
With 125 PSI I dont know why you are beating your head against a wall to get it running right!
Also you could try pulling-wiggling back and forth on the metal top handle while it's idling normal in the upright position and see if the idle changes indicating a bad impulse line.

Sorry forgot to include those bits as replaced, New fuel line/filter, new impulse hose. The reason why i wanted to get it right before replacing the piston/cylinder was because after the new rings it did score the cylinder a little (it was spotless before the new rings but) I need to know if it was the carb leaning out or the cylinder was just worn out and maybe had high spots that the new rings found.

The new rings had a ring gap of .012" so the cylinder was nearing end of life anyway.

 

[lone wolf]

Sorry forgot to include those bits as replaced, New fuel line/filter, new impulse hose. The reason why i wanted to get it right before replacing the piston/cylinder was because after the new rings it did score the cylinder a little (it was spotless before the new rings but) I need to know if it was the carb leaning out or the cylinder was just worn out and maybe had high spots that the new rings found.

The new rings had a ring gap of .012" so the cylinder was nearing end of life anyway.

Wiggle the handle while idling and see if the intake boot leaks. Working with 125 psi is frustrating, abandon that ! You did pull the saw over till the needle stopped rising, right?