Stihl FS44 - WOT rough

[vizette]

I've got an FS44 that I'm trying to get running clean again (obtained with a bunch of other equipment). I've got it idling OK, and starts to spin up OK, but at WOT it four strokes and spits gas out the carb.

If I turn in both needles all the way, it almost clears up, but of course won't idle like that. I've had the carb apart about 632 times trying to figure out what's going on. Went through it with a carb kit, so new diaphragm, metering needle, gaskets, etc. Tried lowering the metering lever with no difference - originally it was even with the body.

It does have a stainless reed valve behind the carb, thought that might be an issue, but that seems OK - I did flip it over to close up the gap a bit, but no difference. Seems to be smooth-ish part throttle.

Seems like a difficult model carb to find (WT-492A) so I'm trying to decide if I should jump on one on ebay right now for $25... Would hate to get that and find out it's some other issue, but everything else seems OK with this thing.
Also, if I drain the gas and run it high enough that it four strokes, it clears out and runs like an animal for a hot second before the fuel finally runs out. Again, makes me think carb, just not sure what else I could do to clear this up with the existing carb.

Pics of meter lever height and seat attached. Hard to make out the height in that pic, but it's level with the body (not the surrounding ridge).

Suggestions appreciated!

-Rich

 

[HarleyT]

Looking at the closeup of the carb with the needle out, the seat-area looks boogered up.

 

[vizette]

Looking at the closeup of the carb with the needle out, the seat-area looks boogered up.

Yeah I didn't notice that until I zoomed in on that picture... Think that can be saved? Or is that a goner?

 

[HarleyT]

I doubt it. But I am not close to the subject.

If the seat is damaged, and it is not an optical thing, it is a goner.

 

[vizette]

Got a better shot of the seat - looks good to the naked eye, but if you zoom in, it's a bit rough looking. Time to get on ebay!

-Rich

 

[vizette]

I'm really starting to hate this thing, may go on ebay as parts...

NOS Stihl carb - no change. Might be marginally better at WOT, but still spitting gas and running rough. Will check the reed valve again.

I guess it could be blow-by? Didn't see anything alarming when I took the muffler off, but that doesn't mean she's not just worn out.

Unless someone else has suggestions, probably sell her off as-is and be done with the grief!

-Rich

 

[psuiewalsh]

You pull the spark screen out of the muffler?

 

[vizette]

I did check that - everything looks good on the exhaust side and it's blowing out with pretty decent force. I think I found the issue though - I pulled the reed again to see if I could get it to seat better, as it was standing off just a tiny bit. I noticed while I had it out that the piston skirt was pretty nasty looking (almost black)... I'm guessing it's just wear, and there is a bunch of blow by at high speed, and that's the source of my woes.

I almost got it to run nicely at part throttle the other day. Smoothed out really nicely, but still can't get a decent tune on it. WOT is still rough unless I run both needles in, which of course won't idle or rev worth a d**n.

Anyway, I got a used motor on the way from ebay and debating just swapping the jug and piston so I don't have to take the whole thing apart. Will see how ambitious I feel when I get to it. With my luck with this thing, the crank seals would start leaking if I did that. I want to just part it out because I'm so irritated with it, but I can't let it beat me. I think I have a "problem"... LOL

Thanks for the follow up!

-Rich