bikemike
loud pipes save lives
Also depends on the fuel and oil you use and how long the fuel has sat in the system.. a good carb can go bad at any given moment
346XP. "H" screw all the way in and only ~11,000 RPM, no load. Need some serious tuning advise!
- Thread starter rustyb
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I took the carb apart...well, partially. From what I could see, it seems super clean. I stripped the head of the screw holding the metering valve in though. Fu%&&K!!! How could I have possibly done that???!! It's stuck in really tight, obviously, but the metal seems overly soft too! Crap...
Bikemike - I use the highest octane gas I can find (91) and Stihl synthetic oil at 50:1.
Bikemike - I use the highest octane gas I can find (91) and Stihl synthetic oil at 50:1.
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Crappy on the screw. I think you're onto something with the carb. See the yellow varnish stuff under the brass plug in the picture? The crusty old gas that you can just pick off. There's probably more like it in other passages in the carb. I'd pull it completely apart and get some carb cleaner soaking in there. Take the high and low needle out too.
Normally I'd do this with the inlet needle out. If you need the saw soon you could try cleaning everything else and putting it back together. If it helps you've solved you're issue. If not you need a screw ordered. It's tricky but you could probably center drill it and use a small extractor. Do it after you get the new screw so you can see what your working with. Maybe even use a dremel to grind a slot in the head so you can try a flat screw driver first?
Did you use a number one Phillips on the screw? It's a 2. It looks like only the center is stripped. Enough left to get a 2 on it?
Thanks, guys!
Re the screw....I'm not sure on the size of driver. I just got a driver that seemed to fit and it wouldn't come out. I then tried my impact driver and that's when I really screwed it up. Pretty damned dumb. In my defense though...that thing is really stuck in there. Never experienced a screw stuck like that in a carb before.
Assuming there's more varnish inside the carb....would that cause the issue of it acting like it was running out of gas AND prevent it from getting past 11,000 RPM even though the HS screw was all the way in? In other words, could varnish cause both issues?
Re the screw....I'm not sure on the size of driver. I just got a driver that seemed to fit and it wouldn't come out. I then tried my impact driver and that's when I really screwed it up. Pretty damned dumb. In my defense though...that thing is really stuck in there. Never experienced a screw stuck like that in a carb before.
Assuming there's more varnish inside the carb....would that cause the issue of it acting like it was running out of gas AND prevent it from getting past 11,000 RPM even though the HS screw was all the way in? In other words, could varnish cause both issues?
It's possible. The side issue is sometimes a sign of an air leak. Bad seals. An air leak will make the saw scream with high rpms. It contradicts what you're seeing.
I run my saws dry for long term storage. A couple of years with the same gas stuck in the carb is bad news. My suggestion is to address the dirty carb and see if it changes your symptoms. I just did a 353 for my father in law. Carb looked like yours. I had it in my ultrasonic cleaner for quite a while. When I unscrewed the h needle I could see gunk on the inlet. Worth a look. A blockage there won't let the needle seat.
Have you tried tightening the screw to cracked it loose?
I think you have a really good saw that just needs a little tlc and not a lot of $$$$. Painful to have to deal with that screw.
I run my saws dry for long term storage. A couple of years with the same gas stuck in the carb is bad news. My suggestion is to address the dirty carb and see if it changes your symptoms. I just did a 353 for my father in law. Carb looked like yours. I had it in my ultrasonic cleaner for quite a while. When I unscrewed the h needle I could see gunk on the inlet. Worth a look. A blockage there won't let the needle seat.
Have you tried tightening the screw to cracked it loose?
I think you have a really good saw that just needs a little tlc and not a lot of $$$$. Painful to have to deal with that screw.
Can you get a flat screwdriver across the gap between those two nice looking grooves. I think i'm obsessed with getting that screw out! Lol
I'll add somthing useless cause I'm sure you tried this I have a new to me 346 I had very similar symptoms I fought this saw a couple weeks and almost pulled the carb ... Did you try to tune the saw with the top cover off? I had the exact same issue today I tried it again exact same thing acted like it was running out of gas lost power and no top end rpm .. What was actually happening was when I was tuning it through the top cover the screwdriver was binding ever so slightly making it seem like the high needle was "in" .... I took the cover off and it tuned right in wherever I wanted it you could adjust the low side no problem the high side would fool you . I had a damn fine mechanic that also tried to tune it in and couldn't get it right I just randomly had the cover off looking for issues is when I discovered the dang issue was in the screwdriver binding just slightly on the plastic making me think it was the limit of the screw
That's good, cause I need the help/encouragement/ideas! I'm not sure about getting a flat driver in there. All the parts are in my shed at the moment and I needed a break from it. I might try that tomorrow though. Thanks!Thanks for that thought! I actually did tune it with the cover off....only because I didn't want to mess with mounting my tach to the saw. I tuned it on the bench, tach wire connected to plug wire and tach fastened to the bench.
I found the exact thing with the 353! You really have to concentrate to get the screw driver lined up with the slots!
bikemike
loud pipes save lives
High octane don't always mean no ethanol but a carb kit is easy unless a screw screws with lol
If a flat will fit try about ten different flat screwdrivers to make sure you get a nice tight fit with the flat you'll only get one more shot at getting it out with the flat screwdriver tip which was a damn fine idea
Chris-PA
Where the Wild Things Are
That doesn't look like varnish to me - looks like sealant on the welch plug. The carb looks rather clean actually. I suspect it's a wild goose chase.
What has been done to the saw? Did you remove the limiters or did someone else, and if it was someone else are you sure what all was done?
Have you checked the metering lever height yet? That is a likely explanation of the issue, as is damaged A/V mounts or a boot given that it's been pinched and yanked on.
Last, it sounds like it has been lean at times in the past, so you should pull the muffler and check the piston. Low compression will make it hard to tune and lazy.
What has been done to the saw? Did you remove the limiters or did someone else, and if it was someone else are you sure what all was done?
Have you checked the metering lever height yet? That is a likely explanation of the issue, as is damaged A/V mounts or a boot given that it's been pinched and yanked on.
Last, it sounds like it has been lean at times in the past, so you should pull the muffler and check the piston. Low compression will make it hard to tune and lazy.
bikemike
loud pipes save lives
A thin wore down dremel cut off wheel will get a slot in it or a sharp center punch with the carb in a vice. My dremel skills would make me want to slot it like a poulan tuning needle
I've learned something new. Of all the carbs I've been in I've only seen that on one saw that sat for a long time.
Chris-PA
Where the Wild Things Are
Hey, you could be right, it's only a picture. The rest of it does look remarkably clean though. Sad to say, if I had to bet it would be that there are more serious issues than the carb.
I bought this saw new, then opened the muffler and removed the limiters. I did it myself.
I have not checked the metering lever height. How does one do that?
Re the boot: It's held to the cylinder via some goofy looking metal clamp that appears to require a special tool to remove. How do I remove the clamp so I can get the boot fully out to thoroughly inspect? I fumbled around with needle nosed pliers but stopped in fear of screwing up the clamp.
What's the clamp look like? 3 prongs at the end facing out? On those ones I pinch with needle nose or small pliers and start wiggling the boot until it pops off. Sometimes put some pressure on the cylinder end of the hose with the side of a flat screwdriver.
Derrick Sawyer
ArboristSite Guru
I would vote for buying a brand new carb if you don't have another one to test off a good running 346, I always like to have an extra good carb to make diagnosis easy on all my model saws, plus these 346xp carbs are like $30 shipped to your door, make sure the get the real oem zama and the proper one since they are different for the OE and NE due to primer bulb or not. Plug looks obviously rich, so when you cut on its side any of the fuel mix pooling at the bottom could make it even more rich. Also agree turning the H and L screws is easier with cover off (but more dangerous) since the screwdriver angle is not straight in, that said if you took the carb off, you should be able to confirm it was completely turned in. Also, when idleing the saw should die when the L is turned all in.
With carb off, a vacuum check would be good too, there is a universal flange that works. I also changed the clamp to a large stihl style screw clamp, and you could also use an extra plastic flange that the long carb screws go into since they are easy to overtighten.
good luck.
With carb off, a vacuum check would be good too, there is a universal flange that works. I also changed the clamp to a large stihl style screw clamp, and you could also use an extra plastic flange that the long carb screws go into since they are easy to overtighten.
good luck.
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