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Husqvarna 545 clearing saw - Autotune question?

Started by gwat, July 03, 2022, 02:28:30 PM

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gwat

I have a Husqvarna 545FX clearing saw.  Has been a stellar saw for the three years I've had it.
We are currently into a brushing project, running 50 hours/week.  

Yesterday I started it up and out of the blue the blade is spinning at idle.  The previous day it had been running completely fine.  

I let it idle for a few minutes, thinking the Autotune needed to sort it self out, but that did not resolve the issue.  I also took a look into the clutch, thinking something might be amiss in there but it appears all good aside from some pitting on the edge of the shoes (see pic below....is this normal?)

Seems like a high idle to me although I don't have an RPM meter to confirm this.
I let it idle for a few minutes then held the throttle wide open for 30 seconds (I believe this is the Autotune calibration procedure?) but it made no change. 

Any ideas or help would be greatly appreciated, I don't want to keep working this saw with the constantly spinning blade.




 





SwampDonkey

Check your throttle cable path from the top of the gas tank to inside the saw head case. On the 555, it is notorious for getting pulled out a bit by uncut brush intertwining around the handle bar and cable, that pulls on it. So that it now acts like you have your finger on the trigger. They don't clamp the cable down good. It's just in a sleeve groove. The Stihl clearing saws have a cable clamp that stops that foolishness.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

rusticretreater

Anytime a saw is acting up is a good time to check for proper mechanical operation.  If things are hung up, it simply looks to the autotune that you are holding the throttle open.

You can check on youtube and online for vids on autotune. I believe the procedure is to start the saw and let it idle for a full three minutes then run the saw full blast while cutting in some wood.  This gives it the load levels on the engine it needs to determine the fuel ratios to run.
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gwat

Thanks for that Swampdonkey. Throttle cable looks good, there is actually a bit of slack in the cable going to the carb and free play at the trigger.

I've had the exact opposite experience to you regarding the throttle cables!  This Husky throttle cable is solid, but we also run FS460C and they are always revving up when brush catches the cable loop. I can get the 460 to WOT by moving the cable housing around!  Sketchy.  This, and the exhaust port constantly getting clogged with carbon (even after tearing out the screen) are the only gripes I have with the 460.

gwat

Rusticretreater... ya I tried that procedure but it had no affect.

With brushsaws you can't really hold the blade in a cut for 30 seconds like you can with a chainsaw ...manual says to hold the blade in the air for 30 seconds at WOT.


gwat

Thinking more about this (and running a FS460 in the meantime) I'm wondering if this is unrelated to the autotune (as I believe idle RPMs are normal) but related to the clutch. 
Possibly stretched clutch springs allowing the shoes to expand at idle. It is plausible...has anyone experienced this?

SwampDonkey

 :D :D I've got a Husq 555FX and brush catches the throttle cable and pulls it all the time. I've never yet seen a 460 or 560 do it they are actually clamped down not just run in a  sleeve groove, and I see both brands every day. Thus your saw revs up and not even touching the throttle. The handle bolts snap off all the time on it. If you take out the drive shaft, that means it is actually stripped out and you have to always replace the clutch drum or it will chew up the star shaped shaft in no time again. So I gave up on Husq clearing saws because I had to constantly fix the junk. Went back to my trusty Stihl 560's and never looked back. I work with 3 other guys that run Stihl 460's and never had a single cable problem. :D The 555FX is lighter than the FS560 and good power, but it's too light for what/how I want to cut, too much down time. The FS560 is the most rugged saw out there for a clearing saw.

The screen on some saws were too fine, I've bought new screens and the mesh was more open. Also if your doing put put sawing and low RPM's you get more carbon. I was cutting plantation that was hardly considered cutting, very low rpms, snip here and there, carbon up in a week. In natural for weeks with higher RPM and never see it. This is true for both models because I seen guys on Husq have the same issue. Some guys just pull them.

Never had a clutch that did that on any clearing saw. When they go out, you've got no spin at all.

Some guys trash their saws every year or two, some guys look after them and they get 7-9 years, like mine. My Husq 555FX is a backup saw and works in good order. I just can't rely on it working a full week without being broke. ;)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

gwat

Well hot *DanG....finally had a day to dig into this and it turned out to be a broken clutch spring.  Replacing the springs was very simple and the 545 is now back in action!

Next up is getting to the bottom of why one of my 372s is running lean...

SwampDonkey

That'll do it for sure. :D But, I've never yet seen a broken clutch that would spin a blade. In fact most times I would suspect a broken or stripped out shaft when the blade don't spin and half the time it's the clutch instead.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

celliott

I was going to suggest broken clutch springs but you got it solved. A telltale sign of a broke clutch spring on a chainsaw (and a clearing saw would make sense too) is if the chain or blade rotates as you pull the engine over.
Your clutch shoes and drum may be worn too much and a new spring might not last long. Could be a new clutch and drum in the future.
Chris Elliott

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SwampDonkey

I'd replace the whole clutch as well. My experience on those drums for a Husq 555 is if the shaft is chewed up, the drum itself will be chewed up enough where the shaft comes in that if you just replace the shaft, the shaft will be gone again real soon. They have a star shaped shaft end. Never seen a 545 end.  So the drum and shaft both need replaced. I know guys that experienced this the hard way, and told me about it. But I still had to learn it the hard way to. :D A square shaft end would break off and not strip out, Stihl 560's are square shaft ends. I've only broke a couple in 25 years on a  Stihl 550 or 560. I took out 3 Husq 555 shafts in a year.

On two brands of clearing saws I've ran, if the clutch is gone, there is no spin at all. But like you say about the springs instead, just the opposite happens apparently.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

rusticretreater

Oh definitely replace the mating surfaces if you want to maintain full contact.  Things wear, and wear funny.  If they are already worn funny, they will wear even more quickly with results that won't be funny.
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gwat

Rusticretreater, you nailed it. Got less than four days on the new clutch springs and blew one again.  
I replaced the clutch and drum, hoping this is the final solution!

Spike60

@SwampDonkey , what do you do to the mufflers when they get all carboned up?

We usually set them outside on a piece of metal, light them up with a the propane torch and let the burn themselves out. Works just about every time. We run into this with landscapers that take off the guard and run line the diameter of a pizza pie. You can get away with it on certain trimmers with the "hi torque" gear boxes, but on most trimmers the RPM's will drop 600-700 for each additional inch of line. Granted I'm talking about the 25cc opposite end of the trimmer line up than you are using, but low RPM's will do this on any size trimmer. Especially those with CAT mufflers. 
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SwampDonkey

@Spike60 All I do is use a wire brush and clean it off. I have only needed to clean it a couple times this year when in real light plantation, running low RPM's. I looked at it the other day and still clean as a whistle because I'm in thick hardwood now. Mostly birch trees with some pin cherry to cut out. So the saw is running at the top end. And pin cherry is a lot harder than birch wood when green. Run a clearing saw in either and I bet you can tell the difference. Not a lot of water in pin cherry wood. ;D
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

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