Husqvarna 550XP intermittent power mystery.

[Guest Gimlet]

3 hours ago, spudulike said:

Saws hanging on to their revs after snapping the throttle shut can be a sign of an air leak being present. Did the dealer give you the readout from the CST (customer service tool) test? The H&L carb settings from this document can often give an indication if there is an air leak.

No. They gave me nothing but the bill.

[Guest Gimlet]

18 hours ago, spudulike said:

Saws hanging on to their revs after snapping the throttle shut can be a sign of an air leak being present. Did the dealer give you the readout from the CST (customer service tool) test? The H&L carb settings from this document can often give an indication if there is an air leak.

It wasn't hanging before it went in, it was just stumbling and wouldn't rev. 

[spudulike]

On 23/02/2023 at 19:17, Gimlet said:

Still playing up after it came back from the dealers. Seemed to idle too high (although the chain wasn't going round) and the revs would hang for a second or two when the throttle was released.

Sorry, I was just going on your description above

[adw]

On 23/02/2023 at 19:17, Gimlet said:

Still playing up after it came back from the dealers. Seemed to idle too high (although the chain wasn't going round) and the revs would hang for a second or two when the throttle was released. Did the "secret screw" thing this afternoon and it seems to have cured it. Find out tomorrow when I get it fully warmed up. 

 

Fecking thing it is. I think I'm done with Hasqvarna. Even the their fuel/oil can is crap. dribbles and leaks. Next saw will be a Stihl.

A little late to say this but altering the " the secret screw " is not a good idea, it is set by the carb manufacturer and can upset the carburetion  completely.

[Guest Gimlet]

17 hours ago, adw said:

A little late to say this but altering the " the secret screw " is not a good idea, it is set by the carb manufacturer and can upset the carburetion  completely.

I backed it out a quarter of a turn, which seemed to be the consensus on-line. Have to say, it does seem to have helped. Tickover is more stable and there's less hang, though it doesn't snap back as smartly as it did before it started playing up. I could easily return it to factory. 

I think I need someone to do some better diagnostics on it.

[adw]

49 minutes ago, Gimlet said:

I backed it out a quarter of a turn, which seemed to be the consensus on-line. Have to say, it does seem to have helped. Tickover is more stable and there's less hang, though it doesn't snap back as smartly as it did before it started playing up. I could easily return it to factory. 

I think I need someone to do some better diagnostics on it.

I think you are right, the 550 mk 11 has been very reliable compared to the first generation, start with a pressure/ vac test to rule out any leaks followed by an assessment of the fuel system.

[Suffolk Dave]

Hi All

Bite late to this, over the years I ran 4 mk1 550, in warm weather all 4 did not run well ,if you run them you would have noticed how husqvarna tried to keep the heads cool by keep cut away at the top plastic casing on the side, the original was solid ,as time went on various bits cut away of the plastic casing to try to cool them,

Now the mk 11 that's a different machine no problems with them full of power run well

[Guest Gimlet]

On 24/02/2023 at 19:33, spudulike said:

Saws hanging on to their revs after snapping the throttle shut can be a sign of an air leak being present. Did the dealer give you the readout from the CST (customer service tool) test? The H&L carb settings from this document can often give an indication if there is an air leak.

You were right Spud. Sucking air through crankshaft oil seal behind flywheel. Took it back to the dealer Monday. Why they didn't find that the first time round I don't know. But they've sorted it and changed the seal on the other side as well for good measure, as they said that one usually goes first as it gets hardened from being doused in chain oil. And they put it through under warranty too so nothing to pay. 

Hopefully it'll behave itself now for a while.

Edited March 3, 2023 by Gimlet

[spudulike]

On 03/03/2023 at 21:04, Gimlet said:

You were right Spud. Sucking air through crankshaft oil seal behind flywheel. Took it back to the dealer Monday. Why they didn't find that the first time round I don't know. But they've sorted it and changed the seal on the other side as well for good measure, as they said that one usually goes first as it gets hardened from being doused in chain oil. And they put it through under warranty too so nothing to pay. 

Hopefully it'll behave itself now for a while.

Sorry, I missed your reply but am glad you sorted it. I have found the radial seals pushed in to the main bearings on the clutch side of the 346, 550 and 560 do have a tendency to start leaking after a few years.

Glad you got it sorted and you are happy now.

Thanks for letting us know.

[htb]

Steve, do 372 XT suffer from this as well as mine hangs onto its revs when coming off the throttle?