Husky 55

[bluthum]

 What's the compression supposed to be on a Husqvarna 55? I  have 2 both of which show 125# which I guess is  low? These are the only saws I have and I'm trying to plan for the future..

[wild262]

          It is low, but some saws run with 125lbs.  They certainly cannot be very strong, that's for sure.   I had some that wouldn't start at 120.  The Husky 55's are some of the easiest to work on to gain compression.  Now would be the time to rebuild them for the future, cause there only going to be more problematic, especially with starting.

[bluthum]

Thanks! Both start same as forever and run fine but I keep thinking they are a little weak tho it's hard to be subjective. One I bought new and the other I got for parts a few years back and ending up resurrecting.

I took the muffler off the 20 year old one and it it had a 1/4" wide streak of scoring on the piston centered on the exhaust port. The muffler gasket was toast and hence replaced but I've no idea what constitutes significant scoring.

Rebuilding is being considered. I haven't ever gone that far with wrenching but may give it a whirl.

Any further advice is appreciated.

[sawguy21]

wild262, what would you expect to see? 125 sounds reasonable to me, I would leave it alone unless it is giving problems. The 55 is a very stout farm/ranch saw, one of my favorites.

[wild262]

wild262, what would you expect to see? 125 sounds reasonable to me, I would leave it alone unless it is giving problems. The 55 is a very stout farm/ranch saw, one of my favorites.

If I see at least 130, I leave it alone.  Any lower, I just go ahead and rebuild.  There's a reason for it being low, or it would be there.  Yes there a strong saw, when they have normal compression.  I don't call 125lbs the norm.  A healthy saw is 140 & above as I see it.  

[wild262]

       You sure have one of the easiest models to start out on to redo.  That scoring your talking about no doubt adds to the low compression.  If possible before you tear one down, I would pressure/vac. test to see where any air leaks might be.  Those are built like the higher-end saws as regards to a magnesium case, and P/Cly.  Doing the work yourself can save you lots of money, and you will have a saw that will be miles ahead of any box store model.  Lots of videos on line to get you started, and its not hard at all on that model.  Parts are easy to find for it, and cheap.  I do recommend you re-place the plastic intake partition.  That part cracks with age and heat, and is responsible for burning a lot of them up.  Were all here to help you if you need any.  ;)

[wild262]

Bluthum.  Does your 55's have compression releases?  If not closing properly they will give you false readings.  Plug them and check again, then you will know for sure. 

[Allar]

Imo 125 psi is fine.
If it works, don't touch it.

[bluthum]

One has compression release., one not.  So one to check again. Are comp releases pipe thread or machine screw thread?

Both have had new bulkheads, carbs and impulse and manifold tubes in the last few years.

Could a bad muffler gasket cause lean running symptoms?  I can't pressure test the crankcase myself or at least how the shop manual shows.

 For some reason shop manual does not tell how to comp test or even give suggested cylinder compression. Maybe that's because your "mileage may vary"  as is suggested by the variety of opinion here.

Anyway thanks to all for input.

[limbwood]

125 is'nt bad at all. 80 is low then they wont idle very good ,i would leave them alone.

[dougand3]

I like 150+ in a Husky 55. I have one that is 180 PSI - really strong saw. Muffler gasket will not affect compression - if it leaks, the front of the saw is dirtier. Decomp threads are 10mm x 1.0 pitch - kinda rare size. IIRC, it's plug bolt thread length is only 9mm.

[wild262]

One has compression release., one not.  So one to check again. Are comp releases pipe thread or machine screw thread?

Both have had new bulkheads, carbs and impulse and manifold tubes in the last few years.

Could a bad muffler gasket cause lean running symptoms?  I can't pressure test the crankcase myself or at least how the shop manual shows.

For some reason shop manual does not tell how to comp test or even give suggested cylinder compression. Maybe that's because your "mileage may vary"  as is suggested by the variety of opinion here.

Anyway thanks to all for input.

Takes a pipe thread plug for the comp. release hole.             How does the saw run that's in question?  Does it surge at idle, or race to high rpms with no reason sometimes?   Does your chain continue to spin at idle?  These things may be an indication there may be an air leak.   I also see that I'm outgunned for saying 125 psi is to low.   I had assumed by your first post that you wanted to fix this for a good saw for future use, so I recommended you to rebuild.    My point 'to all" is,  if there is something going on with it to make it lose compression, why not investigate and find the problem now, before it causes further damage?  You did say one had some scoring.  To me, that's the one I would rebuild while having the other for use.  Opinions vary, but thats my reasoning for why I suggested it.  Any dealer with any smarts at all should be able to do a vac/pres. test without it costing you an arm & leg.  Manuals sometimes don't show you as they vary a lot from saw to saw.  The muffler problem should be an easy fix if you don't have a broken flange to hold the head of the bolt in place.  Not considered an air leak there, but you don't want to run it that way.    Even if we all disagree, our goal is to help you out.  Have a good one 8) 

[wild262]

I like 150+ in a Husky 55. I have one that is 180 PSI - really strong saw. Muffler gasket will not affect compression - if it leaks, the front of the saw is dirtier. Decomp threads are 10mm x 1.0 pitch - kinda rare size. IIRC, it's plug bolt thread length is only 9mm.

I totally agree.  I like to see at least 130.  Would rather run a 55cc then to have it cutting like a 40cc.  ;)

[bluthum]

Wild- I can see the merit of leave it alone and also fix it opinions given. Often what ever I do is wrong anyway. I am leaning toward the idea of fixing the one with the scored piston.

 What got me started on this was the one with the scored piston did not want to carb tune, the high side wouldn't say put. Since I put on a muffler gasket it seems to be running nice but I wonder the cause of the scoring. Seems like I remember reading some where that you can diagnose the cause of scoring by it's characteristics?  This one is narrow and right dead center in the exhaust port.  

In any event I think my next step is to try to get it leak tested locally.

Thanks again to everyone for the advice and opinions!

[wild262]

        If the carb. wouldn't stay adjusted, then it could cause scoring either way.  Too rich would cause carbon build up that could chip off and score the cylinder.   Too lean, could cause alum. transfer from your piston onto your cylinder.  Sounds like you got an air leak somewhere, and may or may not be the carb.  Another good reason to check for leaks now, then later.  You don't want to ruin any new replacement parts.  If this is the saw that has the comp. release, take it off and plug it.  Or if you have the shop to do a leak down test, to check it out.  I have seen these stick once in a while, especially if the saws been run rich with carbon build up.  If you do your own carb. adjusting, make sure your doing it correctly.   You don't want it rich in the cut.     Or, just forget all of the above, and just run as is.  You can put a lot of money in a old saw, esp. if you pay to have it done.  That's your call.