Husqvarna 55 p/c problems

[LegDeLimber]

What caused those dings in the piston skirt.

Skirt looks bent on the intake side. Could be the light, but looks like the edge of wear/contact zone meanders a little above the dings at the bottom right of the skirt.
Then it kinda tracks over and swoops back up to that big ding on the left.

 

[BigDee]

What caused those dings in the piston skirt.

Good question. I forgot about those dings in the earlier pics.

 

[04_snopro]

Im pretty sure its just the way the flash hit it making it look that way. But as for the dings im not sure. Didnt find anything in the case that could have caused it. Im almost begining to think maybe it been like that since i got it and ive owned it for 7-8 years and have used it every year cutting about 18 truck loads of firewood per season. This is the first time ive had the muffler off and that was clean all the gunk out from under it that builds up ontop of the crank case under the muffler and thays when i glanced in at the piston and saw it. I did notice the gromit for the impulse pipe was split in two and i recall at one time the comp release valve stuck open and that would make sense to me that the piston is scored on that side but im no expert and im not setup to vacum/pressure test so i was just gonna do crank seals and all.

 

[LegDeLimber]

After staring a little more, It looks like a small ding on the, bottom center, of the exhaust side skirt also.
Probably not anything to sweat over.

The intake side kind of makes me think maybe someone had the cylinder off and then spun the crankshaft.
Perhaps they were trying to spin off the clutch (or flywheel nut)?

I would think that a close scrutiny of the wall thickness in and around the dented areas is warranted.
Look , inside & outside, for any signs of cracks or other weakening too.
-
But I'm just spouting about general stuff here.
Hopefully the guys who have handled and built this saw, will step in with some actual info!

 

[cedarshark]

Here are pics of a OEM 55 Closed port repaired piston:
Before:
After:
You will note this was done with a dremel tool on the lowest speed. I think you have found the source of your air leak with the split intake grommet in the cylinder. I see no way to repair it and the price($$7) is absurd but is available on flea bay. The plastic intake partition is available as well for about the same price. I would not re-use the original partition as chances are good the self threading carb screws will back out over time and cause another air leak. As well as these saws run...the intake is poorly designed and warrants special attention. Search for a thread by "rynasaur" titled Best Fix for a 55 Intake( or something like that). It will give you instructions on how to fix this problem permanently. Its a good fix...just did it.

 

[BigDee]

Cedarshark's piston work(nice work) is much more thorough than mine. I merely sanded to make sure there were no high spots pushed up by the scoring, to maintain as close a fit as possible. It doesn't look much smoother than Cedarshark's did at the start. I hope some piston-salvage experts will comment on what is best. Don

 

[cedarshark]

I was concerned about piston slap on a repaired piston. Guys a lot more experienced than I told me that that my OEM piston has ample support on the undamaged sections of the pistons (machine marks on the bottom of the skirt) to warrant repair. I have NOT tested the compression on this saw as it was just put back together yesterday. I will test and advise. I did pressure/vac test and found no leaks. These saws are seriously under rated and bashed due to the intake design, but they are very robust 50cc saws.
Mine is in very good shape and worth repair :

 

[04_snopro]

Cedarshark, thats a very nice looking 55 u have there and some fine looking handy work with the dremel. I love the saw and the best part is i payed 125 for it back when i got it. And ill definatly check out that link on repairing the intake. Thanks everyone for all the input on this. Ive definatly learned a little bit of useful knowledge espesialy about saving the piston.

 

[BigDee]

Thanks Cedarshark. It looks like a beauty. Nice pics tell a lot, yours and the OP's.

 

[cedarshark]

My saw compression tested at 110psi. Not good. A few drops of oil in spark plug hole and it retested at 140 psi. I will pull the decomp valve, plug it and retest this weekend but I don't like the initial results. 110 psi is just over what a saw requires to run, much less run well.

 

[MnSam]

Here are pics of a OEM 55 Closed port repaired piston:

That is actually a lot more than I would have removed, curious to see how that runs for you. Not saying it's wrong. If it works then it was right! That still shouldn't affect the compression. I wouldn't worry about compression too much until you run it a little bit. Then check it with the proper fuel mix coating the engine. I like these saws a lot, I have one needing put back together as well. My piston is border line IMO and have been trying to decide whether or not to go with the red barn one.

 

[MnSam]

I had to go look at mine again. I think it would be fine but I will probably clean a little more and use it. A clean cylinder is the key.

 

[BigDee]

My saw compression tested at 110psi. Not good. A few drops of oil in spark plug hole and it retested at 140 psi. I will pull the decomp valve, plug it and retest this weekend but I don't like the initial results. 110 psi is just over what a saw requires to run, much less run well.

Did you check the squish? Some are large, like almost .040.

 

[cedarshark]

Good point. I will do this when I plug the decomp valve.

 

[cedarshark]

Has anyone deleted the base gasket on this saw to improve compression ?

 

[MGoBlue]

Of course.

 

[MGoBlue]

I just searched and couldn't find pics to show squish measurement for the cp. W/ the op cyl it was .0335 without gasket.

 

[BigDee]

My reading of nearly .040 was without the gasket. I've had the bases milled down.

 

[muddstopper]

Here is a new closed port piston, http://www.hlsproparts.com/Husqvarna-55-55-Rancher-windowed-piston-kit-p/h31055-w.htm. I did try one of their closed port p/c kits and didnt like it. .080 squish. Saw would run, but very low powered. I set the kit back and they refunded my money. I also used one of their open port pistons and a used cyl on another rebuild. Kept the base gasket, squish was around .040 give or take a few million years. That saw runs well. I have also tried a few of those other china kits, and havent been really satisfied with the results. I found some nos and bought 3 kits. I have used one and saw runs just like a new one. I have a parts saw I am thinking about doing a complete rebuild on, if I can find another saw to get the covers off of.

 

[cedarshark]

I believe I may have created my compression problem. When I tore the saw down, I noted the OEM base gasket was the thinest I have ever seen. It tore coming off. I made a duplicate but did not have gasket paper that thin. I probably created excessive squish. I bet to get the squish down to .020(or close), it would take milling the base.