scored piston

[Mr_Brushcutter]

Hi

I managed to break my 346xp a few weeks ago which you can read about in the 346vs260 thread. Anyway with the help of the guys who sent me the workshop manual i've been able to take it apart and i've got some pics of the cylinder and piston.

They appear to be scored up quite badly, is there anyhope of restoring them using acid and emery paper? or are they well and truely gone? A compleat cylinder and piston will cost more than i payed for the saw over here how much are they in the states?

Took the pics on my Nikon D50 but it doesn't capture what is there too well, i'll try and get some pics with another camera as well



Thanks for any help

Andy

 

[Lakeside53]

they don't look all that bad... at least as "scored" goes!

Even the piston doesn't look all that bad. New rings though, but look carefully at the bore. If it has bad groves or scratches up in the compression zone, then it's toast. If not, then it will recover nicely. Get a hone, even a three pronged brake hone, and use a drill to power it in manner that makes a nice cross hatch. I prefer a ball hone, but..

 

[Mr_Brushcutter]

There is some scratches and the wearing off of the top coat of shiney stuff on the front of the piston. Basicly its in line with the exhasut port about 1/2" long.

So i guess its toast.

 

[jcapodan]

Dude, this exact thing happened to my 359. I wonder is Husky's are suseptibal to this sort of thing. Anyway, I bought a new piston and ring kit, and ball honed it. The compression came up a bit, but was still only 90 PSI (needs to be at least 100 to 125 to run decent. I ended up buying (today) a used 359. I guess I will use my old one as parts..... Your pics don't look as bad as mine.

 

[HiOctane]

From here,it seems that everything is OK for me.We still see clearly cross hatching and it doesnt seem scored.And strangely ,its intake side,usually the ex side is damaged first.

 

[Mr_Brushcutter]

Got some better shots of the wear on the pison upon better inspection (halogen light) there is wear on both sides intake and exaust.


Thats the exaust side


That one is intake side

So that is shot right? The clinder looks ok though, normally don't they both go?

 

[NWCS]

most of the time the cylinder is salvajable unless its actual scoring. most of the time the piston donates some alum to the cyl and looks like it. hone the cyl, go with an aftermarket piston or salvage yours. definatly get a new ring.
if the intake side is scored check your air filter and your fuel.

here is the exhaust side of an 044 BigBore piston out of a saw that a customer ran with a clogged filter. he ran it till the filter was so bad it wouldnt run anymore. you couldnt even tell there was a filter under the caked on dirt and junk. even this piston is still usable (but not the best way to go) with new rings.
http://www.nwchainsaw.com/044piston.jpg

 

[Dan Forsh]

Your piston doesn't look that bad at all. Deep scoring is the problem, yours only looks superficial. I take it that the pic of the cylinder is after you have had a go at it?? If not, someone already has done work on it.
Dan

The only thing I would comment on, after looking at it again, the piston wall looks fine, but what caused the dings in the top face, if I'm seeing what I think I'm seeing

 

[Lakeside53]

Dude, this exact thing happened to my 359. I wonder is Husky's are suseptibal to this sort of thing. Anyway, I bought a new piston and ring kit, and ball honed it. The compression came up a bit, but was still only 90 PSI (needs to be at least 100 to 125 to run decent. I ended up buying (today) a used 359. I guess I will use my old one as parts..... Your pics don't look as bad as mine.

You need a different compression tester... your reading to way too low. At 100-125 they will not even start. Do a search about this on AS. The type you need has a schrader valve right at the tip where it screws into the plug hole.

Decent is 145-155. Great is 165 to 175. Beyond that, well... someone has been messin' with the saw:hmm3grin2orange:

 

[Mr_Brushcutter]

Your piston doesn't look that bad at all. Deep scoring is the problem, yours only looks superficial. I take it that the pic of the cylinder is after you have had a go at it?? If not, someone already has done work on it.
Dan

The only thing I would comment on, after looking at it again, the piston wall looks fine, but what caused the dings in the top face, if I'm seeing what I think I'm seeing

Nope thats the cylinder as i got it. I picked the saw up for 200 quid second hand, it ran really well at first then it ran lean and ended up fubar'd.

Hows the best way to go about restoring the piston? Where can i get the right hone or even an after market piston in the UK.

 

[Marky Mark]

Do a search there were 3 members who all gave there input on this. Close to a year ago this was a hot topic. Maybe it's under Gypo's 372 mod post.

 

[Four Paws]

Doctor doctor

Well, I picked up this 757 parts saw that had a scored piston. And, toasted it is...as you can see from the pictures...I got it apart today.

First, what is your take on the cylinder? It appears to have lots of aluminum depostited on it from the melted piston - can't tell if there is any significant scoring on the cylinder walls, through the nikasil.

Second, where can I buy a small ball hone for this? It has a 51mm bore, and if the hone is cheap enough, I will gladly buy one. If any of you guys want to be so kind as to let me borrow your hone (I will pay round trip shipping and guarantee to return it in top shape) or would take my cylinder and hone it for me (I would also pay round trip shipping and buy you a Twelver of your favorite beverage for your time) please let me know!

Thanks, Josh

 

[NWCS]

Josh: sent you a PM

 

[oldsaw]

Hi

I managed to break my 346xp a few weeks ago which you can read about in the 346vs260 thread. Anyway with the help of the guys who sent me the workshop manual i've been able to take it apart and i've got some pics of the cylinder and piston.

They appear to be scored up quite badly, is there anyhope of restoring them using acid and emery paper? or are they well and truely gone? A compleat cylinder and piston will cost more than i payed for the saw over here how much are they in the states?

Took the pics on my Nikon D50 but it doesn't capture what is there too well, i'll try and get some pics with another camera as well



Thanks for any help

Andy

Andy, I'm just not seeing it. You have some minor scuffing, not scoring. I'm going with the other guys, replace the ring, if your cylinder isn't rough to the touch, or you don't have any rough spots on the edge of the port, I don't think you really have a problem. Fix what needs fixing, and go cut some wood.

Mark