Who's running scored pistons in their saws?

[jmssaws]

Ah, you have 3 decked or popped 372's blowing 190.

Little of both. I've done them both ways and they run bout the same. There all 3 from 180 to 190 I've never got one to 200 on my gauge. The strongest one with the very bad piston is actually a single ring 371xp

 

[wde_1978]

The funny thing is there is a lot of saws out there running fine that the owners don't even know have scored pistons !

It was the fault of AS that I became aware of my Dolmar PS-6400's piston & piston ring score marks, if I hadn't read about pulling a muffler to inspect a piston of a chainsaw I would never thought of checking my saw.

This was November last year:


My PS-6400 has seen quite some work since then, if I had to guess another 20-30 tanks through it.
I re-checked May this year.
The pictures are not as good so they don't really show the current condition of the piston & ring, but to the naked eye the score marks didn't increase:


This saw runs great, fires up normally and comes back to life upon restarts better then her big sister the PS-7900!

I will pull the jug & piston , clean both and definitely replace the ring - I am just trying/waiting to get the needed parts together.

 

[Big_Wood]

It was the fault of AS that I became aware of my Dolmar PS-6400's piston & piston ring score marks, if I hadn't read about pulling a muffler to inspect a piston of a chainsaw I would never thought of checking my saw.

This was November last year:
View attachment 443264 View attachment 443265 View attachment 443266

My PS-6400 has seen quite some work since then, if I had to guess another 20-30 tanks through it.
I re-checked May this year.
The pictures are not as good so they don't really show the current condition of the piston & ring, but to the naked eye the score marks didn't increase:
View attachment 443267 View attachment 443268 View attachment 443269

This saw runs great, fires up normally and comes back to life upon restarts better then her big sister the PS-7900!

I will pull the jug & piston , clean both and definitely replace the ring - I am just trying/waiting to get the needed parts together.

did you even clean it up back then? not many people will see what i mean by this post but a few full of **** no experience people on this site are really showing in my eyes. this is to do with past posts made by others not by you. when i joined i made some posts saying some scoring in certain places did not matter one bit and a certain few shut me down big time. i would even say flamed me heavily but this proves what i said. of course the people who said this just fix saws up and get no significant run time on any saw to even have rights to speak from experience. exactly what i suspected back when the posts were made. the certain few know who they are! LOL

 

[wde_1978]

did you even clean it up back then? not many people will see what i mean by this post but the full of **** no experience people on this site are really showing in my eyes. this is to do with past posts made by others not by you. when i joined i made some posts saying some scoring in certain places did not matter one bit and a certain few shut me down big time. i would even say flamed me heavily but this proves what i said. of course the people who said this just fix saws up and get no significant run time on any saw to even have rights to speak from experience. exactly what i suspected back when the posts were made.

Sorry @westcoaster90 , I didn't quite get Your post - maybe because I came out of a night shift from work so I am not up to speed.

I didn't say the score marks don't matter!
I realize they can cost me the top end and even worse - and it bothers me big time.
Back then I cleaned out the exhaust port from carbon deposits and since tuned the PS-6400 just a tad leaner, about 100-200 rpm higher as she was factory tuned slightly over 13k.
I am sourcing needed parts so I can pull the jug & piston to inspect and clean them thoroughly.
I am having trouble getting parts from the new-to-me Dolmar distributor, thus I sourced a Caber piston ring from Greece on eBay, as well as an AM piston kit from Germany in case I deem the piston too damaged to re-use it.
Two weeks ago I also cashed out about 180USD and got me a spare OEM PS-7900 P&C kit - just so I have one for whichever saw needs it first.
If the Dolmar distributor doesn't come through with what I need/want from them, I'll ask my friend in Germany that bought me my Iggesund Forest bar to buy me a couple of cylinder base gaskets and mail them to me just so I can finally go forward and pull the jug.

This whole "restructuring" Makita is doing to the Dolmar brand is causing irritating delays and communication stalls.
Up till 2014. I used to have ordered parts within 24-72 hours delivered to my doorstep (unless they weren't in stock) , now it's a wild goose hunt with them.

I kept using my PS-6400 because with my small Sachs-Dolmar 105 being out of order she became my "little" saw.
The PS-6400 also has significantly better fuel economics and she isn't as mean as the PS-7900 when limbing and cutting thin stuff (which I did a lot off this year).

 

[cgraham1]

I have one saw that is a PITA to start, but runs good once it's warm.... I was going to sell it, so I pulled the muffler, and sure as ****, it's scored. I don't want to sell it like that, so I'll probably re-ring it and run it like that. It's an autotune saw and the piston kit is pretty pricey. Or maybe Shane wants it!??? Lol

 

[Chainsaw Jim]

I will pull the jug & piston , clean both and definitely replace the ring - I am just trying/waiting to get the needed parts together.

Just clean it and reassemble if you need to clean it. The rings ain't broke, so no need to fix em.

 

[Chainsaw Jim]

This is exactly why I tell people I don't want to see the saw run when I buy a used saw that's been sitting for a whole offseason. I tell them I just want to pop the muffler off and pull the cord to listen for clanking. Usually there is still old or bad gas in them and firing them up like that isn't good. There can be a puddle of old solidified mix sitting in the bottom of the crankcase from being flooded that won't come loose until the saw is good and hot.

 

[Big_Wood]

I have one saw that is a PITA to start, but runs good once it's warm.... I was going to sell it, so I pulled the muffler, and sure as ****, it's scored. I don't want to sell it like that, so I'll probably re-ring it and run it like that. It's an autotune saw and the piston kit is pretty pricey. Or maybe Shane wants it!??? Lol

PM sent! LOL

 

[Big_Wood]

Sorry @westcoaster90 , I didn't quite get Your post - maybe because I came out of a night shift from work so I am not up to speed.

I didn't say the score marks don't matter!
I realize they can cost me the top end and even worse - and it bothers me big time.
Back then I cleaned out the exhaust port from carbon deposits and since tuned the PS-6400 just a tad leaner, about 100-200 rpm higher as she was factory tuned slightly over 13k.
I am sourcing needed parts so I can pull the jug & piston to inspect and clean them thoroughly.
I am having trouble getting parts from the new-to-me Dolmar distributor, thus I sourced a Caber piston ring from Greece on eBay, as well as an AM piston kit from Germany in case I deem the piston too damaged to re-use it.
Two weeks ago I also cashed out about 180USD and got me a spare OEM PS-7900 P&C kit - just so I have one for whichever saw needs it first.
If the Dolmar distributor doesn't come through with what I need/want from them, I'll ask my friend in Germany that bought me my Iggesund Forest bar to buy me a couple of cylinder base gaskets and mail them to me just so I can finally go forward and pull the jug.

This whole "restructuring" Makita is doing to the Dolmar brand is causing irritating delays and communication stalls.
Up till 2014. I used to have ordered parts within 24-72 hours delivered to my doorstep (unless they weren't in stock) , now it's a wild goose hunt with them.

I kept using my PS-6400 because with my small Sachs-Dolmar 105 being out of order she became my "little" saw.
The PS-6400 also has significantly better fuel economics and she isn't as mean as the PS-7900 when limbing and cutting thin stuff (which I did a lot off this year).

of course i did not say it was ideal or that it didn't matter but there are alot of scoring in certain places that will smooth out on there own like yours did. usually carbon smearing but yours definitely looks to be more then that. i had a husky 55 i really didn't care about. got it free running scored and i ran it like that for 3-4 years. ended up giving it to my borther inlaw and he still runs it. scored alot worse then yous too.

 

[rmh3481]

Good thread Josh.

Check the ring lands good. How about scored cylinders how many are running them?

I recently sent an echo 8000 piston to Red Barn, and he had them made so there is an aftermarket option for that one now. They also had a couple of the older larger poulan pistons made too.

 

[Deleted member 83629]

i usually hone lightly scored cylinders to reuse them but if the scoring is bad i just toss them to find another cylinder
reusing a badly scored jug will screw up rings and blow by will be a problem.

 

[wde_1978]

Just clean it and reassemble if you need to clean it. The rings ain't broke, so no need to fix em.

The ring is stuck and damaged - thus it most likely doesn't do its intended job as efficiently as it should and cause more blow by then necessary.
The ring will get replaced as it will probably snap anyhow when I try to get it out of the groove.

 

[Chainsaw Jim]

The ring is stuck and damaged - thus it most likely doesn't do its intended job as efficiently as it should and cause more blow by then necessary.
The ring will get replaced as it will probably snap anyhow when I try to get it out of the groove.

View attachment 443388

I thought it might just be a rub mark and not a groove.

 

[Grits & Gravy]

I've got a 2101 with a cylinder that is vertically scored quite heinously... Been that way for years, I tore it down and stuck a new episan piston in it and it runs strong and blows 170lbs unmolested except for the gasket delete.

Good 2101 cylinders are getting harder to find these days, I'm gonna get all the good out of this one till i find a good replacement that I don't have to donate a kidney to buy.

 

[Chainsaw Jim]

This thread is going to totally fu*# the junk cylinder market all up.

 

[Adirondackstihl]

044
Ran, though not great
Main bearing went.
Causing radial play and causing the counterweight to wear into the base.

 

[Adirondackstihl]

Ran my 066 last winter (-20) rip cutting some frozen rock maple and white oak for a buddy.
Saw ran fine.
Some weeks later as I was preparing for our GTG, I pulled the muff cover for some muff modding only to find some carbon scoring. So rather than make it worse I decided to leave the 066 home and put her up so I could rebuild at a later date.
When I pulled the jug, I was shocked to see scoring on the lower portion of the jug below the intake. Then it wasn't until re-assembly when I noticed something a bit more shocking.

Intake


Exhaust carbon score


Intake skirt


Exhaust skirt


Plenty of oil




Here's what I found upon reassembly......


Factory defect big end bearing per STIHL warranty rep.
Although it had nothing to do with the scoring, I had to share that.
It's an early flat top 066 serial beginning with 134******

 

[stubnail67]

cool thread

 

[RedneckChainsawRepair]

I've got some badly scored ones out there still cutting firewood. 1 is in a 353 that was a test bed saw just to show they dont have to be perfect like folks think.

Saw impresses me when it comes in for service how it runs and compression. Have 2 new piston kits on the shelf but no reason why yet.

This scored p is going on its 3rd year right now. There is another out there for 8 years now in a 60cc.

 

[briantutt]

I probably won't use this one.

I might use this one.

Brian