Scored Piston - Jonsered 2258

[CristiRo]

After cutting some firewood, I decided to take off the muffler to see the P&C...
Wow...wasn't prepared for that...the piston is scored half way down the piston, on a width of about 5mm.
I'm using Sthil HP Ultra. Used this Ultra oil for 4L of gas with 40:1(25ml/1L) ratio. Before that the saw was run with LS+ from Husqvarna 33:1(30ml/1L).
Friday, I decided to try out the HP ULTRA in a ratio of 47:1(21ml/1L).
What could be the cause?! Build up of carbon in time has now come loose and scored the piston? Also, the cylinder is scored from the roof of the exhaust port up the cylinder wall.
Should I buy a new piston and ring?
What happened there...?

 

[sunfish]

I don't like HP Ultra, but I doubt it caused this. Might check for air leak.

 

[CristiRo]

It's the best oil I can find in my area.
Can I run the saw like this after I checked for leaks?

 

[blsnelling]

It's the best oil I can find in my area.
Can I run the saw like this after I checked for leaks?

The saw is injured. It's not going to get better on it's own. It looks to me like that saw has been run lean.

 

[CristiRo]

It's the first run after more muffler mod, probably I should have put more oil into the mix.
I'll try to see how it runs with more oil into the mix, not pushing the saw too much, and then buy a new piston and ring.
I don't have pics with the cylinder but, can be used?

 

[sunfish]

I wouldn't run it at all like it is. Just clean up the cylinder, new piston and check for air leak.
There has to be better oil where you live.

 

[CristiRo]

All i can find is: LS+ Husqvarna, Sthil HP, Sthil HP ULTRA, and i found an online shop that has MOTUL 800T 2 stroke.

 

[Totembear]

Red Armor!!!

 

[mountainlake]

It's the first run after more muffler mod, probably I should have put more oil into the mix.
I'll try to see how it runs with more oil into the mix, not pushing the saw too much, and then buy a new piston and ring.
I don't have pics with the cylinder but, can be used?

You need to adjust it richer not more oil. When saws scream the owner will be screaming shortly. Steve

 

[user 149785]

What does your air filter and intake plenum look like ? My local dealer had me look at and diag several of the red saws. The red saw comes with the nylon mesh filter and will not filter the fines correctly especially if your cutting hardwoods.if correctly mixed the hp ultra is a fine oil.my carver buddy ate two of these saws before we figured it out.the electronic saws keep compesating themselves even with a plugged air filter or contamination.

 

[mountainlake]

This has nothing to do with the air filter which would cause damage on the intake side, either to lean most likely or possibly a carbon deposit breaking loose but I see no heavy carbon buildup in the exhaust port. Tune it richer... Steve

 

[user 149785]

You can't tune an electronic saw it tunes itself !!! It compensates for whatever condition its operated. It doesn't know how rich you mixed the mix what air filter is in it or what type of wood its cutting ! All theorys on normal tuning go out the window with electronics.a new set of rules apply when running these saws.

 

[CR888]

Changing oil ratio's requires changing tune, more oil will lean out the air:fuel ratio. Just run Stihl HP oil and have saw tuned properly. But first this scoring needs attention, take this as a learning experience. Pressure/vac saw to check for air leaks. Hopefully rings, piston & shop Zen time will be all your out.

 

[user 149785]

Initial tune yes ! Operational conditions ? Think about it ? I have run 50:1 premium fuel on ported saws w/ no problems at all.even run hp oil on occasion mostly lucas.i mix 5 gallons at a time theres no way a muffler mod or even port work should effect this saw in such to scar the exhaust port.there's another factor involved.

 

[backhoelover]

The saw is injured. It's not going to get better on it's own. It looks to me like that saw has been run lean.

should he of hot retune the saw after the muffer mode.

 

[backhoelover]

need to hook up the computer and look at your fuel curves. and see if you have any codes. here is the fuel chart

 

[Jcubb]

you can easily fix that piston with some sanding work. Just sand out your marks and test fit the piston in the cylinder. As long as your piston to wall clearance is not too much you will be fine. I have 2 saws that I have repaired pistons on that looked significantly worse than that. If you are taking the cylinder off check the crank bearings. It is possible that the cage has broken a piece off and shot up into the cylinder causing that damage. I seriously doubt that the oil you are using caused that damage

 

[mountainlake]

Too me if its a autotune they are set up on the edge of running lean, don't be making these saws work hard in long cuts keep the RPM up to keep them from melting down. Steve

 

[user 149785]

My local dealer didn't even have me hook up to the diag tool.he told me to port it muffler mod it run a full tank of fuel through it at max load(. noodled oak for a full tank).mix the fuel correctly and run it.i haven't had one problem on any of my electronic saws.its either a factory defect or another equation.did you set the saw in under load ?

 

[blsnelling]

should he of hot retune the saw after the muffer mode.

Always!