stihl ms 440 cylinder question

[floriceeel]

hi, I bought an ms 440 in january ,it is still available in russia and I was wondering what brand of cylinder are they using now.I'm asking you this question because recently I have seen a few very fine vertical scratches inside the cylinder through the plug hole but not on the piston.It hasn't got any problem with the compression ,it is the same as it was before but I am a bit worried.The saw has about 10 tanks through, a mild muffler mod and it has been tuned by the dealer after I did the MM at 13.5 k as the manufacturer says. I have cut only branches during the first 2 tanks.I use hp ultra oil at a ratio of 40:1.What should I expect in the future ? Thanks !

 

[cgraham1]

The saw has... a mild muffler mod and it has been tuned by the dealer after I did the MM at 13.5 k as the manufacturer says.

I didn't know that the manufacturer recommended a specific RPM to tune a 'modified' saw... the lines are probably just oil residue, as it's likely that your saw is tuned too rich with the muffler modded. It is always best to tune a saw by ear, and forget about the tach (and the "dealer" for that matter).

 

[floriceeel]

I didn't know that the manufacturer recommended a specific RPM to tune a 'modified' saw... the lines are probably just oil residue, as it's likely that your saw is tuned too rich with the muffler modded. It is always best to tune a saw by ear, and forget about the tach (and the "dealer" for that matter).

It's set to manufacturer specs.Not much of a mod ,just enlarged the muffler opening by 30℅ of its original size.I was afraid that dust might have passed through the filtration.Can that cause scorings ?

 

[cgraham1]

If you open up the muffler, factory tuning no longer applies.

 

[cgraham1]

...dust might have passed through the filtration.Can that cause scorings ?

Yes, but it will usually be more on the intake side. Take the muffler cover off, and see if you can actually feel anything on the piston. If it's oil residue it will just wipe off, if it's scoring you should be able to feel the lines in the piston.

 

[old guy]

I have a 440 that ran just fine, but I put a dual port muff. On it and that alone brought the idle up to about 4500 rpm, it was 4 stroking greatly out of the wood so I leaned it out and it still 4 stroked out of the cut, the tac said 14300, I leaned out a little more and this closed the h screw off, now the tac reads 14500, I think it needs a carb kit.
the saw runs great, I set the idle back to 3800-3000, I don't know where it's getting all that fuel with the H screw shut off

 

[floriceeel]

this is exactly how the thing looks.are these scorings or just some minor friction marks that hava no importance ?

 

[old guy]

That cyl. Looks excellent, nothing wrong there.

 

[floriceeel]

Tought that the small vertical traces above the exhaust port are scorings.I am very relaxed now,I'm starting to love that saw again.

 

[floriceeel]

Nothing lik

Yes, but it will usually be more on the intake side. Take the muffler cover off, and see if you can actually feel anything on the piston. If it's oil residue it will just wipe off, if it's scoring you should be able to feel the lines in the piston.

Nothing like that,I pulled the top end to check and it is very smooth,but those aren't oil traces neither

 

[floriceeel]

I have a 440 that ran just fine, but I put a dual port muff. On it and that alone brought the idle up to about 4500 rpm, it was 4 stroking greatly out of the wood so I leaned it out and it still 4 stroked out of the cut, the tac said 14300, I leaned out a little more and this closed the h screw off, now the tac reads 14500, I think it needs a carb kit.
the saw runs great, I set the idle back to 3800-3000, I don't know where it's getting all that fuel with the H screw shut off

So 13.5 k shouldn't be an issue...strange things happening