Stihl 075

[Kidneycutter]

Well, if anybody read the last post regarding this saw they'll remember I was milling some oak when the saw lost power. When I took the saw out of the cut I realised the exhaust had blown off.
Anyway, as advised, I took the cylinder off and there is very light scoring on both sides of the piston. The cylinder is smooth. Can I clean up and carry on using? Or should I invest in a new piston?
Thanks,
Clem

 

[TheTone]

My approach would be to clean up the cylinder with Scotchbrite, making sure there's no aluminum transfer, check port and transfer edges, make sure the rings are free, and remove them. Then polish the piston lightly with fine grit sandpaper to remove any raised areas in the light scoring. Check skirt/cylinder clearance and ring gap. Since you've got it apart, this would be a good opportunity for a new set of Caber rings, unless the ring gap is excellent. Clean all parts well. reassemble and go.

 

[Kidneycutter]

Thanks for the reply. I've taken the piston off and the rings are are really sharp..cut my finger on the edge. Must be creating a burr? Anyway, checked the shaft and I think there's a bit of movement on the clutch side bearing...I assume this might cause the uniform scoring around the piston?
Will double check but looks like I'll have to pull the saw apart and replace bearings,seals.......

 

[jltrent]

New piston and a better air filter, pressure test also as with the age of that saw impulse lines, intake boot, oil seals and any other seals could be dry rotten. On the air filter with slight damage on both sides of the cylinder tells me it is eating saw dust.

 

[Kidneycutter]

The air filter is a new Oem plus I changed all the gaskets so definitely no dust sucking through there. Can it be sucked through the exhaust on the de compression stroke?
Any ways, play in shaft so need to split and replace.
Question is Oem or aftermarket? I could spent a lot on Oem parts bearings,oils seals, gaskets and piston is going to cost £200.
Can I use aftermarket parts, I did on my 051 gaskets ans seals, and it seems to run ok. I'm not sure about the bearings and piston.
The aftermarket pistons always seem lighter to me..plus are the different Pistons for this saw a,b,c?
Cheers

 

[TheTone]

My approach would be to clean up the cylinder with Scotchbrite, making sure there's no aluminum transfer, check port and transfer edges, make sure the rings are free, and remove them. Then polish the piston lightly with fine grit sandpaper to remove any raised areas in the light scoring. Check skirt/cylinder clearance and ring gap. Since you've got it apart, this would be a good opportunity for a new set of Caber rings, unless the ring gap is excellent. Clean all parts well. reassemble and go.

My apologies for the incomplete advice. I guess my mouth was ahead of my brain. I stand by what I said except for the egregious omission of the most important step of all - namely finding out what caused the mild scoring to begin with. Fortunately another member fixed my goof.

 

[chilipeppermaniac]

The air filter is a new Oem plus I changed all the gaskets so definitely no dust sucking through there. Can it be sucked through the exhaust on the de compression stroke?
Any ways, play in shaft so need to split and replace.
Question is Oem or aftermarket? I could spent a lot on Oem parts bearings,oils seals, gaskets and piston is going to cost £200.
Can I use aftermarket parts, I did on my 051 gaskets ans seals, and it seems to run ok. I'm not sure about the bearings and piston.
The aftermarket pistons always seem lighter to me..plus are the different Pistons for this saw a,b,c?
Cheers

2 and 3/4 years gone by and no news on how the saw turned out, unless another thread elsewhere contains updates from kidneycutter