Cylinder problems.

[Megatron]

Looks like I missed all the fun

 

The missing plating on the first cylinder is usually caused by abrasive dust getting in. Possibly due to;

-improper filter maintenance

-improper filter i.e. using the winter mesh filter instead of the summer fleece one.

-cutting in sandy or fire damaged (i.e. partially burnt wood) conditions.

 

You see that type of wear in cut off saws all the time.

 

Its open ported so a small saw or a non pro saw - possibly a 020T but is difficult to tell the size of the bore - not a 240 0r 200T - the 240 is closed port and the MS200T has a divider in the transfer port to help guide the fuel oil mix.

 

The MS240 has open ports, it just looks like they are closed when viewing the cylinder externally. For interest sake the old 020AV (all metal) had closed ports.

 

I am suprised no one used the spark plug as a guide to estimate the bore

 

The second cylinder looks like the plating is flaking off instead of being rubbed off, as was the case with the first cylinder. Considering the rest of the cylinder doesn't appear too bad, it might actually have been caused by a flaw in the plating. The plating may not have been adhered to the aluminium very well in that area of the cylinder. Heat is usually the reason it eventually flakes off though. If the plating continues to flake and reaches the exhaust port it will exacerbate the problem, due to the nature of the ring travel.

 

Would like to see a picture of the piston (in the area that matches the damage to the piston.

[Megatron]

The first two are of an MS240.

Third; ingested dust damage in cut off saw.

Final; 020AVS

[spudulike]

I was assuming that because the 026, MS260 and 024 were closed port, the MS240 would follow but it looks like it has the cheaper open ports.

 

Looks like I was right with the 020T (MS200T forerunner and not the 020AVT!)

 

What about the last one - was it the 320XP?

[Megatron]

I don't think all 024 cylinders were closed port. I wouldn't mind betting the 024WB wasn't or perhaps some of the later ones nearer to the MS240 introduction. Here is a 024 with closed ports (early version, shortly after Stihl stopped using the single ring piston);

 

The second cylinder must surely be the 3120XP. The spark plug makes it 60mm. It certainly isn't from a Stihl. By the looks of the finish I would say it was made be Kolbenshmidt (KS)?

[spudulike]

Got an early one with closed ports - got another but not torn it down yet!

[Mesterh]

That must be the Husqvarna 3120XP then - thought those ports looked a little good for an older saw:001_rolleyes:

 

RE - 020T - loks like cleaning the air filter regularly would solve the issue - dousing in hot water and one of these bubbling fabric cleaners is a good idea.

 

The other one looks like the plating has come off and the piston is bluing the surrounding area due to overheating - will be fine until the plating starts coming off above the exhaust port - your compression will drop off then and it will finally die:thumbdown:

 

Good to know that a saw can run with damage like that!

 

That's the one!

 

I am a bit lazy on the cleaning the filter front for sure, but in my defense they probably have done a serious amount of hours.

 

The 3120 seems to run just as good as ever for the time being, but I will keep an eye on it as I know it will need a cylinder one day.

[Mesterh]

Looks like I missed all the fun

 

The missing plating on the first cylinder is usually caused by abrasive dust getting in. Possibly due to;

-improper filter maintenance

-improper filter i.e. using the winter mesh filter instead of the summer fleece one.

-cutting in sandy or fire damaged (i.e. partially burnt wood) conditions.

 

You see that type of wear in cut off saws all the time.

 

 

 

The MS240 has open ports, it just looks like they are closed when viewing the cylinder externally. For interest sake the old 020AV (all metal) had closed ports.

 

I am suprised no one used the spark plug as a guide to estimate the bore

 

The second cylinder looks like the plating is flaking off instead of being rubbed off, as was the case with the first cylinder. Considering the rest of the cylinder doesn't appear too bad, it might actually have been caused by a flaw in the plating. The plating may not have been adhered to the aluminium very well in that area of the cylinder. Heat is usually the reason it eventually flakes off though. If the plating continues to flake and reaches the exhaust port it will exacerbate the problem, due to the nature of the ring travel.

 

Would like to see a picture of the piston (in the area that matches the damage to the piston.

 

No pics of the piston sorry, but I didnt see any damage or scoring.

 

When I replace them Ill post a few pics in here.

 

TBH I was surprised at the damage as it hasnt done a massive amount of hours and the filter is always fairly clean on this one.

[Mesterh]

Did a compression test on the 3120 today and it was showing 150psi which I think is a bit low but any info on what it should be?

[spudulike]

Did a compression test on the 3120 today and it was showing 150psi which I think is a bit low but any info on what it should be?

 

TBH, it depends on what gauge you use and what sort of valve the gauge has in it, generally anything over 120psi will run and 150psi isn't bad at all. I have had anything from 130psi to 240psi, the latter with a domed piston.

 

The compression will get better with use if a new piston has been fitted and is also higher on a fueled saw that is cold and the throttle is open - measuring with the decomp on will lower it a bit.

[Mesterh]

The tester is only a cheapo gunson but tried earlier on a 026 which is old but a good saw it read 160.

 

The 3120 is a runner but was cold.

 

I think i will order a new aftermarket pot and piston as it does/will need one and then try a comparison.