What's on your bench today?

[spudulike]

:lol:

as always spud u have a pic for everything and great at explaining things

 

Thanks Martin,

Re the problem, get a photo up, you can get some strange effects that I put down to the flow of exhaust gases and the way the earth electrode gets in the way of them!

[Ryan]

Using an MS240 on saturday, I had set saw down to move some brash when I heard a rattle from engine just for a second then the saw stopped. I tried to pull the started cord gently but saw would not turn over. On inspection the top section of the piston was broken along with the top ring just opposite the exhaust port.

 

Looking closely at the piston after removal, the top compression ring has turned past the retaining post in the groove right round so that the gap in the ring was opposite the exhaust port, where it obviously has caught the port and as a result broke the piston and ring.

I believe the pin which prevents the ring from turning in the groove has worked loose and worn both pin and the hole it locates in enough to let the ring turn. This saw was rebuilt 3 months ago including bearings seals gaskets and a GOLF piston kit. Was this a faulty piston or did I do something wrong. Locating pins were at the intake side and rings were gapped in the bore before fitting. It was in the original cylinder which was sanded clean to remove previous alloy transfer marks. Cylinder looks fine still apart from a small burr on the exhaust port obviously damaged when the ring broke.

 

Photos

 

 

[spudulike]

Using an MS240 on saturday, I had set saw down to move some brash when I heard a rattle from engine just for a second then the saw stopped. I tried to pull the started cord gently but saw would not turn over. On inspection the top section of the piston was broken along with the top ring just opposite the exhaust port.

 

Looking closely at the piston after removal, the top compression ring has turned past the retaining post in the groove right round so that the gap in the ring was opposite the exhaust port, where it obviously has caught the port and as a result broke the piston and ring.

I believe the pin which prevents the ring from turning in the groove has worked loose and worn both pin and the hole it locates in enough to let the ring turn. This saw was rebuilt 3 months ago including bearings seals gaskets and a GOLF piston kit. Was this a faulty piston or did I do something wrong. Locating pins were at the intake side and rings were gapped in the bore before fitting. It was in the original cylinder which was sanded clean to remove previous alloy transfer marks. Cylinder looks fine still apart from a small burr on the exhaust port obviously damaged when the ring broke.

 

Photos

 

 

 

Probably just a faulty piston with a loose location pin, it does happen even on OEM pistons - Golf are generally not a bad choice piston - better than many!

[Rich2484]

That looks nasty.

 

Take it the pot is worse.

 

Could rebuild it again if you have the time.

[Ryan]

The pot is actually fine apart from a small burr on the exhaust port where the ring must have caught. I think the fact the saw was at idle when it happened really reduced damage to a minimum. I would hope to have it going again by Wednesday. I cant be without it at the minute

 

EDIT should I try the supplier for a replacement free of charge. Think it came from GHS.

[High Scale]

Waiting on some fuel lines.

Edited June 30, 2013 by High Scale

[burrell_]

where did u get the piston from in the end

[agg221]

EDIT should I try the supplier for a replacement free of charge. Think it came from GHS.

 

I would, particularly if you can find the receipt or other proof of purchase (even electronic). You at least want to be sure where you got it so you aren't getting 'free' parts from the wrong supplier.

 

I believe GHS offer a 1yr warranty and your photos prove it wasn't lean seized through a fuel issue. I would ring them up, explain what happened and offer to email them the photos. My guess is they will send you a replacement FOC by return.

 

Alec

[High Scale]

where did u get the piston from in the end

 

The German guy on the eBay link you sent me.

 

Cheers!

[burrell_]

Good good can u get a vid of that 166 milling please