When to replace a piston?

[Vintage Engine Repairs]

My 020av has just started to develop audible piston slap. I decided to tear the saw down and find out the clearance between the piston and cylinder so be able to record at what wear the piston knocking / slapping becomes noticeable and when therefore it should be changed. I hope you enjoy the video.

 

[awful knawful]

I just got a cs2166 in a box. Piston broke. Clearance was .010 - .021
Guys on here told me .0015 to .004

 

[Vintage Engine Repairs]

I just got a cs2166 in a box. Piston broke. Clearance was .010 - .021
Guys on here told me .0015 to .004

I’m working in metric with my numbers haha

 

[awful knawful]

I’m working in metric with my numbers haha

One inch is 25.4 mm.

So acceptable is .04mm to .1mm

I had .25mm to .53mm depending where I took the measurements.

 

[Vintage Engine Repairs]

One inch is 25.4 mm.

So acceptable is .025mm to .1mm

I had .25mm to .53mm depending where I took the measurements.

Gotcha if you measure the very bottom of the skirt thrust side and then measure in the cylinder where the skirt meets the wall when the piston is at TDC.

Either way, that’s great data! Good to know above .25 you’re in dangerous territory!

Here are my 4 saws that I have measured.

020av - 0.131mm
020avp - 0.171mm
056 super - 0.301mm
08s - 0.19mm

All run and all have good power! Just different levels of noise. Only saw I’m using is the 020av. The rest either I’m waiting for new pistons or have already replaced them.