I'm a heavy reader of this forum but, caused I'm not a english native speaker, I posted very few posts. This time I'd like to ask some useful tips about a major overhaul I'm performing on my Castor CP500 chainsaw.
Let's start from the beginning.
The reason I decided to perform such a task on my chainsaw is an air leak I noticed last time I was cutting firewood: chainsaw would not rise rpm when I squeezed throttle, then almost impossible to adjust carb as the symptoms remained; and at the end as I tilted my saw to the left/right, idle rpm started increase!
So I decided to replace oil seals, rebuilt carb, and so on. Removing the old oil seals has been almost impossible for me: I tried a lot of stuff, but without any success. So I decided to split the engine and carry out a complete overhaul.
Disassemble was pretty easy, but I found some surprises on which I'd like to recevice some tips from you.
Inspection results
Cylinder inlet side view
Cylinder
Piston exhaus side
Piston inlet side
Piston inlet side and top view
My questions are:
Let's start from the beginning.
The reason I decided to perform such a task on my chainsaw is an air leak I noticed last time I was cutting firewood: chainsaw would not rise rpm when I squeezed throttle, then almost impossible to adjust carb as the symptoms remained; and at the end as I tilted my saw to the left/right, idle rpm started increase!
So I decided to replace oil seals, rebuilt carb, and so on. Removing the old oil seals has been almost impossible for me: I tried a lot of stuff, but without any success. So I decided to split the engine and carry out a complete overhaul.
Disassemble was pretty easy, but I found some surprises on which I'd like to recevice some tips from you.
Inspection results
- Rolling bearing must be replaced as they run, by hand, very bad. It's very surprising to find out only after disassamble that bearings are to be replaced.
- Piston. I realize that all the symptoms my saw was showing are to point a lean running way. But I stopped pretty early in order to avoid any further damages. So after inspecting piston, I've found a couple of some scores on the skirt together with some black carbon dust on the top and heavy brown color on the skirt
- Cylinder shows a very small scratches (only a couple). Touching them by finger I cannot feel nothing
Cylinder inlet side view
Cylinder
Piston exhaus side
Piston inlet side
Piston inlet side and top view
My questions are:
- Do I need to replace the piston?
- Piston ring and cilinder clearance: I measured about 0,50 mm at ring tips once inserted inside the cylinder (45 mm piston diameter). Do I need to replace the piston ring?
- Why so much carbon buit up? Maybe of my 3% oil/fuel mix?