Sprocket issues?

[Ledburyjosh]

38 minutes ago, spudulike said:

What saw is it? The early MS261s and MS362s didn't have the best cranks and knocked the bearings and sprockets out regularly.

Strange it wasn't the chain, most times I see this symptom, it is the chain.

It is a MS460 2009 model.

 

Yeah I'm confident it's not the chain. I've tried x2 chains on a 25" bar and x1 chain on a 18" bar. They all do the same.

 

As as above on one of the pictures I posted with the blue marker pen lines on the bar. The loosening of the chain happens at set intervals which relate to the circumference of the sprocket. I.e. every tike the sprocket is back in the same place the chain is loose 

 

I'm all up for any suggestions to look at though, I'm no expert, just saying what I observe 

[spudulike]

The 460 is a solid machine so no underlying issues in its build.

I guess if I had one on the bench and had tried different bar, chain and sprocket combinations...USING OEM PARTS, I would get the verniers out and measure the distance from the sprocket to a fixed datum such as the first bar stud and rotate the rim taking measurements to see if there were any changes. You could then rotate the crank and see if you get any movement.....this is extremely rare but have seen twisted cranks on two machines - it looks pretty weird as the crank centre sort of wobbles as the crank is rotated.

Is the crank genuine OEM Stihl? Do you know the machines history? 

I take it your sprocket, bearing and rim are OEM? I have seen all sorts and some aftermarket stuff is pretty poor TBH!

 

[Ledburyjosh]

The machine has been mine since new and has not had any issues/major repairs.

 

The most likely reason is as you have pointed out, the sprocket is not OEM.

The rim sprocket replaced yesterday now is, however it's the bit that slides on is still a farmertec one.

 

That will be changed next. I shall report back once I have a replacement OEM part.

 

Thanks so far for the input 

[Muddy42]

I also would try and measure how much the sprocket is out of line whilst rotating it. Clamp the saw to a table and then use vernier Calipers, or just calipers or you could DIY by clamping down a knitting needle or something pointy that just touches the sprocket.

[Dan Maynard]

11 hours ago, Ledburyjosh said:

I started looking for at as recently my saw has started getting stuck in cuts, particularly angled cuts on gobs.

That sounds a bit strange, the chain would have to be getting really stuck to stop a 460. Sounds to me more likely something in the clutch or drum not transmitting the drive, which I guess comes back to that farmertec drum. Next thing to try.

[lurch_917]

i know it may sound daft but have you changed the plastic caged roller bearing ? as i had it once where one of the needles went .