Sprocket issues?

[Ledburyjosh]

I have noticed that my chain is going tight and loose as I rotate it.

 

It happens on multiple chains and bars on the same engine unit. So can say its the sprocket end being the issue. It also oil's fine and had some new pin bearings in today.

 

I've had this before due to a worn sprocket .

This time though the sprocket is pretty new. So I would have expected this.

I shall replace it anyway to be sure. But not until next week now.

 

So in the mean time does anyone have any suggestions of what to check? Could the drive shaft be out? And if so could that be checked?

 

 

Thanks

[spudulike]

most of the time it is just uneven wear in the chain that causes the symptoms you have. 

[Ledburyjosh]

6 hours ago, spudulike said:

most of the time it is just uneven wear in the chain that causes the symptoms you have. 

OK.

 

I shall try a new chain also to be sure.

 

I'm not convinced though as I have tried 2 bar and chain combinations. Unless both are worn? 

[Ledburyjosh]

A new chain does not remedy it.

 

I marked the distance the chain moves between each loose bit. And it matches the circumference of the sprocket.

 

So it's definitely relating to something around the sprocket.

 

I'll put a new sprocket and clutch plate on next.. 🤞

 

 

[openspaceman]

Bent crankshaft?

[bmp01]

Cranks not rotating though when youre pulling the chain round by hand.

 

Points to eccentricity in the clutch housing or rim sprocket. Or the interface between the two - the rim sprocket is a loose fit on the clutch so it will 'walk' around on the drive teeth as the chain is pulled round by hand (probably locks up in one position when the engine is turning it over at speed).

 

[Ledburyjosh]

8 hours ago, bmp01 said:

Cranks not rotating though when youre pulling the chain round by hand.

 

Points to eccentricity in the clutch housing or rim sprocket. Or the interface between the two - the rim sprocket is a loose fit on the clutch so it will 'walk' around on the drive teeth as the chain is pulled round by hand (probably locks up in one position when the engine is turning it over at speed).

 

I have come to the same conclusion. A new rim sprocket was fitted today and the issue still persists. So the next and last thing to change will be the bit the rim sprocket goes on.. unsure of the name of that bit.

 

Hopefully that's the fix.

 

Odd as it's been on for a while, I can't see what would cause it to change shape slightly.

 

Either way if I replace that then it would have had new clutch bearing and sprocket kit. Which doesn't leave much else...

[Dan Maynard]

Is it a big change or just a bit? Some variation is natural, the sprockets aren't precision components.

There is a chance you're seeing the problem because you started looking for it.

[spudulike]

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.

[Ledburyjosh]

2 hours ago, Dan Maynard said:

Is it a big change or just a bit? Some variation is natural, the sprockets aren't precision components.

There is a chance you're seeing the problem because you started looking for it.

I started looking for at as recently my saw has started getting stuck in cuts, particularly angled cuts on gobs. Which is has not done before and my sharpening is always consistent with guides etc.

 

The slackening of the chain would explain this.

 

Nonetheless I shall stick the chain back on and get a picture to get some more opinions and input