workshop time

[spudulike]

Could anyone say how much workshop time would the book say it took to swap a pot and piston on an ms261?

 

As I think you probably now know, it isn't just the "Swap out Time", it is all the checks to make sure the new top end isn't going to go the same way as the first so pressure/Vac test, fuel pipes, breather, carb metering, pump diaphragm, guaze filter etc plus the final tach etc to ensure the saw will last for many years.

 

Do a straight swap and not caring too much about the end result - an hour may do it but if there is an issue not found, you will be doing the job again very soon!

[GardenKit]

As I think you probably now know, it isn't just the "Swap out Time", it is all the checks to make sure the new top end isn't going to go the same way as the first so pressure/Vac test, fuel pipes, breather, carb metering, pump diaphragm, guaze filter etc plus the final tach etc to ensure the saw will last for many years.

 

Do a straight swap and not caring too much about the end result - an hour may do it but if there is an issue not found, you will be doing the job again very soon!

I could not agree more Steve. I have been doing this job for years and never get close to some of the times quoted by people who have only done it once or twice.

But as you say, its not just the swapping, its the cleaning, testing, tuning, retuning etc, not to mention the time looking up part numbers and obtaining the bits.

[spudulike]

For the record - MS261 rev to 14,000rpm max, on a new top end 13,000 would be good for the first couple of months and then re-tach to circa 13,500 when bedded in.

[openspaceman]

For the record - MS261 rev to 14,000rpm max, on a new top end 13,000 would be good for the first couple of months and then re-tach to circa 13,500 when bedded in.

 

Unfortunately I didn't get the chance to recheck it, chap said it rattled a bit and stopped. Plug was chocolate brown , so a bit rich if anything and the rings were good, so I pulled the cylinder and found this:

 

 

Big chunk was long gone but I guess it caused the small piece to break away and it was this that was jammed between big end and crankcase. I wonder if the piston damage was related to my repair or what?

 

I couldn't find a meteor piston so let's see how a golf one fits, stihl piston is over 70 quid and would be a better bet in a newer saw.

[spudulike]

Unfortunately I didn't get the chance to recheck it, chap said it rattled a bit and stopped. Plug was chocolate brown , so a bit rich if anything and the rings were good, so I pulled the cylinder and found this:

 

[ATTACH]194176[/ATTACH]

 

Big chunk was long gone but I guess it caused the small piece to break away and it was this that was jammed between big end and crankcase. I wonder if the piston damage was related to my repair or what?

 

I couldn't find a meteor piston so let's see how a golf one fits, stihl piston is over 70 quid and would be a better bet in a newer saw.

 

Funny enough I have just answered a post questioning the materials used in pistons. It is possible this piston was to brittle or undersized and the slap at the bottom of the stroke shattered it!

 

What make was it?? Golf are generally pretty good but not as good as Meteor that I class as near OEM quality!

 

Pistons should use an aluminium/silicon mix or alloy, silicon is added in specific amounts to control thermal expansion. It is possible that this piston was fabricated from a more brittle/hard aluminium alloy mix!

 

Check the crankcase isnt cracked and the cylinder ports are not bruised. The rod may be bent but you will find out on reassembly!

[openspaceman]

 

What make was it??

 

As far as I can tell the saw was all original, cylinder definitely Stihl, 2 years old. As I said earlier in the thread it suffered from chronic over reving before it seized. The piston could have suffered then but it didn't seem damaged. It was resembled with the original gasket and the big chunk is from a section of the piston that cannot strike the crank.

 

I'm trying the golf piston from sawbits.

[spudulike]

As far as I can tell the saw was all original, cylinder definitely Stihl, 2 years old. As I said earlier in the thread it suffered from chronic over reving before it seized. The piston could have suffered then but it didn't seem damaged. It was resembled with the original gasket and the big chunk is from a section of the piston that cannot strike the crank.

 

I'm trying the golf piston from sawbits.

 

OK, OEM then......only seen one saw with similar damage and it was on a high hours MS260 that had that much piston slap, it actually shattered through fatigue.

 

Golf are OK pistons, just check it over before fitting but it should give some more life to the saw - not too much to lose!

[Eddy_t]

OK, OEM then......only seen one saw with similar damage and it was on a high hours MS260 that had that much piston slap, it actually shattered through fatigue.

 

 

 

Golf are OK pistons, just check it over before fitting but it should give some more life to the saw - not too much to lose!

 

 

I've seen a few 261 pistons that have shattered in the same way, probably a weakness in casting.