Stihl MS 660 Big Bore First Video and Post Mortum

[tallfarmboy]

Here is a close up of the granulation in the forging.

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Those pictures show a lot... Looks similar to a MIG weld with no shielding gas... lots of impurities. I feel that the slight over-revving lean condition caused the casting errors (which look to be right at the base of the pin) to release the chunk of piston that is attached to the pin on that side. That allowed sideways pressure to be put on the rod, which broke with the upward inertia of the piston. Then you had the top of the rod and pin floating around in the case which caused the rest of the carnage.

My $0.02 ... Bailey's Customer Service is golden.

 

[Mastermind]

Yeah, that ain't pretty.

 

[Meadow Beaver]

Here are the pics...



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Well what is left of the rod is definately strong because it sliced the crankcase like a knife went through it.

 

[parrishturf]

Update on the new build.

Well I received the new BB kit quite sometime ago. Bailey's was prompt and on the ball. Now I am waiting on the cases, oddly no word on the backorder. More to come...

 

[parrishturf]

Baileys Came Through!

Gregg,

Thank you for your support with my 660 BB. All the parts are here including the new cases with bearings.

I am building it up today!

 

[parrishturf]

660 resurection...

I put the crank case together today and installed the new Baileys BB piston and cylinder, along with the aftermarket crank.

I checked my squish and with the Kits base gasket installed I have .029" of squish.

The jug has only had the transfer ports pointed towards the intake and chamfering of all ports.

After watching Mastermind's build and considering the options with the exhaust port I have decided to take a new tact with this saw.

I want to experiment with utilizing a wider powerband. The last build turned rpm and still cut but well it blew. So before I move the ports or tighten the squish, or even polish the exhaust, I will cut with it as a primary saw.

After rethinking things with a long stroke saw chain speed from rpm may not be the best way to go. The torque may be better used with a higher tooth count drive sproket or rim.

Any advice on 9 or 10 tooth rims on a 660?

 

[parrisw]

I'd stick with 7 or 8t for a work saw, especially stock, 660's aren't that powerful.

 

[Mastermind]

A 9 pin on a work saw would be a bit much if it would pull it I figure.

 

[tlandrum]

maybe if it was an 880 with 20'' bar work saw

 

[Mastermind]

maybe if it was an 880 with 20'' bar work saw

And stuff!!!

 

[blsnelling]

Any advice on 9 or 10 tooth rims on a 660?

Don't waste your time or money.

 

[tlandrum]

And stuff!!!

and junk