660 top end rebuild

[Wrangler]

I think i remember a discussion a while back about leaving gasket between crankcase and cylinder out and just using sealant. Has anyone had good luck with this?

 

[chiselbit]

@Barc Buster

 

[96coal449]

I think i remember a discussion a while back about leaving gasket between crankcase and cylinder out and just using sealant. Has anyone had good luck with this?

It's a common practice among saw builders. It will raise compression.
The term ''squish'' comes to mind.

 

[Wrangler]

Cool thanks! I thought I remembered hearing that but just wanted to make sure!

 

[Wrangler]

Anyone know torque specs for head bolts/screws?

 

[Jehinten]

Anyone know torque specs for head bolts/screws?

I don't know the specs, but I'd recommend replacing with new bolts. I did not replace mine on a 661 rebuild and ended up having a couple back out. They use a texture under the bolt head (there's probably a specific name for it) that bites into the aluminum to hold the torque and to prevent the bolts from backing out. New bolts stopped them from backing out/ loosening

 

[Barc Buster]

Yes you can remove the base gasket. You’ll want to measure the squish to ensure the piston doesn’t slap the cylinder head. The squish is the distance left between the base of the cylinder head and the crown of the piston at top dead center. You measure this by sticking 2-4 pieces of thin solder to the top of the piston with some grease. You can get away with 2 pieces located above the piston pin ends. You then carefully mount the cylinder and torque it down. You then run the piston through a couple revolutions of the crank to squish the solder. You then remove the cylinder and measure the thickness of the squished solder. This gives you your squish measurement. Ideally for a bigger saw like a 660 you’d want to shoot for a .020+ish squish.

When you seal the base of the cylinder to the case you want to use something like Dirko or yamabond. Don’t use rtv silicone or the like.

I’ve never done a 066/660 you may want to consider starting a thread over on the opeforum. You’ll get great advice from a few solid saw builders over there.

 

[Wrangler]

Thanks guys ,ggod stuff! I like the solder trick, that’s slick! I actually reused gasket , i just flipped it over. I’ll retorque head bolts tomorrow night and order some new ones. I have 2 more 660s to do so this is much appreciated advice

 

[Fivepoints]

Thanks guys ,ggod stuff! I like the solder trick, that’s slick! I actually reused gasket , i just flipped it over. I’ll retorque head bolts tomorrow night and order some new ones. I have 2 more 660s to do so this is much appreciated advice

Reusing the gasket is asking for air leaks

 

[Wrangler]

Reusing the gasket is asking for air leaks

Yes,I didnt want to but saw broke Friday and I need it today to finish big tree so no time to order. Im stocking up on good parts for next builds though.

 

[Dan Cobb]

... I have 2 more 660s to do so this is much appreciated advice

Three 660s that all need rebuilding? Sounds like there's more to this story.

 

[Wrangler]

One is actually a 650 i bought new in 2005 i think, other one ibe had for 10 plus yesrs. I just dont want to spend 1500 on a new saw right now

 

[Bart_]

First time I've ever heard someone else reference Yamabond

 

[Fivepoints]

First time I've ever heard someone else reference Yamabond

Yamabond works great. Ive used it a bunch myself. Working at the Yamaha dealer for a couple of years when i was younger probably had something to do with that.

 

[Barc Buster]

First time I've ever heard someone else reference Yamabond

Yamabond works great. Ive used it a bunch myself. Working at the Yamaha dealer for a couple of years when i was younger probably had something to do with that.

Yep great stuff. Although most recently I’ve used the permatex anaerobic gasket maker stuff. Seems to work pretty good.