066 Magnum Big Bore Project

[BobL]

066 BB kit revisited

Well I finally got around to fitting my free replacement 066 BB kit this evening. the main reason it took so long was I took the opportunity to order a bunch of other stuff from Baileys and the order got held up waiting for a back order on a small item so it only arrived 2 weeks ago. I was not fussed as I was more than occupied with a new 880 and 441 and a bunch of milling activities.

So I put on the new BB kit.
- Piston skirt easily clears the replacement base gasket (that was a problem last time)
- 155 psi cold compression
- Full crankcase pressure and vacuum test all passed fine
- Squish - its 0.033" and 0.034 - sound like too much?

I was thinking of try the previous base gasket (that gave me 0.022 and 0.024" squish with the original BB kit). I've already taken a mm of so off the gasket ID using a Dremel so it easily clears the piston. I have a surface plate so alternative is to take 0.015 off the jug base?

 

[skid row]

For the price I can't complain, but it's no where near the quality of an OEM part.[/QUOTE]

You got that right.

 

[blsnelling]

I've never seen that much squish on a 066BB. Maybe you got the new revised version. Does your piston freeport at the bottom of the exhaust port at TDC?

 

[epicklein22]

I've never seen that much squish on a 066BB. Maybe you got the new revised version. Does your piston freeport at the bottom of the exhaust port at TDC?

My squish was around there too. I was a bit surprised. I am using the Baileys gasket, maybe that is the reason?

 

[excess650]

I've never seen that much squish on a 066BB. Maybe you got the new revised version. Does your piston freeport at the bottom of the exhaust port at TDC?

I know that you're questioning BobL, but my last kit showed that much squish with .5mm base gasket, and did freeport at TDC. I would prefer a piston with a longer skirt even if I have to massage it to work.

 

[blsnelling]

My squish was around there too. I was a bit surprised. I am using the Baileys gasket, maybe that is the reason?

How thick is their gasket. With the OEM gasket I've been seeing <.020" squish. The OEM gasket is about .018" thick.

 

[epicklein22]

How thick is their gasket. With the OEM gasket I've been seeing <.020" squish. The OEM gasket is about .018" thick.

I don't know. I have both OEM and the Baileys. They looked identical when comparing. I just grabbed the Baileys one because it was right in front of me. As for the squish, I am not using digital calipers, so factor in a little error here, but not much.

 

[excess650]

My Bailey's BB kit didn't come with a gasket. I ordered their gasket kit seperately, and it had both the 1mm and .5mm gaskets included. The 1mm appears to be rubber coated steel, and the .5mm plain steel.

 

[epicklein22]

My Bailey's BB kit didn't come with a gasket. I ordered their gasket kit seperately, and it had both the 1mm and .5mm gaskets included. The 1mm appears to be rubber coated steel, and the .5mm plain steel.

Ya, I ordered a gasket kit separately also. No gasket in the set. My kit however only came with the rubber coated cylinder gasket.

 

[blsnelling]

Ya, I ordered a gasket kit separately also. No gasket in the set. My kit however only came with the rubber coated cylinder gasket.

Never seen one come with a gasket either. If it was coated, perhaps it was the 1mm one then. No wonder you have so much squish.

 

[excess650]

epicklien22, PM sent

 

[BobL]

There was no gasket with either my original or replacement BB kit. For the first kit Bailey's were out of gaskets so I used a new stihl 066 gasket. For the replacement kit I used the gasket from a the Bailey's gasket kit which has a significantly larger ID than a standard gasket.

8 am this morning I fired it up for about a minute - can't run it any longer here - inner city neighborhood and all that. I was just keen to see if the high end vibe I noticed before with the previous BB on this saw was still there - it wasn't so it was wasn't a bent con rod, and was almost certainly the bottom of the skirt contacting the gasket at high revs. I'll run it for a bit when I go to the yard next week, and then bring the squish down a bit.

Thanks for all your comments and help.