Cross Performance 066/064 660 piston and cylinder kit.

[fin460]

Randy @Mastermind sent me a prototype Cross Performance 066 top end this spring on the condition I do a build thread for it. I'm slow and I'm in the process of installing it now on a nice ms660 for a neighbor that he bought this spring with a blown top end.

 

[fin460]

 

[fin460]

When my neighbor first bought the saw I pressure and vac tested to find the only air leak was a leaking decompression valve. I cleaned the saw up and installed an aftermarket piston and cylinder in it while we were waiting for Cross Performance to produce a cylinder kit for a ms660.

The aftermarket cylinder kit I installed was a no name cylinder that I had on the shelf, I'm guessing that I bought it from ebay, the cheapest I could find.

Carl @Miller Mod Saws came over to test out a few saws one day and I grabbed the ms660 and made a video of him running it with a 28" bar in some oak.

When I finish installing the Cross Performance cylinder kit I will then make a comparison video of it with the same bar and chain in the same log.

 

[fin460]

Some initial photos of the cylinder and piston

 

[fin460]

 

[fin460]

 

[fin460]

The cylinder looked very clean to me, with excellent chamfered port edges. I then installed the piston, wrist pin clips felt like they held their shape well when I installed them with my needle nose pliers, and they snapped in tight.

 

[fin460]

Make sure the arrow on the piston is pointing toward the exhaust side. Put the cylinder gasket down before installing the piston. I learned that the hard way once.

I use a piston ring squisher thingy. I misplaced my larger one, and I was using one that was meant for smaller pistons. It worked but would have compressed the rings more uniform if I had the correct size of ring compressor for the larger piston.

 

[fin460]

I then ran into trouble trying to bolt the cylinder down next. They cylinder was made for a bolt pattern of an 064 case. I scratched my head on this for too long and then got busy and it was over a month before I went back to finish the ms660. I was trying to find an 064, but decided to just elongate they holes using an 066 oem base gasket as a template.

Randy told me it was made to bolt up to an 064, I'm not sure what bolt pattern the cylinders will be sold in, but I'm sure they will be correct per specified model.

 

[fin460]

I used a sharpie to mark the material that needed to be removed, I made sure the OEM base gasket was centered on the bore.

Part way there

To check to see if I was close enough yet, I would keep checking with the base gasket until all four bolts fell through the gasket freely.

Finished product

 

[fin460]

I bolted the cylinder down and checked squish in a couple places by sticking soldering wire down through the spark plug hole. I used .032 thickness wire, and it just barely squeezed it. My caliper isn't the most accurate, but I was consistently getting right around .028 for the squish. That sounded good to me for a bolt on aftermarket cylinder out of the box.

 

[fin460]

I then pulled and trimmed the limiters tabs on the H and L adjustment screw on the carburetor.

I stick a sharp screw in and twist it by hand until it gets tight. I then carefully turn it counter clock wise until I see the limiter tab line up with the slot in the carburetor housing, and then it pulls right out. I trim the tab off with a razor and reinstall, or throw it away. Same for each H, and L.

 

[fin460]

I put the saw back together and it fired right up. I took it back to the same log to make a video, but it was hot and humid, and I was having trouble reading my tune on the saw. I got scared it might have an air leak and I went back to the shop with out getting a video.

I'm going to pressure and vac test the saw this afternoon, and may test it out on some test wood, but its too hot for this fat kid to be out in the field with this large of saw.

 

[fin460]

I don't have much experience, so any technical questions anyone may have, should probably be asked here and anyone can chime in. I'm assuming Randy can get you the timing number the cylinder was designed around.

 

[huskihl]

That right there is badass

 

[fin460]

I made it out tonight after passing a pressure an vac test. The saw ran really well and consistent for me. I made a dozen cuts or so with it. It performs quite well.

 

[CR888]

Is it a true MMWS cylinder with monkey port design & timing? That would be a pretty nice bolt on mod if it were. I like the fact a Randy is getting close to the guys that cast cylinders. Cool stuff!

 

[smokey7]

Sounds a little rich still but nice job on the build. Looks like a nice bolt on kit. Good job to all involved.

 

[Glock37]

@Mastermind


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[Mastermind]

Glad to see this Justin. Thanks for doing a great thread.