I got KraftyHDs MS650 in the mail today. The running issues was a simple fix but he wanted me to look it over. The 90* plastic elbow was not plugged into the fuel line in the top of the tank.
More importantly, here are some things I found with the BB kit. I put the saw back together using a new 660 gasket. The piston skirts were hitting the gasket, just b a r e l y. Luckily I had another, so back apart it came and the next one went in after I relieved the ID of the gasket a little. I still wasn't sure the piston wasn't touching the case. I put it back together and it's smooth as silk. I turned it over with my fingers on the flywheel back on forth past BDC and there's nothing there. It clears but not by much. That's why the skirts on this kit are .080 shorter than stock as Excess650 I think it was showed earlier today. The bottom of the piston does free port perhaps .020" at TDC, just like mine does. But it starts, idles, and accellerates great.
Here's another thing I found that I really don't like. The roof of the exhaust port is totally flat. I mean no curve to it at all. This flies in the face of everything I've learned about porting. I do not like to raise the roof of an exhaust port but I felt like I had no choice on this one. It's simply not worth the risk of leaving it flat. It only took raising it about the amount of the original bevel to get a little curve to it. Grant it, the original bevel was quite large. That's probably how they get away with such a flat roof. I can see why some ported saws break rings. Go ahead and widen that port and maybe loose a little of that factory bevel and you've got the recipe for a failure if you don't change the shape a little. It doesn't take a lot to make a difference. So builders beware. Fix that port shape when you port these things.
I've put it through a couple heat cycles and hope to get it in some wood tomorrow. After that it'll be back on its way back home.
