660 clone build

[MustangMike]

I pulled the cylinder, Kinda hard to tell, but I think it is just the piston pin bearing, guess if it is I got lucky!

 

[T.Roller]

The AM worm gears are junk

 

[Glock37]

We ran these at the tn gtg and they ran flawlessly

Thanks for the heads up

Most of us where running 32 or 40 to 1 mix

I was running 32 to 1 belray

 

[Gravedigger]

We ran these at the tn gtg and they ran flawlessly

Thanks for the heads up

Most of us where running 32 or 40 to 1 mix

I was running 32 to 1 belray

Mine was running 40:1 bel ray avgas

Picture of plug when crank went.

 

[Flyguy]

The rod bearing failure is from an inferior bearing that starts to fail upon the first startup.

Man, that sucks. It sure got hot on the PTO side. This has me convinced that upgrading the main bearings to OEM might not be a bad idea after all. I hate to put a bunch $$$ into a knockoff saw, but I don't want to have to do a lower end overhaul on it all the time either.

 

[94BULLITT]

Man, that sucks. It sure got hot on the PTO side. This has me convinced that upgrading the main bearings to OEM might not be a bad idea after all. I hate to put a bunch $$$ into a knockoff saw, but I don't want to have to do a lower end overhaul on it all the time either.

There are two ways to look at it. If you upgrade the crank bearings and the big end rod bearing goes, you may need crank bearings, and really they should be replaced. If you don't upgrade them, they could be what fails and destroys everything else.

 

[Flyguy]

Yeah, very true. I think I'll upgrade the crank bearings to OEM, and hope the lower rod bearing plays nice. I've got an OEM wrist pin bearing on order.
Just out of curiosity, what rpm did you have your high speed set at? I was thinking about setting mine around 12,800, using a 40:1 mix.

 

[94BULLITT]

I never put a tach on it. It was probably around 13,000-13,500. I had been running it richer prior to this.