Don Terrill’s Speed-Talk

Matt80 wrote:So aren't the mains a bit short on clearance?

Nope, just about right.

And what about this wear? Nothing to worry about?

That spot might have had some debris under bearing shell.

Block has lightly warped after line boring, totally normal and harmless. You can line hone main bearing line and get rid of those marks - but will get bigger main bearing clearances in that trade - not better situation than what you have now. Line boring to bigger bearing will fix things - but will need bigger outer surface bearings. You have not problem with current situation so better to keep it that way.

About the fuel wash/map issue, I read somewhere that rpm limiter with ignition cut only could have caused that wear on pistons/cylinders: do you agree? Thanks

Yes, unburned fuel will cool piston and cylinder and fuel will be condensed everywhere. Man should always cut fuel together with ignition when hitting hard limiter.

This is the back of those main bearings:




And these are the conrod ones:





even here there are some marks and discolourations