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Help with engine ping

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Here's the deal: I have a 2012 CR250AF that I just can't get to run right at low throttle openings. More specifically when the engine is good and hot it will ping/knock just on slight throttle openings. Like 1/16 to 1/8. Like when cruising through the pits throttle openings. If I crack it open any more it runs great...good power and response.

This is a highly built trail motor:

Eric Gorr 295 with mo better porting

Set up for race fuel

About 230 psi cold

Fmf fatty with shorty silencer

Rad valve

39 mm pwk with jd jetting

All intake gaskets and boots are brand new.

Temps have been around 50 at zero elevation

Blue needle in #4

48 pilot

180 main

AS about 1.5

I've tried up to a 50 pilot but I loose the bikes ability to idle. Not even for a second or two and it's clearly too rich. Sluggish response and spooging all over. I've also tried an even richer clip but the bike starts to load up. The ping gets a little better but doesn't go away.

The motor has about 20 hours since a full crank up rebuild but honestly it's done this for most of its life. It almost acts like it's got an air leak but I havnt found one. I'm going to throw a new crank seal in this week to rule that out.

Any idea's?

Too much compression? Add a base gasket?

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