Mystery Challenge! 07 Vulcan Nomad head gasket?

[ReginaBud]

Hi Y'all. My 2007 Nomad is possessed and I need your advice. The rear head Gasket blew a few years ago and 'Mosquito fogging' occurred. Bike was tore down, Heads were verified/made flat, new gaskets, etc. Rode for almost 1000 miles no problem. Bike started to overheat while on the Highway one day. Limped home. EVERYTHING coolant related was checked. Rad Flushed, hoses good, thermostat good, new rad cap tested to 19 pounds, fan working (manual switch), system holds pressure for 15 minutes, etc. If you run the bike at idle, it will not overheat. There is NO smoke/steam out the tail pipes ever. Bike runs GREAT.

Here is the crazy part; Once the bike is warmed up and I am watching the overflow tank, if I gun the throttle over 3500 rpm there is IMMEDIATE bubbles in the system and the tank starts to overflow every time I gun the engine. But still no white smoke ever out the exhaust.

I need your sage opinions: What it looks like to me is that there is a leak in the head gasket that only occurs at higher cylinder rpms (and pressures) that injects exhaust gases into the coolant system! And the damn thing acts like a one way street so the fluid never gets into the exhaust when the pressure drops! I noted when I tore the coolant system apart that the return hose to the front cylinder had some white crap in it that the rear one didn't so I suspect the front cylinder is the naughty one.

Has anyone ever seen a batshit crazy head gasket issue like this? What else could it be? I am thinking I need to tear down the head and inspect/replace the gasket?

Thanks for your feedback and advice in advance. This problem has driven me around the bend.

Cheers,

Bud