Reply To: Backfire/misfire thru carb

[Don]

OK well that little hole in the thermostat plate is a programmed bleed by, but it you look closely at the thermostats you will see a tiny “V” notch right in the top of the brass thermostat caps that allows a little bit of water to pass through even when thermostats are closed. Those two springs and plastic valves allow the higher pressure cooling water achieved at higher RPMS to push those relief valves open and let more cooling water through. So, oftentimes, engine temp comes down a bit at higher RPMs because more water is traveling through the powerhead due to the open relief valves. If anything, vents right at the top of the cylinder water jackets would be the best way to allow trapped air to escape.
In any event, that thermostat housing looks perfectly clean, so we must look farther down the line in the adapter housing to see what is plugged up. Like I say, not that familiar with the turbojet set up, but I am confident you can locate where the engine cooling water exits the adapter. I guess I would be inclined to blow backwards from the adapter cooling water exit with compressed air or high pressure water to free up whatever is plugged up. I can’t remember where that crazy exhaust elbow is located, is it on the adapter housing? If so, you may have to remove it to find whatever is plugging up the system…Disregard this if the exhaust elbow does not mount to the adapter housing….