I decided to check the fuel levels in my carbs yesterday after finally remembering to get hold of some transparent hose. All of the carbs have the fuel level set at the same height which is inline with the marker on the side of the carbs. The manual suggests that the level should be 4.1 to 5.2 mm below the line.

The line on my carbs slopes a bit as if the carbs are not as vertical than they should be. I don't know if the engine mountiing angle is slightly different in my car than on the bike.

What might the effect of too high a fuel level be on the carbs / engine?

Flooding , rich mixture , poor fuel economy, if they are bike carbs it can effect the mid range drastically.

in extreme FIRE HAZARD

It is definatly not running rich at full throttle. I am planning to fit a dynojet kit at the weekend, if it arrives in the post, so I will adjust the heights then. I was just curious.