[Richard L]

Jon,

This is because a checkvalve does not stop dribble. If the methanol is allowed to contact the hot exhaust gas during the exhaust stroke, you will most probably create a good environment of pre-ignition. Use an inline to ensure there is no change of dribble. (keep the line to the jet as short as possible.

A number of checkvalves can be used in conjunction with the inline valve to stop liquid commuting between the jets on each runner.