Login  Register

Re: 79 CB750 spark question and engine miss at speeds.

Posted by LukeM on Aug 06, 2014; 7:05pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/79-CB750-spark-question-and-engine-miss-at-speeds-tp4052433p4052934.html

FYI, what is happening with the electrical tape on the pod filters, is restricting the airflow on the input of the carb.  The factory airbox does the same thing by design. That restriction is the "vacuum" if you will that the carbs are looking for, for normal operation.  Naturally, there is a balance point between how much tape covers the filter vs. how much the carb needs to work properly, vs. how much air is getting to/through the carbs.

Without the tape, there is less restriction, hence less perceived "vacuum" at the input, hence the carb(s) freaking out because that "vacuum" isn't there.

Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.