Surging

Trailbeast, I've had times when I thought backfire was fuel related, but there's really no reason for fuel to ignite before the intake valve is closed. So it pretty much always has to be timing related.

Well that's a nice thought anyway.

A little demeaning on the remarks about people trying to help another member regurgitating nonsense.
It doesn't come across very well, just so you know.:D