Hey. Just wanted to pingpong around some ideas, again. My BRAT running an EA71, more often than not, will backfire when turned off. And just recently, after the car turns off, it actually cycled the engine (after it had been sitting) a few times. That scared the crap out of me when it happened.
So, obviously there's unburnt fuel. My question is, is it likely in the cylinders, or worse, would it be in the exhaust and the backpressure caused the engine to cycle through the exhaust valves? Doesn't sound likely, but then again this vehicle's been really odd to me.
Before, I wasn't able to get it started. This seemed to be attributed to tight valves. I adjusted the lash and she fired right up. Since then I've also slapped a new fuel filter in, and I adjusted the carberuator. It's running a dual-carb weber, and it is still idling very high. I have the idling screw backed out as far out as it will go (not touching the arm), and still my idle is close to 1300.
Doing some internet searching, some people are also suggesting that this scenario might also be caused from a lean condition in the engine? Fuel doesn't ignite in the cylinder, passes to the exhaust, when car shuts off exhaust creates a vaccuum, inducing air and then red-hot exhaust components causes the ignition of fuel. So I'm confused, and wanting to see if anyone has any idea. Rich or Lean? Or Leak?
Thanks in advance.