Hi all, I've recently picked up a '80 KZ650 LTD and have been trying to work the kinks out. I've found a wealth of information in the forum here, thank you. However, I'm having trouble with popping and backfiring out the 2-3 exhaust. Either 2 or 3 seems to be running rich because gas sometimes drips out from around a bolt on the underside of the 2-3 exhaust where it connects to the muffler. I guess that means I have a hole in the exhaust, huh? I'm assuming #2 is rich because that plug gets carbon fouled and the others don't.I have VM24SS carbs with the accelerator pump.
Here's what I've done so far:
-Checked valve clearances (within spec)
-Installed Dyna S ignition and green Dyna coils
-Did the WG coil relay mod
-Set timing (and double checked a couple times)
-Removed carbs and verified they were clean
-Mechanically synchronized carbs
-Fine synchronized carbs
-Checked float levels by the wet method (within spec)
-Air screws 1.5 turns out
Now, any recommendations on what I should try next? I'm probably too rich on #2 and getting oxygen in through the leaky exhaust, hence the backfiring. Any thoughts on how I can cure the richness problem? I was thinking it might be the accelerator pump diaphram because it's on the #2 carb. Or... I found that the accelerator pump ball bearing check valve in the bowl of the #4 carb is missing. Could this be causing problems? Help! I'm running out of ideas