I recently purchased a café rebuild of a '74 750. I am having a hard time getting the air/fuel mixture right and hoping someone can help me.
I have the stock airbox but a cycleX 4-into-2 exhaust system and an electronic ignition installed. For Jets, I have 110's in there now, which has undoubtedly been an improvement from the 120's I had before. Although, the plugs are still quite dark, and they foul after roughly an hour of riding. I think the next change is to lift the slide valve.
The main thing I don't understand, is why the right-side exhaust (cylinders 1&2) is popping? The left-side pipe doesn't pop, yet the plugs still indicate that its running rich. If the right side were popping and cylinders 3&4's plugs were okay, I would think the answer might be head gasket seals, but considering it is all of the plugs I don't know why that would be the case. Any ideas?
