My new speedster doesn't appear to be getting fire to #3 and #4 cylinders. When I ground the plug wires to the head with a screwdriver I get good spark from all 4 plug wires, but there's no discernable difference in engine rpm when I ground 3 or 4. Both 1 and 2 show marked rpm reduction when I ground them. Upon removing the plugs 3 and 4 look as though there's no combustion taking place--squeaky clean. I've swapped plugs from 3 and 4 to 1 and 2--3 without any change in result. I've changed plug wires. I'm running new Champion X's, but the result is the same with new Champion 25's.
Any suggestions appreciated. Thanks.
The coil box is the root of all evil, Try swamping the coils around and see what happens
Do a compression test.
Frank nailed it. According to your post you ARE getting fire to 3 & 4. Do a compression test- should be around 55 PSI. If not pull the head and I'll bet you find trouble with the valves...
Could be the head gasket. One very common place for a gasket to blow is between two cylinders. Either between 1 and 2 or 3 and 4. The gasket is very thin in that location and you would lose compression in both cylinders if that were to happen.
Thanks. Will report back.
It was a defective gland ring in the rear intake port. Thanks to everyone for your help.