550's?

[Steve]

Suzuki changed the cam timing on the 850 when they added the cross over chamber in the exhaust. I think the later cams are tuned for more bottom end power compared to the early cams. If using a 4:1 exhaust and pods, I would think the early cams would have an advantage at high rpm.

Not sure if they changed the cams because of the crossover pipe or it's just coincidence that they happened at the same time.

But yes, the timing changed from '79 to '80. The duration stayed the same, but the timing was advanced 10 degrees, so they open and close 10 degrees earlier. Earlier intake valve closing is better for low rpm torque.

.

[nisom512]

Not sure if they changed the cams because of the crossover pipe or it's just coincidence that they happened at the same time.

But yes, the timing changed from '79 to '80. The duration stayed the same, but the timing was advanced 10 degrees, so they open and close 10 degrees earlier. Earlier intake valve closing is better for low rpm torque.

.

ok while I am still trying to understand timing I have a question for you steve on your 81 850 does it have a 2+2 exhaust or does it have and H pipe on it connecting them?