I hate to bust your bubble sonny, but megs and pods are not really a heavily modified bike. For all intensive purposes the internals on your bike are stock and will react like a stock bike to changes.
running advanced or retarded timing on a stock bike isn't going to really do anything for you. your stock timing is a balance of low end performance and top end. If you change the timing the bike will run slightly better at one end of the spectrum and really bad at the other.
If you had a radical cam and big bore kit this would be something you would be looking at, but for just pods (which aren't a performance mod BTW) and an exhaust I woudn't bother with it. You won;t get anything out of playing with the timing also because the biggest restriction in a cb750 is the head. Port some of those passages and maybe you can start to see an increase.
In the old days (the 90's...ha) I used to play with the timing on my GTO a lot because I ran a fairly radical cam and high compression and when I couldn't get 94+ octane I would have to retard the timing so the motor wouldn't ping.
You want some cheap performance, 78 cb750 carbs (espically F carbs). Accelerator pump carbs like on the GS and KZ and they are usually worth a good extra kick in the pants, plus smoother throttle response. you will need the rubbers off the same motor but it will make a difference. Also put your stock airbox back on and install a K&N inside.
here are hondaman's archived posts on the sohc4 board. READ THESE. And when you are done read them 2 or 3 more times. I am currently looking for his post on cheap tricks on the 750 that is worth reading too.
he does describe the differences between the different K model's ignition timing but at one point he does leave out the different cams that honda used. according to honda there is only one cb750 cam but we know this not to be true now and there were several different cam timings (different than ignition timing) for similar grinds.
Also maybe it is time you think about suspension mods too. All that power is no good if you can't find a way to get it to the ground.
Edited by - geeto67 on Aug 21 2007 4:54:05 PM