Topic: Pamco E advance for CB's?

[jamesbekman]

Hi Everyone,

Is Pamco pete also making his E-Advancer kit for our CB SOHC's like he is for the Yamaha xs650's?  and Honda twins? 

-James

[Maurice]

I asked him some time ago and he is not.

Would be great, though...

[jamesbekman]

Agreed

[pamcopete]

We originally made the E-Advancer for cam based ignition systems as the mechanical advancer takes a real beating from the oscillating action of the cam. As the cam starts to open the valves, it slows down (more chain tension) then as it starts on the back side lobe ramp to close the valve, it speeds up (chain slackens). The result is a constant oscillation of the cam which then impacts on the mechanical advancer, mostly it wears out the pins that hold the weights, resulting in a very sloppy advance curve, messy idle and poor initial acceleration. It had to go.

However, the crank on the CB750 and other crank based ignitions does not have this same oscillating action. The inertia of the flywheel on the crank smooths out the power pulses, so there is much less wear and tear on the crank mounted mechanical advancer. Hence, we did not think there was much advantage to making an E-Advancer for the CB750.

[jamesbekman]

Thanks for the info Pete!  Makes sense and I guess I was looking for something a little more programable instead of what you are providing which is rock solid reliability by removing a weak link.

Im not sure if you are familiar with the Megajolt system for cars, Ive installed one on an MGB and you can program your advance.

Im just always looking for something else to tinker with and being able to program your advance curve into your motorcycle with the ease of your computer (for some) instead of using different weighted springs etc is always a super cool idea to me and more precise with actually gains and rock solid performace.  I know these engines run great but its always fun to see just how great you can have one be with technology that wasnt around for Honda back then and it seems your platform you created is a good starting point to explore those possibilities.  Or maybe be able to tie into a DIY system like the megajolt.

[pamcopete]

Jamesbekman,

Well, lacking a means of knowing what the load on the engine is, such as a vacuum sensor, you really can't do much with the advance past its mechanical full advance position without risking engine damage. The engine spends most of its time at or above maximum advance, so a programmable curve would be of little use. What we did do, however, with the E-Advancer was to retard the timing below 200 RPM for easier starting and less kick back when kick starting. In the case of the CB450 twin, we also started the advance at 1,300 RPM whereas the stock advance did not start until 2,000 RPM and that did make a difference for initial acceleration.

[jamesbekman]

Thanks Pete.

That is why I brought up the megajolt system.  There is a map sensor to measure out the vacuum pressure, which could be fitted (drilled and tapped) into one of the intake ports.

Cheers,

James

[jackseattle]

Check out Probe Engineering.  Their ignition systems use an electronic advancer and have you remove the stock mechanical advancer.  Last time I checked their site they made electronic ignition systems for the smaller sohc4s and the twins.