BannedCR500Riders.com

well I did a searching and found a guy that cut one open and guess what its a capacitor-resistor like I said above.

here is a copy of the post:

MotoBikeMike07-08-2005, 07:16 AM
I havent done anything to mine yet. It will certainly become an experimental subject at some point. Years ago I tried a Answer Roost Boost (Anyone remember those) on another XR. We cut one open and if I remember correctly it had a total of two components (A resister and a capacitor). When we looked at it on a scope it slightly altered the timing curve. Seat of the pants reality was that you could actually feel a change for the better but it was very subtle. You had to very familiar with you machine to feel the change. We have to be careful to keep if safe but given the capability to make slightly larger timing changes could bring better results. Especially at higher altitudes. We are way early into this project though, and have a lot of experimenting to do.


Mike


so if you look at my pictures you can see how the current will lead the voltage in a capacitive circuit and if you add a resistor it can be fine tuned to the amount of lead you want.

remember the flow of electricity is represented by current not voltage

and like I mentioned before I have tested this by putting a timeing light on the motor and it showed about 2 degrees of advance.

Now I have never endorsed the use of roost boost just explained what it does.

my theory is why use a electrical piece to advance the timing when I can adjust the stator

And I will be rounding up another roost boost that I handed down to a nephew to do some more testing but this may take awhile before I can post because I need a part for my bench tester.

And no I am no video taping the test because I dont have a recorder so if someone that lives in chicagoland area wants to come over and see "time-travel" in person you will be more than welcome!

Rss wrote:my theory is why use a electrical piece to advance the timing when I can adjust the stator

You are not "advancing" the stator.You are reindexing the stator plate to retard the position of the pulse generator in relation to the crankshaft (which advances the timing)


To my memory, the Roost Boost goes between the stator and the CDI.

The "Pulse Generator " picks up to timing tab on the flywheel and triggers the CDI to fire the plug.

So how does the "time advanced" A/C voltage from the Roost Boost influence the D/C signal from the CDI to the coil?

Is it telepathic or something?

Is it telepathic or something?

no no no, your looking at it the wrong way, its just magic

The theory that it retards the timing so much as to cause an advance is probable, but that would only work while the engine is running at a decent speed.

Think of this:

You kick the bike once and the flywheel triggers the pick up once (triggering the Roost Boost to do its huge retard of the timing) but the bike doesnt light off. How does the device know when to spark on the second kick?

Without a crank wheel like a modern motor has, with HUNDREDS of notches on it and read by a traditional hall-effect trigger, this device would be very unreliable. It would require an IC that didnt activate the retard (resulting in advance) until the motor was known to be "running". You would need an oil pressure switch (4 stroke) or a crank trigger wheel in order to make that work. All of which is waaaayyy more involved than simply changing the timing advance like the manual tells you too (2 bolts and a timing light).

Rss wrote:
my theory is why use a electrical piece to advance the timing when I can adjust the stator


You are not "advancing" the stator.You are reindexing the stator plate to retard the position of the pulse generator in relation to the crankshaft (which advances the timing)



I think you need to reread what I wrote







To my memory, the Roost Boost goes between the stator and the CDI.

The "Pulse Generator " picks up to timing tab on the flywheel and triggers the CDI to fire the plug.



Your memory has failed you, sorry but it is wired into the pulse generator circuit.






So how does the "time advanced" A/C voltage from the Roost Boost influence the D/C signal from the CDI to the coil?


Definition of a Pulse generator:

A pulse generator consisting of a stator with a permanent magnet and a rotor, which induces an AC voltage in the inductive winding by the periodical change of the air gap between stator and rotor


I will admit that the sine waves that I posted are not correctly shaped for a pulse generator
I was not able to find the proper pictures, but the pictures pointed out the phase shift that happens ,which no matter what shape the pulse is, the phase shift still applies.



So now that I have answered your sarcastic post that does nothing for learning I will let you know I have tested and disassembled a roost boost that I once owned and tested that showed advanced in ignition timing.

It turns out that at least on the later model "Roost Boost Plus" boxes it consists of a simple resistor that is shorted between both leads of the pulse generator circuit.

Now at first glance this may seam like it would do nothing but in fact its a pretty good way manipulate the pulse signal.

since the pickup coil will have a certain amount of inductance the current will lag voltage.
As rpms increase the effect gets more and more pronounced, meaning a larger phase shift between voltage and current.
The is referred to as Inductive Reactance

Honda was well aware of this and adjusted the timing curve accordingly.

So what does the resistor do then?
Well if you want to knock the inductive reactance down, just increase the "load" on the circuit, this in return will move current phase angle closer to the voltage phase angle.

Think of load as a light bulb being added to the circuit.

By moving the current phase closer to the voltage phase you are advancing the pulse signal from what Honda anticipated it to be, thus advancing ignition timing.

So the magic question you are all thinking is why would Honda not have done this, well I will venture to say they felt they had enough "load" in the circuit and designed the ignition timing map around it.

It doesn't mean this added resistor made the circuit any better than before, it just changed it.
Which in this manner slightly advanced the ignition timing giving you a "Boost in your tire Roost"

M.F.D.B. wrote:The theory that it retards the timing so much as to cause an advance is probable, but that would only work while the engine is running at a decent speed.

and you would also need computer shit to calculate when to deliver the spark.....which a Roost Boost is NOT