Could someone with a shop manual for a 650 tell me which wire that goes into the cdi box is for the speed sensor?
R.

 

looks like both the pink and the black/yellow go to the cdi

 

Ok guys I'm going out on a limb here so no bashing.I figure this is what these fourms are all about so I need your help on this.
We are all aware that Kawi's cdi retards the timing after approx. 50mph. I would asume this is done by way of varing current flow from the speed senser to the cdi box ie. the higher the speed the higher the flow of current to the cdi which would then begin retarding the timing after 50mph. If this is the case if the quad was put on a stand and the amount of current flow to the cdi was monitored from the speed sensor wire at 45 or 50mph then recorded. Then you would be able to put an in-line resistor on so that the current flow to the cdi would never exceed that of 50mph. therefor the timing would not begin retarding no mater how fast you were going.
Well I need some opinions on this if you would. I build houses for a living not atv's so be kind.
Besides it beats bashing Rincon all week doesn't it???
R.

 

No you can't do that. Those things are programmed on an advance per RPM basis. They call it spark mapping, and they are usually set per some multiple of rpm, like every 1000, or 500. Some I have worked on can have the intervals changed to whatever you want. They interpolate spark advance between the RPM points. They also have some way of rpm limiting. Some kill spark, some retard timing. They do even more stuff on injected cars.

The cdi gets the RPM from the magnetic pickup near the alternator. That is how it knows when to spark. You can't mess. If you took enough electronics courses, you could make your own in a few hours, pick your curves. That is beyond me.

I think what people are talking about is that the retard occurs at the RPM that occur at 50mph and above, not that the cdi uses the vehicle speed to actually decide to slow you down. You are basically power limited above certain RPM's

I think other ATV manufacturers may think Kawi is silly for wasting so much weight on a 2 cylinder. Although, the v-twin is selling the machine, a 1 cylinder can easily produce the horsepower that the 650 puts out and do it with less weight.

However, if two identical sized engines are properly tuned, a 4 valve one cyl and an 8 valve 2 cyl, the 2 cylinder should be able to easily out power and out torque the one banger by a wide margin.

Anyone that thinks they can get even close to same horsepower out of a DS650 as the 650v-twin at equivalent tuning has had too much to drink. A two cylnder will easily spank it. Not a stock 650, an equivalently cammed, CDI, ported, carbed, exhausted 650 will easily eat any one cylinder (RPMS and displacement being equal, with no silly detuning).

 

Oshawa, If you really what to try this you would have to build a circuit. It is not a varying current signal but a clocked pulse signal from the sensor that NYROC mentioned that lets the ignitor calculate current RPM's of the engine based on counting these clock pulses or the time between pulses depending on how it's done. A basic circuit could use these pulses to charge a capacitor. The faster the pulse train is, the higher the capacitor voltage would reach (because it will also discharge some in between pulses). When it reached the level corresponding to 5000RPM or so, the circuit could switch the ignitors connection from the real sensor to an oscillator on the circuit fixed at a frequency representing 5000RPM or wherever it is before it retards. Then at least the timing would not retard. I have thought about trying this but it is nothing compared to a new CDI unit that has been properly mapped out by someone (1Bearman). That way, you will get the right amount of advance when it is needed. I am waiting like everyone else for the real thing.

 

I hate to be a be a naysayer, but that idea would create a rev limiter, since the mag pickup tells the cdi exactly where the crank is.

If you fake it out with any kind of artificial signal, you won't get spark anywhere near 28-33degrees before TDC like you want. You would not even have a running motor.

If you had more pickups (out of plane) some more advanced than others, you might be able to switch between them at higher rpms.

There is a kit to build your own CDI out on the NET, but it is madke for a specific motorcycle. If you were gonna get fancy, the CDI would not be that hard to do with some electrical knowledge.

I can wait for DiamondG. He will probably get a better product to us before I could ever figure something out. Plus, I would probably break stuff in the process.

 

If I knew how bad the CDI was when I got my machine (aug 29 2001), and I knew that DiamondG was gonna wait clear until december this year to sell one, I would have started out on a crash course in CDI building, or maybe purchase the programmable one from haltech.

 

That is right. I see no way around the cdi unless you take over control using the real sensor trigger. If it triggers at TDC. They must delay the fire pulse for 330 degress or so to fire at the right time. They must calculate the RPMs and change the fire delay to match the crank rotational speed and then change the delay for varying degrees of advance also. How do they know when TDC is the end of compression not exhaust stroke? At 6000RPM or 100RPS this delay would be around 9.17 milliseconds with each degree of advance change equal to around 27.8 microseconds. I see no way of doing this level of precision without using a microcontroller. It would read the RPM's and calculate the proper delay required from the TDC pulse to the time to fire based on both the RPM's and the advance map you would have to pre-program as a lookup table. I have done this timing stuff before, but not for engine control. I do not know anything about advance mapping on engines. Without a dyno, how would you know what is right anyway. It would be a neat thing to try though. You could copy the original advance curve up to the retarding point, but then I don't know how far you can advance. I also don't know how to rev limit? Do they simply cut out the firing over a certain RPM, or every other cycle, or retard the timing? You can hear it work in reverse. It doesn't sound like it completely shuts off. I could simulate everything on the bench before hooking up to the machine. This might be worth doing if we have no alternative. You could see the current advance rate and reverse limiter stuff with an oscilliscope. Sounds like an interesting project. Usually this kind of stuff is not worth the time and cost unless you are a business. The unit from 1Bearman will be well worth the money just for their expertise and extensive testing!

 

As a rule of thumb, I always started off with 10 degrees per thousand rpm, stopping at 32 degrees, 3200 rpm. then I would use the dyno to find the right timing. I never tuned anything with small cylinders like the 650, so that may be a little too advanced.

I don't have access to free dyno anymore.

 

NYROC, tell me about this "cdi build kit" you saw and how much are the Haltech ignition only units?