cr ingition pics please

[woodsracer144]

Can someone post a pic of their Cr ignition mounted and a close up of the pick up.

Does that pick up need to be so long? Like does it have to be a half inch or can it be three eighths? Is that what controls how long the spark is?

Thanks

[250rice]

not sure if this will help and what do yoy mean about the pick up being a half inch have a pic put its too big to post pm me with your email and ill send it to you

[woodsracer144]

moto-x-man199@hotmail.com

now for the pick up...


what does the length of it have to do with it or effect?

[250rice]

iam not sure what effect it has if its long or short let me know if you got the pics iam not sure if it sent iam not used to using windows live mail

[250rice]

well i just noticed that in the second pic you can see both of the raised pieces on the flywheel and the trx does look longer for sure probably a good quarter inch longer or maybe more than the cr one

[wilkin250r]

I can't answer this one yet, but I'm working on it. But I'll answer what I CAN, and a few things I see as possibilities. They aren't certainties, just possibilities.

Talking with other electrical gurus, I've learned that the pulse generator is looking for the TAIL edge of that pick-up. Let me describe what this most likely means, from an electrical standpoint.

As the pick-up on the flywheel approaches the pulse generator coil, it will induce a voltage spike in the pulse generator (because that's what happens when magnetic fields move across a coil of wire). So the leading edge will induce a voltage spike, and when the pick-up is leaving the pulse generator, it will induce a voltage spike the exact opposite polarity.

Let me emphasis, this is just theory.

Now, it's possible that the CDI is actually looking for a certain voltage level, so let's pretend the leading edge of the pickup induces a negative voltage spike, and the trailing edge creates a positive voltage spike (again, just theory, it might be opposite). But those voltage spikes are going to be just that, spikes. It will go from zero voltage to some peak, and then start to settle back again.

Let's take our pretend situation a little further, and assign some theoretical numbers to it. Let's pretend the leading edge creates a voltage spike of -5 volts, and the trailing edge creates a spike of +5 volts.

This is possibly where the length comes in. If you create a negative voltage spike, you might need that time for that -5 volts to settle back towards zero (like -1V or so) before the +5 volt spike hits, because you're triggering at +4 volts. If you don't give it enough time, and you create that +5V spike but you're starting too early while you're still at -3V, you're only going to get to +2V and you won't reach your +4V threshold.

Again, theoretical. I can certainly tell you this is how the components will react, you will indeed be getting a voltage spike one direction on the leading edge, and then a voltage spike the opposite direction on the trailing edge.

[Uns]

I was reading this and rolling it around in my head...

Electricity generated by a magnetic field like the pickup tab and pickup should never have a speed at which the initial triggering would result in a spike that is too low due to overlap time. The rise and fall times of that tab would only be limited by the speed of the signal through copper wire(75-90% the speed of light). There may be a point at which our ability to measure the 0 to neg 5 to 0 to pos 5 to 0 is diminished to it looking like nothing happened, but it will always have the two corrosponding spikes, negative and positive, theoretically even as the stator approached light speed! In fact, the voltage spikes induced by the magnets would increase the faster the magnet passed by, representing the same magnetic field potential(force) applied over a shorter time period, thus increasing the magnitude of the potential and reducing its period.

However, it is possible that the length of the tab is indicative of the strength of the magnetic material. It is very possible that to induce a large enough magnetic field with older magnet technology at lower RPM, the tab required more material between it's south pole and north pole than modern stators. It is also equally possible that more sensitive CDIs and pickups have been produced that reduces the amount of material required in the pickup tab. I haven't looked at any pictures, and am not sure if the tab has trended smaller the newer the stator, but I'm guessing they do, possibly because of both of these effects.

I don't think the length of the tab is for any kind of circuit settle time either. If you give a nice round 10k rpm as maximum, even if the tab was one degree in length(tiny in comparison to what it is), that would give you 1/10k minutes per revolution * 1/360 revolutions per degree = 1/60000 seconds per degree, or 16 uS per degree. Even in the late 90's/early 2000's , in digital electronic terms, this was considered slow and would be easily picked up and processed easily by a cheap 8 bit micro.

Something I am seriously starting to wonder about though, is the possibility that they are using both edges, or possibly the leading edge, to calculate the rpm, and thus the advance required of the CDI. It would make a lot of sense to design a system that would read the leading edge magnet, do the advance calculations(probably a simple LUT, where the memory addresses represent RPM and the contents at those addresses the amount of advance requested) and trigger on the back side of the magnet adding spark advance(or more likely, subtracting an amount from what would be the maximum advance).

It is equally possible that they would simply both trigger and measure RPMs from the trailing edge, taking the almost-as-good and lazier way out. In this case, the leading edge would be simply there to increase magnetic field strength to induce a larger voltage spike in the pickup at low rpm.

Of course, this CDI talk is complete conjecture and I have no idea if this is the way it works... Only that this is the way I would do it.

I think the big message to get out of this for laymen is, I would seriously avoid messing with the length of the pickup tab, unless you are ok with paper weights, or possibly worse.

[woodsracer144]

this is all has to do with getting a 02 CR to work with the 01 plate, right now at TDC the pick up is at the rear of the pick up ( if the pulse tip is like a 1/8th inch its on the final 1.8th inch or so) From my understandings the 02 is 12* advanced, how ever when i was running this set up it ran like it was delayed or firing after I reached TDC cause my EGT's were high.

I took some pics but they are on my cell phone and i havn't gotten them on my labtop yet.

[Uns]

Well, that could be a serious issue. It wouldn't matter what the timing numbers were in a 2002 CR250R motor if the flywheel key or pickup coil placement were retarded several degrees relative to the pickup coil or flywheel key on the TRX stator mount plate. It seems to me like pictures wouldn't really help in this situation, and that you really should grab a degree wheel, auto battery and a timing light, and see what you are up against.

Any comparisons to any other ignition systems, especially in photo form, aren't going to do a lot of good towards ensuring your timing is correct. Not, at least, to actually checking it.

I vaguely remember your post about the 2002, and it would be killer if you get it working. I know it would be nice to ebay the 2002 ignition for half the price of a 2001 and get a newer system to boot!

[destey]

Great reads Uns. Thank you for the in depth explanations

[265 sleeper]

There is supposed to be some hang time between the the start and stop of the spark . The spark happens a few degrees before tdc . If you take your stock flywheel with the marks f and t on it and put the stock counter balancer on with the head off look at when the flywheel pick first meets with the pulse gen then look at where the piston is at she is a good ways down she is above the exhaust port but not at tdc . then look at when the pick up on the flywheel passes the pulse gen the piston still is not at tdc .

[mx91a]

Originally posted by woodsracer144
this is all has to do with getting a 02 CR to work with the 01 plate, right now at TDC the pick up is at the rear of the pick up ( if the pulse tip is like a 1/8th inch its on the final 1.8th inch or so) From my understandings the 02 is 12* advanced, how ever when i was running this set up it ran like it was delayed or firing after I reached TDC cause my EGT's were high.

I took some pics but they are on my cell phone and i havn't gotten them on my labtop yet.

The 2001 CR flywheel pulse trigger is 12 degrees advanced with respect to the flywheel key compared to the 2002 flywheel trigger. You need to remove the woodruff key and manually advance the 2002 flywheel on the crank 12 degrees to get it to work. With the piston at TDC the trailing edge of the flywheel trigger should be close to the trailing edge of the magnetic pickup. Verify timing with a light. I'm not sure what the 2002 spec is but for the 2001 CR ignition it's 18 +- 2 degrees BTDC at 3000 RPM. The 2002 ignition shouldn't be far off from that. I'd set it a little less to be safe at first.