I am converting one of the racebikes to MS-II and V3 board from the original 2.2 MS. Am running the fuel portion now, and using the OEM CDI.
Have had little luck with the ignition.
The motor is a 540cc single. So the timing is very erratic, all the way up to a couple thousand RPM. Even if the motor is running smoothly, every other revolution is slow/fast so that the timing is off by +-15degrees between any two cycles.
I can raise the cranking RPM up a bit so that the cranking trigger could be edge triggered instead of calculated. This helps get going, but it also makes sure that you are in cranking mode for fuel too, so it causes trouble.
At this point I am thinking of modifying the code so that the ignition stays edge-triggered until the cycle-to-cycle effects are tamed a bit.
Are there any other ideas out there? Looking for a better way...
A "single" problem
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newtyres1
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Brent,
Well, no-one else is having a go, so I'll jump in...You say the timing is varying +/- 15 degrees, in your earlier post you said "The reluctor tab is 32 deg long" is this a clue? I find it hard to envisage a motor speeding up and slowing down 15 degrees every 2nd crank revolution, I feel the prob may be more in the reluctor pickup section than the motor speed varying, but I've been wrong before. Also it could be a dwell problem. The problem goes away over 2000rpm? How many triggers does MSII need to run a single cyl single coil?
Ian.
Well, no-one else is having a go, so I'll jump in...You say the timing is varying +/- 15 degrees, in your earlier post you said "The reluctor tab is 32 deg long" is this a clue? I find it hard to envisage a motor speeding up and slowing down 15 degrees every 2nd crank revolution, I feel the prob may be more in the reluctor pickup section than the motor speed varying, but I've been wrong before. Also it could be a dwell problem. The problem goes away over 2000rpm? How many triggers does MSII need to run a single cyl single coil?
Ian.
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BrentP
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The motor is changing rotational velocity between cycles. I have logged this on the oscilliscope. It is a high-compression roadracing single without much flywheel.
During one cycle it is pushing against a high compression 540cc cylinder, and the next it is toward the end of the exhaust stroke after getting thrown by the same cylinder. Since there are no other cylinders and not much rotational inertia, it seems to track the forces pretty close.
I removed the VR sensor at one point and put in a geartooth sensor and got the same results.
The 2kRPM is somewhat arbitrary. The stock CDI triggers off the trailing edge of the reluctor (6deg BTDC) and has zero advance from there until it gets to 2kRPM. I figured by then the cycle-by-cycle variations would be minimal, && it would have no effect on the IGN map I would be using.
Last night I tried it out with the code changes, and it started right up and idled and all was pretty happy.
Once it was running, I noticed on the scope that I was getting two triggers to the CPU from the VR circuit. One was at the leading edge and one at the trailing edge. This only happens when the bike is running and getting higher voltages from the VR sensor.
No changes to the two trimpots in the VR circuit seemed to have an effect, so I put a diode in to tame the VR sensor spike and now the VR circuit is only sending the one trigger.
It is starting to look like I will be able to race next weekend!
During one cycle it is pushing against a high compression 540cc cylinder, and the next it is toward the end of the exhaust stroke after getting thrown by the same cylinder. Since there are no other cylinders and not much rotational inertia, it seems to track the forces pretty close.
I removed the VR sensor at one point and put in a geartooth sensor and got the same results.
The 2kRPM is somewhat arbitrary. The stock CDI triggers off the trailing edge of the reluctor (6deg BTDC) and has zero advance from there until it gets to 2kRPM. I figured by then the cycle-by-cycle variations would be minimal, && it would have no effect on the IGN map I would be using.
Last night I tried it out with the code changes, and it started right up and idled and all was pretty happy.
Once it was running, I noticed on the scope that I was getting two triggers to the CPU from the VR circuit. One was at the leading edge and one at the trailing edge. This only happens when the bike is running and getting higher voltages from the VR sensor.
No changes to the two trimpots in the VR circuit seemed to have an effect, so I put a diode in to tame the VR sensor spike and now the VR circuit is only sending the one trigger.
It is starting to look like I will be able to race next weekend!