Need opinions to fix a missing tooth issue

[gboezio]

The motor is a single cylinder 4 stroke honda 450 motor, the first setup I ran was a 8 tooth and cam sensor setup.
Due to the cam beeing all over the place I have machined another trigger wheel at 16-1 plus single tooth cam sensor.
I could rev all the way up without sync loss, but it failed me at the track.
As I passed 7200+ and decelerating between 7200 and 6800 I had sync losses and 1 time on 3 the engine would cut out completely until I came to a stop, then it was flooded.
I cleared flood and cranked and it got back to life, so I have finished the race below 6000 rpm and it went quite well.
The engine crank and tranny are separated by a straight cut gear that have some backlash, I think I'm hitting a resonant frequency and the crank will decelarate and reaccelerate quickly.
I realised that I have placed tooth # 1 120 deg ATDC instead of BTDC and I was to fix it, but looking at the tooth log I don't think it will fix my problem.

Possible solution : placing tooth missing tooth exactly at TDC so it stands on the top of the longest tooth and be super long ?? Can the long tooths close to TDC be ignored ??

Problem reveals itself at page 13 on the tooth log

[Drew442]

I went through all this with a crank triggered Honda single. The issue ended up being that the Honda VR sensor was grounded to case. Have you checked this?

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[gboezio]

Thanks, for the reply, how this has affected your tooth logs, false pulses ??
I can count all my trigger and they are all there, but I could not reproduce what happened at the track on the garage, except the low speed log I have posted
I will go back to make another tonight, I will check if the pulse gen out conduct to ground.
I was thinking to rotate the ring to 120 deg BTDC and cut a second tooth to increase the gap, the VR sensor seem to be very stable, highest noise I could find was about 2,5 V most is below 0,5V (pots are fully closed CCW)

[gboezio]

After countless pulls I could catch it on a tooth log, ended up to be a missed pulse and not a resonant frequency, I'm all ears to learn how you have fixed this issue !!
Still happens on decel and even if the RPM is back up it will still die all the way to 0 rpm, maybe it's flooded, not sure why, unless MS holds fire.
I'm a bit lost here

Missed pulse twice on Page 28
MSQ attached in case

[Drew442]

I don't recall the tooth log output now. It was too long ago. I probably posted it on this forum though...

Did you check your VR sensor continuity to ground?

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[gboezio]

I measure infinite resistance between both poles and engine block.
The signal looks clean on the scope, but I can't catch the problem due to my scope beeing very slow

[gboezio]

Things I know, it happens only and only on decel,
on tooth log a trigger is missing,
there is an occurence of twice the rpm before sync loss, sometimes the engine keep running,
sometime it feels like ms is freezing and coast like an ignition cut, then engine is flooded, sometimes the datalog hangs at a rpm while the engine is at 0, other data seem ok

What can happen on deceleration that can cause this, I'm baffled.

Not sure if ms freeze or I'm chasing a real sync loss issue

[Drew442]

What hardware are you running?

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[gboezio]

MS3 3.0 DIY, Logic spark, ICV, LS2 Coil.

Thanks for the help, but I have finally found the problem.
I used the stator that was in the engine before.
I have left the 3 wires disconnected but the coils were still there and floating 80 to 130VAC.
No big deal right, even with the wires riding along the VR sensor wires and the 3 stator poles on the stock wiring package.
But things went to hell when the stator shorted to the armature, discharging the common wire of the two coils, turning the wires in nasty antennas.
And I could remember the huge farts from my exhaust over decel last year when I blew the stator (exciter coils)

To make things worse, I'm pretty sure I had my trigger reversed, I was using falling edge while my scope because trigger will be from positive to negative, but I forgot that the VR conditionner had a reversed output, but it ran but it shouldn't.
I remembered that it wasn't a mistake to put tooth#1 120deg ATDC, I did this on purpose, it seem to be the best window to put tooth #1, but now I use 165 deg ATDC with a 16-2 wheel. The 120 BTDC position was the most horrible of all, the closing intake will spin the crank and delete the long tooth, 80 BTDC did not work too.
I wish I had a velcro flywheel, I have yanked it out about 6 times and even panicked and put it back where it was when it ran, but guess what, it wouldn't run !! At that time the exciter coils were both removed, so maybe the RF did do something since it was the only change at the time except a 5 deg offset of the wheel.

So I have started cursing all the saints and pulling hairs all triggers were there, but the compression would throw the motor out of sync every time the decompressor closed so the engine would fire up but not run, then I have cut a second tooth and advanced the tooth #1 45 deg on a most stable aera on both strokes, same no go !! After splitting open my cranium on my toolbox and have somewhat calmed down or ran out of tools to throw. I have finally counted the triggers to discover that even though the problem remains, it has changed.
I'm having extra pulses, so I have trimmed the pots to get rid of the false trigger and bam it started right up !!
But as expected, the rigning of the VR sensor on the huge hole forced up the trigger up, so the timing started wandering up to 2,5 deg, I have used the spark trim table to bring it back dead straight, now it fires up and wont loose sync unless I hit the throttle stupid fast, I have pulled some timing on the upper left of the table, I should be able to be stupid now.


On a side note I have raced the quad below 5k rpm and the incredible smoothness and torque of timing I pulled at low RPM makes it worth the whole effort by itself, it will be cake if I can get a whole lot of power out of it !!!
I hope this helps the single cylinders squirters !!