Microsquirt v3 ignition timing

[TimoL]

I'm having problems with setting the ignition timing for Microsquirt v3.

The hardware & software setup is:

1 cylinder 4 stroke 650 cc engine. (Honda NX650).
I have been using the uS for fuel only with success.
I'm using the stock pulse coil (VRS) signal as trigger input (1 tooth at crankshaft, 1 pulse per engine revolution).
The same signal is used by the stock CDI ignition system.
µS FW version is Extra 3.4.2.

I have been testing the ignition timing by running the motor with stock ignition system and having
the µS control a LS2 coil with a spark plug connected & grounded to engine block.

According to the bike's service manual the stock ignition advance should the be at full 28 deg BTDC past 4k rpm, which I have verified using the timing lamp.
The timing has very little jitter with the stock ignition and is spot on at 28 degrees.

I've tried anything between 80 to -40 degrees trigger offset (should be around 10 deg BTDC, I believe) and Rising & Falling Edge capture,
but I cannot see the timing mark though the timing inspection hole when connecting the timing lamp to µS controlled spark plug wire while the timing being locked at 28 deg BTDC.
The µS controlled spark seems steady (actually more steady than stock ignition's) but I cannot get the timing right.
From what I gather, the problem is either too jumpy ignition timing or wrong ignition settings.

The attached files are the current tune, composite log and tooth log.
The logs have been captured when starting the engine & running it at about 4k rpm for a few seconds.
I have already looked at the logs and the tach input looks steady (except while cranking, but that's another story).

I'm a bit stuck as of now and any help would be greatly appreciated.

[hybrid]

Why don't you verify where the tooth actually is with a degree wheel?

[TimoL]

Why don't you verify where the tooth actually is with a degree wheel?

I was hoping to avoid that because pulse coil is located inside the clutch cover, so I'd have to open open both sides of the engine.
And the engine block has oil passages to the flywheel "chamber" so I can't run the engine with the cover off.
But I guess verifying the timing manually is the next step.

[hybrid]

Fair enough. It's just hard for anyone to help unless they know that engine.

Sent from my A0001 using Tapatalk

[TimoL]

I just finished opening the engine to take a look at the pulse coil.
The timing base advance is indeed 10 deg BTDC. I noticed the trigger tooth is quite long, approximately 2 to 3 times the length of the pulse coil tip.

Honda_NX650_pulseCoilAndTooth.jpg

I remember reading about the long tooth causing some problems with the MS2 ignition timing. Could this be the issue?
The rpm reading is quite stable and the fuel only install has been working nicely so far so I doubt the trigger pulse is bad?
I also attached the µS ignition output an old oscilloscope and the time between ignition pulses didn't seem to vary much when holding steady rpms.
But I suspect the timing jitter could still too much to see the timing marks on the flywheel with the timing lamp?

If the long tooth really is the issue I could grind it down but if it doesn't work I could end up with no working ignition.

[TimoL]

Update:

I have managed to get the engine running and the ignition timing is quite stable above idle.
Apparently I had no idea what I was doing when setting the trigger offset ( ).
Through trial % error I found the correct angle to be at 40 deg BTDC.
I also smoothed the trigger tooth and made a little shorter (in the direction of travel) to allow a sharper zero crossing.

Overall the bike runs really good, better than with the stock CDI ignition. The hard part is the starting.
I even bought a new battery, but sometimes I can't get the engine to start before the battery goes out of charge.
It's a bit random since sometimes it fires right away and actually idles, even when the engine is cold.

It looks the ECU loses sync while cranking but never when the engine is running.
I have swapped the cables to shielded ones, routed them away from the starter and grounded everything at the engine block in case the problem is due to starter noise. But none this has helped at all.

I'm planning on fabricating a 11-1 crank wheel(11 teeth because the ""template part" has 22 splines, so the teeth are easy to line up).
I suppose 11 teeth wheel is possible for 1-cylinder?
By the way: Does anyone know the optimum missing tooth angle for single cylinder engine?

[racingmini_mtl]

I suppose 11 teeth wheel is possible for 1-cylinder?

No. You need a number of teeth that will give an integer number of tenths of degrees for each tooth interval. With 11 teeth that's 32.7272 degree per interval which doesn't work. You need 10 or 12.

Jean

[TimoL]

I suppose 11 teeth wheel is possible for 1-cylinder?

No. You need a number of teeth that will give an integer number of tenths of degrees for each tooth interval. With 11 teeth that's 32.7272 degree per interval which doesn't work. You need 10 or 12.

Jean

Oh, I see, how could have I missed that...
Thanks for correcting me on this. Probably saved a couple of wasted working hours.
I guess I'll to have do it the hard way and make a 16 teeth wheel (22,5 deg/tooth).
Any suggestions on the missing tooth angle?

[TimoL]

In case info it benefits anyone, here is what I've done during winter:

I ordered a 2" 36-1 trigger wheel and installed it to the end of the crankshaft.
The tooth width for this wheel was a perfect match for the OEM pickup coil.

The trigger wheel made starting a little easier. It still had some sync errors.
After a couple of weeks I had the starter clutch fail totally, the starter would not engage anymore and just spun freely.

I replaced the starter clutch with a one that had less miles on it, and bike starts just like it did with the carb & stock ignition, if not even better.
I believe that the faulty starter clutch kinda slipped just before TDC, causing the engine spin backwards a little which would lead a sync loss because of extra teeth seen by the µS.

I will post the full setup of this build in the Success stories section after I'll get everything sorted.