Minimum rpm needed to activate spark

[Whitbread]

Tried searching around, but didn't find much. Anyways, hopefully this will be a very quick question for someone.

I'm planning on using microsquirt to efi my Yamaha banshee. For those not familiar with it, it's a kick start only, two stroke, in line, twin cylinder boxer. It uses 2 lugs 180* apart on the flywheel and a vr sensor to trigger the wasted spark cdi ignition. I have the fueling side of things all figured out but I've been getting conflicting answers on the ignition. I would like to use MS to run the ignition also but I've been told that MS will not fire on anything less than 50rpm's for 3 revolutions. So I was told that becuase of this, I would never be able to kick start the bike again. Is this correct or was this only a quirk in older units that has since been fixed in Microsquirt?

[grippo]

It is correct - the min rpm is 50. doesn't have to be for 3 ignition events - it can be for 2, maybe 1. But I know some people have gotten round this - can't remember how.

[Whitbread]

Thanks for clarifying that! The gentlemen that passed me the info had said he already tried using a mini ms to run spark on his banshee and said he couldn't get it working. Don't know how long ago that was or if everything was even mapped properly.

Since it has 2 ignition events per flywheel revolution, a good kick should produce at bare minimum 1-2 revolutions above 50rpm. Does that sound like a plausible senario for MS to work without any vodoo? If the rpms drop below 50, but things are still moving, will MS keep the ignition active or will it kill it?

I'll try to measure it the next time I can get ahold of an optical tach.

[grippo]

It will kill drop synch if it goes below 50 rpm. The reason for this isn't arbitrary, it has to do with the size of the computer word used to hold the timing and the resolution of the timing. You want high resolutuion at high rpm but want to also handle long time periods, so 50 rpm was a compromise. You also need an rpm that indicates stall so you can try to resynch as soon as possible.

[24c]

It is correct - the min rpm is 50. doesn't have to be for 3 ignition events ...>8

On my bench rig, my sparking stops at 257rpm if I let the crank freewheel down from a fast idle, and this is on a 4cyl, with 4 "teeth" on the crank wheel. Is it possible to get sparking occurring at lower speeds with my set up.

FWIW. I did notice the modded Thunderace crank, which has 8 "teeth" and it did spark at lower rpms. The tacho in TS started from about 120+ rpms, so I thought it was related to the number of teeth.

[grippo]

As best I remember I have run single cylinder at 60 rpm on the bench. You should be able to reach that regardless of no. teeth. If you send me your bench msq I will test it, but I won't be able tp get to it til middle of next week.

[24c]

Al thanks for the offer, because it got me thinking... in all my fiddling maybe I had done something inadvertedly.

Booted into Windows, tried to reload 2.89 failed on verification first time, then was successful second time. Got an ini mismatch, but USB driver was playing up in Windows XP, so I booted into the Mac OSX side, and used TunerStudio. This alerted me to the controller mismatch, so went with unadulterated 2.89.

Set ECU, changed the teeth set up, switched the cranking trigger tolerances, but left it as alpha, beta gamma not last interval...and now I get readings looking at the the tacho from 64 rpms upward.

EDIT, it was set on 8 cylinder by default , but still seeing sync starting at 63/64 rpms.

[24c]

Don't know if this is right place to post this, but I have been experimenting with the crankshaft rig for a couple of days, playing with a VR conditioner to try and improve my VR2+ cam sensor signal, in an attempt to lower the rpm to activate sparking. Stock ECU is fine, but the MicroSquirt struggles to see the VR2+ input, and doesn't sync.

Introducing a VR conditioner created more problems than it solved (increased resets), but the rpms that sparking starts at, in my application a Yamaha GTS1000, is more dependant on the cam sensor air gap than anything else. Increasing the gap, increased the revs it took, so that a 1mm gap was needing 400 rpm before the system synced, and started sparking etc, which is an issue if a good battery only cranks the starter at 350.

By reducing the cam sensor air gap I got more crosstalk, but by using two small diodes I had lying around, on the paired sensor negatives, I now get stable "running" up to 1400 rpm. The last seen figure on the tacho in TunerStudio has dropped to 97rpm now, and I can hold it at 150 rpm comfortably.

PS I did try reversing polarities, resistors and capacitor variations on the sensor lines in back to back tests, but one diode in series to each shared ground worked for me. I don't know if anybody else has experienced this, but it gives me a start in getting my engine up to idle speed, and now I can look at buying a pair of MicroSquirt Module boards again.

[panheadsforlife]

This post seams to be the closest to answering the question I Have

I appears that the minimum cranking speed to get spark is 50 RPM. Is that still true with the newest version of Micro Squirt ?
using Independent Dual Ignition with one tooth on the cam using 2 hall effect sensors and 2 separate coils for a 2 cylinder engine
this line from the cranking trigger section in the instructions gave me a glimpse of hope there might be some way around this

Trigger Rise: is the best all around selection for most installations. It fires the spark plugs when the 'normal' trigger is seen (i.e., the signal that comes at the trigger offset). Use this if it you are able to set up your tach input to your MicroSquirt® controller so that it comes in at a good timing advance for starting, generally something like 5-12° BTDC. Then your MicroSquirt® controller will fire the spark at the exact instant the trigger signal comes in and you will have consistent advance during cranking (at the trigger offset), no matter how uneven the engine speed.

Please help... this entire project depends on if it will work for kick starting
Thanks

[Toymg]

I am in the research stage of this aswell exept I want to run a large bore single 2 stroke, I'm thinking about just running a flying magnet to run the coil direct for start up and then at a certain rpm have the megasquirt take over and run off my vr sensors and tone wheel, I'm not sure if this will work but it should, Any input on this from you gurus would be great because so far this is my best plan, thanks, Blaine