Harley M8 crank trigger information needed

[riverc4c]

Hello all,
    I have an M8 engine that I will be tearing down in a few months and because I haven't been able to see the internals, was wondering if anyone had the trigger information. I'm kind of planning ahead and won't be using a plug and play ECU for the tuning aspect. Was wondering if anyone had the crank sensor type (VR or Hall) and the amount of teeth the crank has with the type of edge (falling or rising). Tried searching everywhere and couldn't come up with the info. Thanks in advance.

[rigidthumper]

Hall cell, triggers on falling edge, 32 teeth with the tooth at the crank pin missing.

[riverc4c]

Hall cell, triggers on falling edge, 32 teeth with the tooth at the crank pin missing.

I appreciate the info. Thank you very much.

[FSG]

not looked at a M8 but below is for a TC

remember it's a 4-stroke engine which means there are 2 full crank rotations

the gap, 2 teeth missing, is a reference point so that the ECU/ECM knows where #1 TDC is

but it doesn't know if it's the intake stroke or the exhaust stroke

to determine that it uses the rotational speed of the crank (crank position signal), if it's slowing then it due to compression, therefore fire #1 plug

one of these days (!) I plan to use a storage scope and record the CKP Signal with and without plugs installed




P.S.  I did use a storage scope and record the CKP Signal with and without plugs installed BUT sadly have misplaced it   

[Ohio HD]

I'm pretty sure this is TC only, but it may give some insight to the way the ECM gets the data. Depending on what tuning software, etc., some of the values may be skewed slightly when the tune is completed.

I believe this was made by Joe Lyons. 

[hrdtail78]

TC' and M8's are different.  Notice the CPS is in a different place.  I would use a degree wheel and then verify with timing light.  I'll give the hint that whatever degree you do use.  Needs to be a derivative of 11.25.

Don't know the ECU you plan on using, but the ones I deal with allow either MAP sensor to determine which cycle the engine is on or slowing of crank.  MAP is easier to set up but doesn't always do the best job with huge cams and the problem they can cause with poor vacuum at idle.  I prefer the slowing of the crank method, but it is harder to set up because it needs to know where to look for the slowing of the crank.  So, one needs to determine when the ECU should look for this slowing in degrees of rotation.

[rigidthumper]

I believe the M8 crank looks more like this.

[rigidthumper]

This is a TC CPS signal.

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[hrdtail78]

I believe the M8 crank looks more like this.

Kind of but the crank pin is in line with the 32d tooth.  Or where that tooth would be.

[hrdtail78]

I'm pretty sure this is TC only, but it may give some insight to the way the ECM gets the data. Depending on what tuning software, etc., some of the values may be skewed slightly when the tune is completed.
 

Chart seems 11.25 off to me.  Tooth number one is not 11.25.  The leading edge of tooth one is zero which makes the leading edge of tooth number 2 11.25 degrees past leading of 1.  This mean the leading edge of the 6th tooth is actually 56.25.  The 6th tooth leading edge is the tooth lined up while rear piston is at top dead center and how the ECU knows crank position.

BTW This is all been proven by me with a degree wheel, timing light and national championship bikes that hold records.  I have 6 TC's running on stand alone's and an M8.  For those that follow my social media.  Pics and videos were posted some time ago. Do you want me to give the degree's and tooth counts for the m8 also?  180 degrees after tdc of rear.  The number 1 tooth leading edge is at CPS.  (Why the pin is inline with 32 missing tooth.  If pins were not lined up with a tooth.  11.25 wouldn't be a magic number and it goes into 180 evenly.)

[Ohio HD]

I'm pretty sure this is TC only, but it may give some insight to the way the ECM gets the data. Depending on what tuning software, etc., some of the values may be skewed slightly when the tune is completed.
 

Chart seems 11.25 off to me.  Tooth number one is not 11.25.  The leading edge of tooth one is zero which makes the leading edge of tooth number 2 11.25 degrees past leading of 1.  This mean the leading edge of the 6th tooth is actually 56.25.  The 6th tooth leading edge is the tooth lined up while rear piston is at top dead center and how the ECU knows crank position.

BTW This is all been proven by me with a degree wheel, timing light and national championship bikes that hold records.  I have 6 TC's running on stand alone's and an M8.  For those that follow my social media.  Pics and videos were posted some time ago. Do you want me to give the degree's and tooth counts for the m8 also?  180 degrees after tdc of rear.  The number 1 tooth leading edge is at CPS.  (Why the pin is inline with 32 missing tooth.  If pins were not lined up with a tooth.  11.25 wouldn't be a magic number and it goes into 180 evenly.)

I would believe that you're right regarding the actual tooth number designation where a CPS reading occurs. I guess when this chart was made that the first tooth was just called out as 1.

[Ohio HD]

I had forgotten about this post. Some really good info there as well.


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