ET: Engine (Twin) Programmable ignition

[BigEd]

As a hater of drive cables for instruments , have to say that with the exception of machines that need to stay standard there is no way i would fit any form of mechanical tachometer or speedometer to a build . Have found a digital speedo with data logger invaluable when setting up carburation without resorting to dyno time. Just to easy to set the "gate" parameters to time the interval from 60 to 110 in third (or any of your choice) to see the effect of jetting changes.

Dear Jim,
Would you care to share the source/manufacturer of your speedo of choice with data logger.

 

[Cyborg]

What speedo do you use? Just out of curiosity..... I'm committed anyway because I have the Smiths Digital Speedo that I bought for the B Rapide, but it just didn't do it for me so I sent a absolutely disgusting looking chronometric speedo from lord know what... off to a fellow in Medicine Hat Alberta. What he sent me back was stunning. The photo doesn't do it justice. For the Comet, I'll buy a Smiths digital tach to match the speedo.

 

[TouringGodet]

RE: 45, versus 47, versus 50 degree V Twins, I thought I heard that the ignition used by many of the Vancouver boys was programmable independently for each cylinder, so that the 45 degree trigger could be retained, and the timing for just one cylinder could be retarded x number of degrees more than the other?

 

[Michael Vane-Hunt]

On my twin that has the Smith- McDougal Harley ignition the little cup that rotates about the sensor is modified. John welded up one side or the slot and opened up the other side to accommdate the Vincent 50 degrees. I do not have a programable ignition on the twin. Every thing can be fitted under the mag cowl but with little room to spare.

 

[Oldhaven]

I believe a way to use the Harley ignition if you have a housing to mount it in is to modify a Buell Blast rotor cup by milling a slot for the second cylinder at the correct angle. I am not sure if the beginning or the end of the slot is the trigger event.

 

[bmetcalf]

Here is the Blast rotor: http://buellsterparts.com/product.sc?productId=2568
The Buell XB rotor has more than two notches, so it must work on a different principle than the big twins , see https://st-paul-harley-davidson-bue...e-buell-trigger-rotor-2003-2007-xb-models-u9a
This is from my 2007 Buell XB manual

The cup only goes on the end of the camshaft one way, so the manual doesn't say if the leading or trailing edge triggers the spark. Someone from the Vancouver lot surely knows. The HD big twins seem to have two notches, so the modified Blast cup should work. https://www.denniskirk.com/daytona-twin-tec/timing-rotor-rotor-32402.p209451.prd/209451.sku

 

[eglijim]

RE: 45, versus 47, versus 50 degree V Twins, I thought I heard that the ignition used by many of the Vancouver boys was programmable independently for each cylinder, so that the 45 degree trigger could be retained, and the timing for just one cylinder could be retarded x number of degrees more than the other?

This was my understanding of some of the available systems so I could not see any point in re-inventing this particular wheel. If what the specs say is correct, the user can select the advance at the low end of the range to accommodate kickstarting or electric starters as well as rev limits and more for a very attractive cost in addition to making a custom curve if wished. The original question was do we know the power consumptions of the various systems as i can not seem to find this info online ?.

 

[eglijim]

Here is the Blast rotor: http://buellsterparts.com/product.sc?productId=2568
The Buell XB rotor has more than two notches, so it must work on a different principle than the big twins , see https://st-paul-harley-davidson-bue...e-buell-trigger-rotor-2003-2007-xb-models-u9a
This is from my 2007 Buell XB manualView attachment 19975

The cup only goes on the end of the camshaft one way, so the manual doesn't say if the leading or trailing edge triggers the spark. Someone from the Vancouver lot surely knows. The HD big twins seem to have two notches, so the modified Blast cup should work. https://www.denniskirk.com/daytona-twin-tec/timing-rotor-rotor-32402.p209451.prd/209451.sku

Thanks for the update, up to now the only system i have seen which does not use the Harley cup type rotor is the Dynatek 4000 race system which has the electronics mounted remotely and uses a more familiar backplate and pick ups with a central rotating magnet.

 

[Michael Vane-Hunt]

This is John's Harley electronic ignition housing.

 

[eglijim]

Dear Jim,
Would you care to share the source/manufacturer of your speedo of choice with data logger.

We normally used Elliot tachometers as they were available with an appropriate analogue scale ,0-8000, and optionally black or white faced. The speedo i have is by SPA and bought from Demon Tweeks ( £140 )ages ago ( 20+ years) when there was nothing else similar i could source, not pretty but pragmatic so may not suit some owners. As I said , it has been an invaluable tool when setting up different carbs in the past. The SPA proved very easy to install and trim accurately, you do have to scroll through most of the memory and functions at a standstill to make notes safely.