Using Ignition Modules Tach Output as RPM Signal to MS3 3.0

[alan1570]

I have a question about sending a crank tach input signal to my MS3.0. My Dad, Brother and I make up the Tri-Mac Speedsters land speed racing team. We currently have a 100cc bike project where we are using an MS for fuel only. We are using a special constructed Ignitech ignition module which has a tach output from the CDI box. I have read success stories of people that have used the tach output of a ignition module to signal an MS crank input. I am having a hard time finding the details on any modifications to the board required. My question;

What modifications are needed to the MS board so that I can use my ignition module tach output to provide RPM signal to my MS? Example modifications would be Coil Negative, VR, Hall that require some jumpers and/or electrical component arrangements.

I have attached one document I have found for Fuel Only Implementations found on DIY Autotune site. This document mentions the use of tach output from CD control box.

Will the MegaSquirt work with my stock ignition system_ - DIYAutoTune.com.pdf

(228.98 KiB) Downloaded 8 times

We have thick skin so we can take some abuse if anyone needs to point out something I over looked, please let me know.

Thank you,
Tri-Mac Speedsters

[alan1570]

Update: I could not obtain a RPM input to MS through ignition tach output. I am sure this could be done if we had a sparky on the team. We needed to get to the tuning stage ASAP as Speed Week is right around the corner so I swapped the MS tach circuit over to VR. I now have RPM being registered in tunerstudio using stock flywheel puslar that came on the engine. We are back on track and should be tuning the engine next month on the home chassis dyno.

Tri-Mac Speedsters

[jsmcortina]

Hmm, not sure why it didn't work out. I thought I'd answered this post to say that it ought to work, but clearly I didn't.

Anyway, good to hear that you are seeing RPM now.

James