Been a long summer, didnt have much extra time to dedicate to this project for a while but I have the last couple days.
Heres what I have found out:
The problem I had with my setup is what I always thought based on the way my engine acted, erratic/jumping spark. No matter where I would index or set the flywheel/ignition in relation to crank position when I was able to get it to fire up and run the actual timing wouldnt change much on the light and my timing marks.
This led me to try and figure out the "why" not so much the "just get it running" approach.
I had tried what Scott and his dad did when building another engine that involved using a polaris flywheel (older XLT) with a riveted hub setup from an older 900 tcat. After some machining I had a perfectly setup modified new flywheel setup which they got to work properly. I had the same result as before it didnt want to run.
I finally tried my tcat ignition but finally with a tcat ignition sensor (so now for the first time 100% tcat ignition) which is what everyone in the past had run with great success . The appeal of running a newer twin reprogrammed ignition was for many reasons, availability, custom programming, and potentially engine reverse! Once I went 100% tcat my engine came to life, and ran better than it ever had! Granted it was over 50 degrees off on the timing but now I could start to make forward progress!!!
Ignition parts incompatibility is what had me pulling my hair out trying to get this thing going correctly. With Scott and his dads older engine setup with the twin ignition this is what they ran and it worked, they later built another one after the problems I had in which they then had the same issues as I did (two twin ignition triple engines not working and only one that was) IMO the one that worked is the oddball, for why it works is honestly still a mystery! The theory is that the twin CDI has smaller discharge capacitors internally that in twin configuration has more time between sparks to recharge, with a triple cylinder setup, you have more draw with a second external ignition coil and less time (120 degrees of crank rotation vs 180, along with three sparks per 360 degrees of crank rotation). We're assuming that the one running twin CDI just had stronger capacitors although they changed this engine to the polaris xlt flywheel and they got it to run whereas I mirrored their new setup with the same results I had previously. This is only theory maybe right maybe wrong. I just know originally 2 out of 3 didnt work.
The key for my engine was the trigger sensor itself. I had to build a custom bracket for inside the mag housing for the tcat sensor to bolt in the twin case end. It is thinner than id like but it still keeps me from cutting the big hole on top of the mag housing and mounting the sensor which was a goal for me.
All that along with yet another keyway cut in my flywheel (four now) and were in business other than just waiting for some decent snow!
Ive built a variety of different engines, most were always straight forward, ive probably learned more on this venture than any other engine build but I still feel this engine has its place on the snow for the HP junkies! In the future the Cutler one piece cast case is the way to go IMO, along with a complete 100% tcat ignition with a retapered flywheel hub to prevent the keyway from sheering due to incorrect taper angles, preferably newer tcat cdi with a TPS sensor and rackslide carbs, m1000 pistons, jaws pipes and a good chassis. Triple hood and belly pans are a plus but with a taller twin hood or trimming the stock twin hood it will all fit under there!