Just wanted to update this thread a bit.

The TC88 has been running like a swiss watch. The only knock against the Thunder Heart is there's only one curve per switch selection. What I mean by that is there's no "VOES" like action. Deep vacuum cruise doesn't have a more advanced curve so the pull at light throttle is a little more muted than if the curve was hotter. Other than that it's an outstanding plug-n-play device. Once I go Hi-Comp pistons and cams I'm sure that weak light pull will be a thing of the past and I'll appreciate a less advanced curve at those ranges.

Also, exhaust temps have been basically the same as they were with the Evo. Highway cruise is around 1500F, with AFR's in the 13's.

 

Have you considered a front and rear final drive swap?

 

What do you mean? Are you talking about the drive ratios in the primary and secondary drive systems?

 

Final drive system.
i switched my front to a 30 tooth and rear to a 70 tooth
This not applicable for your need or requirement?

 

Oh, yea I've monkeyed with changing pulleys and what not. Right now I've got a 65/31 with a 133T belt that gave me 75 mph at 3000 rpm with the Evo, but now with this swap I learned the MM EFI touring bikes came with a taller ratio in the primary so now my 75 mph cruise went up to 3250. The 25T compensator sprocket from my Evo will fit, and I'm gonna try squeezing a 32T pulley onto the trans with the 133T belt. That'll get me around 3050 rpm at 75.

 

I'll be damned if that Evo clutch basket didn't bolt right up in that Twin Cam primary. I'm still gonna buy the 36T TC clutch basket, just to have the correct parts, but I put on 50 miles today and it worked flawlessly.

I also put a 32T front pulley on. Now I'm at 3000 rpm at 75, right where I like it.

I also did a custom curve in the Thunderheart. The preset maps are VERY mild, look at the online manual to see. They basically ramp from 10 degrees to 26 degrees with max advance at 4000 rpm. That's like worse than grounded VOES. So, I made a map that replicates curve 3 on the Ultima ignition with max advance at 30 degrees at 3000 rpm. Now it pulls a LOT better at low and mid revs. I'm sure if there were a VOES option it would have a bit more snort, but I'm going 95" with EZ-Start S&S 551's and milled heads to 10:1 CR so I'd probably disconnect it anyway.

 

What bore size is your goal

 

95" is enough, or to answer your question 3.875"

 

I know that with the right tweaks, a 95” can produce some serious rear wheel hp
Hope you’re havin a great summer!
Ride safe!!

 

I'm going for good midrange pull, not outright horsepower. The way I've got this bike geared now she needs torque in the midrange. It'll hold 80, but not light any fires accelerating from it. Back a few years ago I built a 95" TC for my dad's 04 Ultra with Andrews 21 cams and very mild headwork I did myself (cleaned up the valve seat transition and resurfaced the seats, that's it). She pulled nice, but I still felt things could be better.

FFWD a few years and now my bro in law owns that bike and built it up to a 103" with the SE stock conversion stroker crank and some Wiseco 9:1 pistons with S&S 551 EZ cams. I absolutely love that combo in his bike, but I don't want to buy a stroker crank. I'm going a similar route but raising CR up to the S&S recommended max with the 95" cast pistons he took out of that TC. I'll probably also clean up the valve seats and get some high lift springs, but that's it.