I started by going up 3 teeth from 27/70 which is my Killshot gearing. But after some more testing I went back to the same gearing of 27/70 but am running the timing so it pulls 12 amps. Now it has great bottom and screams on the top end. Comes off in the high 150's after 5 minutes. Loving this motor more every time out with it.

So is there a benefit to running the 13mm over the 12.5mm rotor for club racing with the D4? I am running the D3.5 Maxzilla but am considering going with the D4 17.5 (buggy) and 13.5 (stadium truck) with either the 12.5 or 13mm rotor. Just not sure on which route to go or if it would even be worth the switch

It's not legal so don't even run it at a club race.
It's like running the 3.5 motor it's not legal and just being a cheater.

Not necessarily. The D3.5 is only illegal for ROAR events. Most club races will allow them. This is why they are not being discontinued. Same goes for a 13mm rotor. It's illegal for ROAR events but most club races dont follow ROAR rules that closely.

I bought the D3.5 from my club a month ago... 2 races on it. He still orders them in. In fact he sold me two so I'm not going to just toss them out. I didn't know that the D4 was being released becuz I'm just getting back into the hobby or I would have gone with it. I'll switch over once I get a little more time on the track

corrected for accuracy.

i get not following ROAR rules in mod classes (like allowing use of 4 pole, 550 motors in 4x4 SC for example), but in stock classes, a track is doing it's racers a disservice if ROAR rules aren't enforced. otherwise you'll have guys with cheater rotors, ramped timing, etc. stock is expensive enough, but when you have to keep up with the latest cheater gear, i can see it getting way out of hand.

If you can still run the D3.5 then go with that. The D4 might be the newest motor out of Trinity's shop. But its still not as good as the D3.5

So what does the timing in degrees come out for you to 12 amps? I'm just curious as your setup seems different than others. Most seem to be in the 32-35/70 range. You are much lower. I would think that you would have great acceleration but not much top end. But then again, I'm assuming buggy, you might be running sct or truck.

Curious as I'm always looking for other things to try out.

Now why would that be

Right about 61 and I am running 2wd buggy on a medium size track for 10th scale. We are finding in testing the D4 can run at a higher amp draw then the Killshot did. With the Killshot we would run 10 amp max but with this motor guys are going all the way up to 15 amps. When you add this much timing to a motor you gain incredible top end but loose on the bottom. So to compensate you gear lower to get back some torque. I usually go between 27-29/70. I tried 32/70 with 50 degrees timing like most run and I felt the motor was flat. I think what I have now is much better.

61* timing hummm

Yes but it wont be the same on every motor due to tolerances varying in the build from motor to motor. This is why I prefer using a inline meter instead of the hash marks on the endbell. Once you get close to 11 amps the RPMs really jump up with just the sligtest adjustment.

Do you have pics/details of your inline meter setup?

This is the unit I use. It gets the job done.
http://hobbyking.com/hobbyking/store...h=watt%20meter

Thank you