Dear Diary: Fabrizi 50mm bore portmap/Port timings

[DirtyE]

Theres more than one way to skin a cat.

[DirtyE]

With the new timings, the powerband is much more evident. My clutch grabs a little after 7k and i can ride at 35ish all day. Approaching 9.2k the powerband KICKS in and packs a punch. I'm really digging the current setup. A lot of the roads around here are just 25mph so i can just putt along if i like quietly, and if i want a loud screaming 11k scoot i've got that in the pocket. Temps are still good maxing around 370. My blowdown is creeping up closer to 35 and im not a fan of that, but i think i may go a little higher to see if i can raise the beginning of the powerband up past 10k. I'd assume raising the exhaust would raise the peak RPM of the powerband at the bottom and the top of it.

[Downsouthdio]

Its awesome aint it !!

[DirtyE]

Sort of. Im getting to the crunch zone. A half millimeter could screw me now. I think im going to remeasure everything before i bring the exhaust up anymore. It feels great, but can i squeeze more? Risk vs reward.... To be a truly skilled tuner here isn't just to cut blindly. I'm going to have to remeasure everything. I brought my squish down to .65mm which is near that of what the fabrizi manual says it should be, but im not certain this kit isn't made for another bike. Things seem a little fishy. The stock port timings were very tame, and the the stock squish was at .9.

I've got 2 pieces of solid motivation. a 26mm carb, and a yasuni c16. With those two things on the front and back of an 81cc Fabrizi kit, i feel like i should be getting more.

[DirtyE]

Now with the lower squish, you can see if i bring my exhaust port up .5mm it will result in an aggresive exhaust timing, but critical blowdown. I could raise the transfers a pinch, but im concerned with the accuracy on my hand piece. I suppose i could raise it a half mm and run it. Whats the worse thing that could happen?... dont answer that.

[DirtyE]

Brought it up again today. Added a generous chamfer to my transfers and boost as well. Powerband is kicking in closer to 10k and good power is being made til the max RPM of 11.9k. I inserted the ring and pushed it up us I g the piston to make sure both sides of the exhaust were opening at the same time... same for transfers and boost.
I also brought the cylinder skirt under the transfers and boost port up closer to the bottom of the cylinder.
I am still unable to touch 12k, but im getting closer.