Popped the lid of of the carbs and started the mod. The thread size on the B42/55 is a 6mm x 1mm standard thread. The tap drill for that thread is a #9 which is .194" I measured the bore of the air jet in the body of the carb at .191" so there was no reason to have to run the #9 bit in the hole, just tap it out to 6mm X 1mm. Tapped it in 5 threads, cleaned the hole with a vacuum and pulled the choke plunger out to ensure no aluminum thread filings. Inserted the jet and Bob's your Uncle. So I've choked down the air to the choke circuit from .191" to .110" using the B42/55 X #280 jet.
I also like the nice clean look. If I decide down the road to change the orifice size, the B42/55's are available in #70 (which is .7 mm) to #290 (which is 2.9 mm)
The following user(s) said Thank You: scotch, zed_thirteen, StanG
It's been so long since I posted to this topic, I wasn't sure if it was still here.
It's Cyber Monday here in North America and online shopping deals abound. I've gone and done it now. Went to www.diyautotune.com and they're having a cyber Monday sale at 10% off, so I bit the bullet and bought a Microsquirt with a 30" harness for the project.
Microsquirt V3- a stand alone programmable ECU that will run 2 circuits of injectors in batch fire, and up to 4 channels of ignition, so by using 3 channels I can run the KZ in wasted spark. It has the ability to run in either speed density ( throttle position + manifold absolute pressure) or Mass Airflow. It also has provisions for O2 input in either Wideband or narrow band.
What I really wanted was to buy a Megasquit 2 kit and build it but size wise, it would have been a bugger to fit. The microsquirt has all that the Megasquirt 2 has but size is small due to surface mount Technology (SMT) electronics and that keeps the board small. The entire Microsquirt measures 4.71" X 3.13" X 1.67".
Looking forward to fitting this to the bike when the time comes. It's the kind of thing that gets me stoked.
The following user(s) said Thank You: biltonjim, zed_thirteen, mizztheman
Is there any way you could re-purpose the empty carb bodies as throttle bodies? Just thinking aloud.
Won't have to. I picked up a set of ZN throttle bodies for $ 70. I think just for giggles, I'll get it running with the carbs and then switch out the carbs for the throttle bodies.
Options are wide open now, especially with wideband O2. I'll be able to monkey around with the carbs and see what happens and then the same with fuel maps with the throttle bodies.
Another big deal is the ability to set the dwell time for the primary side of the ignition coils and be able to saturate the coils and not overcharge/overheat them. Coil selection is now wide open and no need to restrict voltage to the coils with a resistor in order to not burn out the coils. I.E. maximum output from the coils without consequences.
That's why this kind of stuff gets me excited. It's experimenting with measurable capabilities rather than following blindly down a dark alley. The ability to mix and match anything with the ability to control all aspects. Nice thing with the Microsquirt is that you can alter the parameters and upload rather than burning in a new PROM chip for a stock computer or tricking the stock computer with false inputs to get the desired outputs. The Microsquirt can be used to run a Chevrolet LS engine in batch fired injection and wasted spark. Pretty good for a $500 Stand alone ECU I think. We'll see how it all works out.