PC800 Fuel Injection – Page 3 – Not Your Average Engineer

April 19, 2015

Getting Closer with the Honda Pacific Coast PC800 Fuel Injection Tuning

I spent some time today on my Honda PC800 fuel injection conversion project. I am getting the tune file together so that I am ready to take the bike to a dyno for final tuning. The biggest things that I still need to address are 1) tidy up the wires, 2) adjust the TPS sensor so that it can sense low throttle positions, 3) finish up the primary tune, 3) figure out the enrichment settings for startup/warmup and acceleration.

I’m going to try setting up a very old NetBook running Ubuntu with TunerStudio so that I can have the ability to modify my tune while I’m out and riding. Also that will allow me to more easily log data. At some point I’ll probably get the BlueTooth wireless adapter to be able to log data with my phone while I ride.

Slowly but surely my bike is coming along! By summer, I think I’ll be out and riding again.

December 9, 2014February 24, 2015

Building a Vacuum Reservoir for a Honda Pacific Coast Fuel Injection Conversion Project

This humble pipe will be the vacuum reservoir on my Honda Pacific Coast PC800 fuel injection conversion project. I have been working for some time on converting this carburetted bike to fuel injection. One issue has been a fluttering manifold air pressure reading from the Manifold Air Pressure (MAP) sensor when it is hooked directly to the intake runners. The solution is to have a vacuum chamber to smooth out the pulses from the opening and closing of the engine valves. The pressure readings will still be correct but without the huge flutter problems.

I JB Welded in brass fittings to the two screw ends of the PCV pipes. Once everything is dry, I will bolt it all onto the bike under the plastic.

December 7, 2014February 24, 2015

Adding Vacuum Taps to a PC800 Throttle Body

I did some work today to add a second set of vacuum taps to the Honda Pacific Coast PC800 carburetor that I have modified into fuel injection throttle bodies as part of my long-running fuel injection conversion project. In this photo you can see two metal pipes penetrating the lower portions of the throttle bodies. These pipe taps will act as vacuum taps. I am going to hook either the Manifold Air Pressure (MAP) sensor or an Idle Air Control (IAC) valve to these taps. The other existing factory-installed taps will be used for the MAP or IAC that isn’t plugged into the new set of taps.

Here’s the finished view with vacuum hose hooked to the new taps and the new tapx shaved flush in the throttle bodies.

My finger is pointing to the new tap.

All in all, it was a pretty clean installation. I used JB Weld to hold everything together. Hopefully the 10% ethanol gas that we get everywhere in the USA won’t someday degrade all of the JB Weld that holds together the throttle bodies.

The throttle bodies installed on the bike. Lots of hoses and wires running everywhere to make this bike come alive! Up next is figuring out how to make the MAP sensor not flutter all over the place (vacuum reservoir) and finally figuring out how to do proper idle air control using an IAC that works with my existing MicroSquirt setup. The engine really needs IAC so that it will properly start when the engine is cold.