NOTE: I have created a new category where I will be posting research, information, and eventually a how-to for installing fuel injection on a carbed PC800. I’ve given quite a bit of thought over the last year of PC800 ownership about adding fuel injection. I finally decided the time is now to start figuring things out and moving forward on this project. Is it crazy? Yes. Is it possible? Yes. But it will take lots of determination, some money, and me being crazy enough to subject my poor PC to modification and tuning. Let the fun begin!
My First Brilliant Idea
As the new Honda Shadow VT750S has fuel injection on-board, swapping that system onto a PC seems promising. The VT750 shares heritage with the PC800 engines. I
was looking at the parts microfiche for the PC800s and VT750S. Everything on the engine up to where the carbs would bolt on looks the same (ignoring the PC800 being tuned more “sportily”).
I need to find someone with a new VT750S who would be willing to look at the bike and take some measurements for me. Specifically, the carb insulator boots (or I guess
these would be fuel injector insulator boots?) interest me. They have different part numbers (PC800: 16211-MR5-670 vs VT750S: 16211-MFE-640). However, looking
at the microfiche they sure do look similar. The big question is if the tubes that lead into the cylinders are the same size between the bikes. (Basically where #7 is pointing on Page 5-4 of the Service Manual)
If they were the same, then it becomes much more reasonable to pursue using the VT750S fuel injection system. PowerCommander already makes a unit that will interface with the VT750S Honda ECU which will allow tuning for the higher RPMs that the PC800 uses.
Another Good Idea
Otherwise, there are several companies that make custom fuel injection systems or I could do it myself and learn the black arts of fuel management. Obviously, I’d prefer sticking with Mother Honda, even if the parts weren’t exactly made for the PC800.
The best system that I’ve seen so far is the MegaSquirt. It is a do-it-yourself hobbyist controller for fuel injection. Just buy your injectors and a few other parts, throw it all together, and start tuning. Or something like that anyway. One of my friends, Michael Q, happens to be a member of the hobbyist community built around the MegaSquirt. He has already offered his help.
If I went with the MegaSquirt, I could also eventually add ignition timing control and possibly expand to have cruise control and someday nitric oxide injection. This is a list of things that I will absolutely need to make it work.
Douglas,
I will be following your project with interest.
I think the system you will come up with for the PC800 will be capabile of being used on a larger displacement engine like the vt1100. I will work this mod while you solve the fuel/ignition management system.
A few thoughts on the injectors. There are several FI thottle bodies out there. Clearly using the one for the FI Shadow makes it easier, but I wonder if you can adapt ones from another application and use the PC linkages?
I’ll let you know how the addition of the oxygen sensors go with the dual exhaust project. The sensors are being set up so I can tap into them later – like for a FI set up.
Jerry
Jerry,
I’ll be interested to see what you come up with for the VT1100 engine. The engines and bikes are similar enough that we should be able to share ideas and designs back and forth pretty easily.
I think the hardest part for using FI throttle bodies from non-VTxxxx engines is adapting it to fit the engine. Also I could see the throttle body internal diameter being iffy. I think it would be okay to have larger than stock openings but smaller than stock and we’d have issues with not enough air getting into the cylinders. Also we’d have to make sure that the throttle linkage was roughly the same so we wouldn’t have to change out the throttle control on the handlebars.
If only I had access to a CNC, I’d design my own FI throttle bodies and machine them myself so I can do proper port injection. Certainly it isn’t hard, just expensive for machine time. Then I could add the nitric oxide ports easily. Otherwise, I think I am going to have to find some dual FI throttle bodies and up-size the injectors so one injector in each throttle body can be for fuel and the other for the NO. Or instead of going the multi-port route, I might end up doing the throttle body route and have the injectors feed both cylinders above the throttle bodies.
From what I can tell from the parts microfiche for the VT750S, there is no O2 sensor in the exhaust. I’ve been told by a friend that it isn’t strictly necessary to have the sensor. Does the VT1100 exhaust link up under the bike somewhere? On my old VT700 with dual exhausts, it had an exhaust pass-through above or around the shaft drive. It wasn’t obvious unless you jacked the bike up and looked underneath. Not sure if that’d provide you with the sensing abilities you need but it could be an interesting place to investigate. On the PC800, I’m sure there is somewhere convenient that isn’t chromed that can be drilled and have the appropriate sensor installed. Now if there is clearance with everything else around it… that’s a different question.
Cheers!
Douglas