Tag: Motorcycle

The amount of knowledge on the IPCRC is truly amazing.  A half dozen people know their stuff about fuel injection and are supplying a lot of great suggestions and pointers.  The thread is a wealth of knowledge for me.  If only I had more time to devote to this project at the moment.  In the next month I have a bunch of travel and work obligations that will take me away from converting my bike.  I’ll still get some things done but not as much as I want.  Maybe in the next month I can get some preliminary designs completed and make a parts list.

Looking at the NT-700 microfiche, the throttle body assembly (16400-MEW-L01) looks very promising.  It includes the throttle bodies and injectors in one unit.   There wouldn’t be any room to tune the volume between the throttle bodies and the valves though.  Someone on the IPCRC suggested I try to match the volume of the cylinder to the volume between the valves and the throttle bodies to help compress the air as it enters the engine.  I could also do that with a turbo or super charger, too.  However, it would be very difficult to tap the exhaust and there aren’t any belts to draw power from.    An air ram would almost be better although it would be a wee bit ridiculous to put an air ram on a PC.  Never say never though…

Anyway, if the angle of the cylinders is different between the NT-700 and the PC-800 (I suspect it is based upon other engine drawings), it won’t fit quite right. Also I suspect the throttle bodies are smaller diameter on the NT-700 as it is a smaller engine.  If anyone reading this happens to have an NT-700 kicking around and wouldn’t mind measuring the throttle body internal diameter and also checking distance between centers on the throttle body and angle of the throttle bodies, that would be a HUGE help.  To buy that assembly would set me back $5-600.  Not exactly something to buy lightly!

I’ve been thinking more about using the MegaSquirt kit to do the fuel injection timing.  It seems very flexible and has a large community of active developers and tinkerers.  The unit I was thinking about using though seems like it might not be released (MS-II Sequencer).  However, it seems like the MSI, MSII, or MSIII should work.  Especially with the “Extra” firmware.  Then I get a bunch of other fun management potentials (nitric oxide injection, spark management, etc).  This page seems to have a descent rundown of what’s what in Squirt-land.  It also seems that Wikipedia is useful to better understand all of the available squirts.  One of my buddies has experience using MSII.  He bought it from DIY Autotune who he says is a good company.  There are mods and kits to make the MSII do nitric oxide injection.  Also can do methanol injection with the NOx to give extra oomph.  That would be a future project…  And hella fun.  Although I probably would need a new engine after that 🙂

Looking at the schematic for the spark system for the PC800, it appears we already have the necessary sensors to feed information to a MegaSquirt for cam sensing.  That is VERY good news as there isn’t anywhere to attach an external sprocket and sensor on the PC’s engine.  Hopefully I can adapt the MS to take the ignition pulse information.

All the extra room under the gas tank that I’ll be left with is opening up some interesting possibilities…  I’m thinking about installing a comm unit, some radios (CB, FRS, a few amateur bands, etc).  It would also be great to have that extra space for auxiliary switches and dodads.  I’ve been wanting to install auxiliary gas tanks in the trunk.  A few switches on the faux gas tank would allow me to have transfer pumps and whatnot to trim out weight distribution in those rear tanks and also feed that gas into the primary tank or from the primary tank into the rear tanks.  Who needs an aircraft when you can cross-feed your fuel tanks on a PC800?

A post from Jerry on the IPCRC brought up the point that the throttle bodies that the VT750S uses have a 90 degree bend in them to allow for a side air cleaner box.  That won’t work very well with the PC800 setup.

Looking at the PC800 microfiche, I wonder if I could use the PC800 throttle body and carbs with some heavy modification.  I could drill out the jet ports to install the fuel injectors.  All of the random diaphragms and other parts could then be removed and the various leftover holes could be sealed with JB Weld or Hondabond High Temp Engine Sealant or screws or metal plates, etc.  It wouldn’t be as good as a purpose-made throttle body but it might work.  And it wouldn’t require any modification to the stock air box.

Now if only I had a spare set of PC800 carbs laying around to experiment with…  I fear I will be removing the carbs on my bike several times to take measurements and figure things out in the coming months.  I’d rather have everything ready to drop into place once.  It wouldn’t be so bad taking apart the bike all the time except for the small problem of me not having a garage.  I do all of my work in a parking lot outside the fraternity where I work (I’m the house dad).  I have to button up the bike every time I’m not outside working on it.  That becomes tedious very quickly.

I wonder if there are any automotive throttle bodies with fuel injection that would be the right diameter.  Or maybe motorcycle throttle bodies.  Surely there must be some vehicle with the same diameter intakes.

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.