Topic: '78 CB750K Project #2 - Digital Dash Panel w/RFID

[Stoli]

Time to start working on the second bike. Another '78 CB750K. I was really torn between restoring this one to stock or modding it into something else but in the end I decided to go the cafe route.  I have finished pounding on the tank, trimming the side covers and fabricating the seat. Just put a coat of epoxy primer on the tank and seat while the temps outside are still warm enough to paint. This bike will be more of a traditional cafe style than my first project.











But here's the twist .... I am going to outfit this with a digital dashboard on a 7" Android tablet. I don't know if it will look stupid or not, but at this point I don't really care. One thing is for sure ... it will be different, and that is my goal. That's why I like these old Hondas. You don't see a whole lot of them around here. Every swingin' dick in this state has a Harley. I don't have anything against Harleys but I just don't want my bike to look the same as everyone else's.

Here is a screen capture of the android app I am working on. Just running a test pattern at this point while I work on the sensor circuits. It will receive the data over a bluetooth connection so no wires required to the tablet unless I need to charge it. Will outfit the bike with an RFID ignition switch as well.



(just a test pattern - I doubt my old CB750 can do the ton in 3rd gear).

[SOHC4 Cafe Racer Fan]

Nice job on the knee dents.  What's the story on the seat?

[Stoli]

Made it out of fiberglass. PITA but the benefit is that you can really get a nice fit with the tank.

[SOHC4 Cafe Racer Fan]

Made it out of fiberglass. PITA but the benefit is that you can really get a nice fit with the tank.

No kidding!  That's form fitting.  Nice.  You should make a mold and sell those!

[Stoli]

Actually I still have the mold. The problem is that I'd have to charge $750 per seat to make it worth my while. Painting and fiberglass are tied at the top of my "things I'd rather not do" list.

[lwahples]

Nice start on the winter project.Seat came out Sweet!

[70CB750]

The black is sexy but I dig the application. 

Maybe in 4th gear? 

[flybox1]

The black is sexy..... 

+1
lookin' good  
well done on the tank dents and seat!  Its a great fit with the lines of the tank.

[Stoli]

Thanks guys.

Check this out. A true classic. The PO must have had some problems with the headlight positioning so he put a sheetrock screw through the head light ear and into the bucket to fix it. Move over Red Green, you have some competition.




Although, Red would have used duct tape...

[toytuff]

Subscribed!

tt

[iron_worker]

lol I love PO hack fixes. For some reason the PO of my bike converted to 77-78 style controls but decided he should just cut the old control wires off and leave the chunk in the handlebars? Somehow managed to get the new control wires through there as well? ?

I really like where this build is heading btw.

IW

[Bankerdanny]

If women can't find you handsome, they should at least find you handy.

[Stoli]

Just a little shoutout for Goodhues Powder Coating in Derry, NH. Very thorough, reasonable prices and real nice folks.

[snowman]

Truly an inspiration for my K7 build, can't wait to see the finished product....subscribed.

[brandEn]

Nice start!

[Stoli]

Making a little progress. Got a new headlight bucket and some brackets. Progressive fork springs installed and mounted some Avon tires.

[Stoli]

Engine cases prepped for painting.

[Stoli]

I placed the Nexus tablet at various positions and angles where the gauges were but it just looks weird. So, I think I will mount it on top of the fuel door. Still looks a little odd but not so overt. Needed to change the gauge display to a vertical orientation.

Throttle position and lambda scale in the upper right. Combined the speedo and tach into a single gauge with tach value displayed as orange arc and speed displayed as digital value.

[blue collar]

Looks great. K7/k8s can really looks nice when done right! 

Love how blacked-out everything is 

[Stoli]

Time to start figuring out the electronics on this project. As I mentioned, the gauges will be replaced with a Google Nexus 7" tablet mounted on the top of the fuel door. A CPU mounted under the seat will receive information from sending units mounted on the engine. Here is a list of the sensors:

- RPM
- Oil temp
- Oil pressure
- Fuel level
- Throttle position
- Battery voltage
- Lambda (air fuel mixture)

It will also receive state information from the neutral and directional switches. All of this info will be processed by the CPU then transmitted via bluetooth to the tablet, which will display the dashboard. The tablet will also have a logging feature that can be used to review lambda vs. throttle position and RPM which can be used to fine tune the carbs and determine proper jet sizes. Speedometer and Odometer will get data from the tablet's GPS, so I can get rid of the speedo cable.

------------------------

First up - RFID Ignition. The keyed ignition switch will be replaced with the following:



The RFID is a cheap $15 module from ebay and the catch is that the key fob must be within 3" of the receiver for the unit to be active. So the relays RY2 and RY3 are wired to latch closed when the RFID relay activates and they will stay latched even when the fob is no longer within 3" (so after the ignition is engaged, I can put it in my pocket). When RY2 latches it will provide power for ignition as well as power the LED halo lights on two switches (S1 and S2) mounted on each headlight ear:



The ignition is killed when both switches are depressed simultaneously. So the key fob turns the ignition on and pushing switches S1 and S2 turn it off. I'll need either S3 or J1 to provide an emergency backup in case the RFID or RY2 fails. The stock keyed ignition has a second switch on it that provides power for the tail light circuit. Relay RY3 is used to replace that switch.

[Stoli]

CPU & Power Supply

The brains of the system is pretty straight forward. An Arduino Nano chip will be used as the CPU with a HC-06 Bluetooth module to send data to the Google Nexus tablet.



Will need a robust power supply to provide a stable 5v for the CPU and some of the sensors:

[Stoli]

Tach

** Edit: I replaced this circuit with a different design. Scroll down to see Tachometer v2. **

This will be the trickiest circuit to get to work. I will replace the tach cable with a wire coming off of one of the coils.

[Stoli]

Oil and Fuel

Oil and Fuel sensors are pretty straight forward. The sending units are just variable resistance, so a simple voltage divider circuit on each sender can be used to convert the resistance value into a voltage between 0 and 5 (the voltage range that the analog input pins on the Arduino requires).

[Stoli]

Neutral, Voltage, and Turn Signals

Hopefully this will work. Assuming I interpreted the Honda wiring diagram correctly:

[cheftuskey121]

so not trying to come off as an @$$, but what's the point? is there some added benefit, or is this purely "because I can"/"why not"? I am all for seeing boundaries get pushed, it's definitely unique. obviously its not meant to be stock, I get that, I'm just trying to get an idea what you're doing here. I might add I am loving every minute of it!