new cafe racer project CB750 1979

[The13mack]

Here is a pic of the start of my new project.
so far i have got it started briefly but the carbs leaked and i didnt want to run the bike anyway with old fuel etc. the plan is to make it run great (keeping the airbox on for now) then strip and make a cafe racer. is not the worst thing ive started with so we will see. im not in a rush with this one but am eager to start.

couple of things i wanted to ask peoples opinions on was the following.

1. I inted to use the M-unit blue, what is the smallest battery in size i can use that will give enough power?
1.a when using an Munit how do i know which pieces i can keep and which i can get rid of? i mean in terms of electrics/relays/rectifiers/etc.

2. I want to have a 4 into 2 as i just love the look of them, any one have some examples of the pipes headers and cans that are about? not decided on the cans as yet or angle i will have them at but would be great to have some ideas

3. i want to put a seat hoop on the back, how can i be sure of the best fit? does anyone have a link for one they have bought and used? there are the ones with the light integrated on ebay that arent to expensive but i want to ensure i get the right size.

4. Is there a wider tyre i can have for the back wheel without having to change any thing?

Thankyou for all your help so far. seems alot of helpful people on here.

 

[Nylundarn]

To answer your electrical questions :

1. When building my bike, I read around and many sources stated that you need 200cca minimum for a 750 DOHC, I went with a Ultrabatt 300cca and it cranks the engine like theres no tomorrow. Highly recommend.

1a.

For my M-unit conversion I cut out all the grouped components from the original harness, and then spliced them into a new harness with the M-unit as the "core"

These components are:
- ignition coil assembly
- spark units
- stator
- iginition pickup coils
- Regulator/Rectifier
- oil pressure sensor
- neutral sensor
- starter solenoid
- brake switches
- clutch switch (if you have one)

Some things to remember
- The M-unit works as your fuses and indicator relay so you don't need them.
- You need to decide if you are going to use the original controls or momentary switches, you also need do decide what gauges you will be using.
- IF you go for a Lithium battery, you HAVE to replace the Regulator/Rectifier with a Lithium compatible one.

Give me a moment, I will find a wiring diagram and circle the component groups for you.

 

[brettp]

Nylundarn,
Did you have a clutch switch to keep?

 

[Nylundarn]

Nylundarn,
Did you have a clutch switch to keep?

Nope, mine didn't have one. But good point, he should have one.

 

[Nylundarn]

In PDF I have circled the parts you would normally keep in a conversion.

 

[The13mack]

Nylundarn i have to say you are a mountain of knowledge especially for idiots like me, dumb question time, why in your diagram are the circled bits in different colours.....

 

[Nylundarn]

Nylundarn i have to say you are a mountain of knowledge especially for idiots like me, dumb question time, why in your diagram are the circled bits in different colours.....

No problem, the colors have no real meaning. I just like to paint!

One more thing I would recommend : If you cut into your original harness, be sure to cut "after" the plugs. That way if any of your original components die, you can always just plug in a new one.

Just hit me up if you need any help.

 

[The13mack]

No problem, the colors have no real meaning. I just like to paint!

One more thing I would recommend : If you cut into your original harness, be sure to cut "after" the plugs. That way if any of your original components die, you can always just plug in a new one.

Just hit me up if you need any help.

seems to be a world shortage on the battery you suggested. any other makes of the same type you know of?

 

[Nylundarn]

seems to be a world shortage on the battery you suggested. any other makes of the same type you know of?

Cant really speak on any other batteries, just stick to some reputable brand with good reviews. The form factor is important, depending on if you are going to empty out the under seat "triangle" or not.

 

[Ohio]

In PDF I have circled the parts you would normally keep in a conversion.

Thanks for this. Starting down this road myself and it’s really appreciated.