Honda CB 750 -79 Cafe Racer -project from cold Finland

[Macce88]

Update - Deadline 1.

End of the last year, I decided that deadline for my bike is 31th of January, so it should be in Finlands biggest motorcycleshow in early february.
As you can see, I didn't make it, BUT I got a call from event organisator. They would still be happy if my bike can make it, even it is not ready...

So 2.-4. of february my bike is in the show.
It is not painted nor 100% finished, but still.

It gave me lots of motivation and there is so much going on right now



Start-button
As I wrote, I got start-button from a friend.

We scan it to 3D-model and after that printed it.
It came pretty good. Few minor grinding to do, but it works!


Original button


First version


Final version


Need to polish it and its good to go


Steeringstem
Way back I ordered steeringstem adapter to fit GSXR front end to CB750 frame from Cognitomoto. Like they said, it is almost bolt-on.


Original GSXR stem in triple tree, next to new stem.

Just press the old one out and new one in


Here you go.



Part, parts and more parts
Almost everything has been ordered and delivered (I have said this thousand times )
Just arrived. New tires, blinkers, bolts and nuts...





Still to come: exhaust tips with removable silencers, front fender brackets, brakehose brackets...



Welding and grinding
Yesterday we welded few last things and just exhaust brackets and supportframe for carbs are still left.


Sidepanels grinded, rings for hoses and wires, swing arm spools/sliders bracket, grinded small piece from swing arm, that hit the engine.


Moved licenceplateholder closer to the wheel, extension to the seatpan, supportpiece to rear shock, brakehose bracket and moved side stand forward, because it was too close to shiftingrod.



Seat and exhaust

I have talked to upholstery who will make my seat complete. It will be done just after the motorcycleshow in february.

Also talked to man, who will make exhaustpipes for this bike in february.
Four invidual pipes from the engine. Two of those will join together on each side under the engine. Two silencers, one in each side will come out just under rear footpegs.
Pipes will be ceramic-coated.


Assembly of the bike is starting next week and then we are going work with rear cowl.

Now it looks like this project will finally finish before this summer

 

[Macce88]

We are now swapping front end with correct parts.

As you saw in my last post, stem is already in its place.
Yesterday we push bearing housing to the frame.







I ordered two silencers and they look like this:


Exhaust tips will come like this, but not that far:




Few questions to you readers

1) Enginepaint. What do you suggest, when bike is aircooled? What paint and how? Color should be semi-gloos black.

2) What options is for carburators if I want to get rid of original ones, as they are pain in my ass to get work right.
I would like to get list of carburators from another bikes and also aftermarket-carbs that would do the thing on my bike.

3) Front sprocket is on my searchlist. Below you can see original splined one. I would like to buy 15- or 16-spikes on 530-chain.
What bikes share the same splines? (VFR?).


4) Is the original front sprocket to chain 530 or to something else?
Has someone welded two sprockets together, to get some off-set?

5) What kind of setup on sprockets you run? I'm thinking 15/40. Is it okay to get some lower torque, but still runnable on highways without hitting revlimiter at 50mph?

6) Where can I order new VIN-plate for my bike?
Picture below.

 

[amc49]

'...still runnable on highways without hitting revlimiter at 50mph?'

You will find any bike geared to approach that will be impossible to use on the street, you're talking 9500 rpm at 50 mph there. You will be seriously overgeared at 100 mph.

Similar with the VIN plate, not supposed to be easy to get those, what every bike stealer in the world asked for at Christmas.

 

[Macce88]

'...still runnable on highways without hitting revlimiter at 50mph?'

You will find any bike geared to approach that will be impossible to use on the street, you're talking 9500 rpm at 50 mph there. You will be seriously overgeared at 100 mph.

Okay.. I don't get it.
Original setup is 15/38, so two spikes bigger rear sprocket affects so much?

I calculated with this http://www.gearingcommander.com/

It says original setup 15/38 -> 5th gear 50mph -> 3688rpm
It also says new setup 15/40 -> 5th gear 50mph -> 4202rpm

I like to have you own experiences, not just calculated theory.

 

[Neilx7]

for vin plate try this web site

http://www.vin-plate.co.uk/motorcycle_plates.html

 

[Neilx7]

http://www.vin-plate.co.uk/number_punch_kit.html

 

[dirtdigger]

As far as carburetors go with Keihin CR carbs or Mikuni RS carbs. http://cyclexchange.net/DOHC PARTS pAGE.htm

 

[amc49]

All I was saying is that you better not be hitting redline (which is usually the same thing as rev limiter) in high gear at 50 mph.........tire size affects the OVERALL ratio as well as tooth size.

 

[Macce88]

for vin plate try this web site
http://www.vin-plate.co.uk/motorcycle_plates.html

Thanks!!

As far as carburetors go with Keihin CR carbs or Mikuni RS carbs. http://cyclexchange.net/DOHC PARTS pAGE.htm

Thanks! I have to do some kind of saving plan for these

All I was saying is that you better not be hitting redline (which is usually the same thing as rev limiter) in high gear at 50 mph.........tire size affects the OVERALL ratio as well as tooth size.

Okay. I did change tire size also.
Just wondering what kind of setups you guys run, so would 15/40 setup be okay?

 

[amc49]

I ran 17/42 on mine, or close to 1100 gearing and using a 130/18 on the rear. OEM is 17/46 using 530 chain. The 17 lets the chain last a bit longer, the chain does not have to curve sharply as much, helps o-rings last longer.

FYI, the 750 because of lesser power uses a fifth gear that is closer to an overdrive, it is spaced away from the other 4 somewhat. Part of that also due to the different primary ratio off the crank. One can use a 900 or larger motor fifth gear and get a better fourth to fifth rpm drop like with racing, the spacing is more performance oriented.

 

[Macce88]

Today we put bike "together". Only 1,5 weeks to go before Finlands biggest motorcycle exhibition.
Lots of parts are now in place but fitment is something like "almost alright", if you now what I mean.

Front end not in its place, upper tripletree and speedometer is too high. Carbs are just hanging there and there is not enough room for middle airfilters.
Exhaust is not the one, which will finally be there. Shiftingrod is attached with zipties. Etc.

So we have less than two weeks to finalize as much of the parts as we can.
Main thing is to work on rear cowl to make bike look more ready and few carbonfibre parts has to fabricate.

Still here is few pics. Feeling much more satisfied when I look my project right now. Looking good for my eye












If you are in Finland between 2nd to 4th of February, visit Exhibition Center in Helsinki

 

[Wez_]

Out of curiosity, how did you extend your wiring harness to reach to the end of the bike frame? My wiring harness is limited by the length of the wires primarily the fuse box mounting location and the wires coming from it.

 

[Macce88]

Out of curiosity, how did you extend your wiring harness to reach to the end of the bike frame? My wiring harness is limited by the length of the wires primarily the fuse box mounting location and the wires coming from it.

We are going to do all wiring from point 0 to 100.
So I mean we are ripping every single wire out and put all new wires in.

We are also going to make much more simple wirings and get rid of few unneccesary wires.

More about that later

 

[Macce88]

Exhibition weekend was last week and it went great!
We had a blast!

Here are few pics from the event










Nice to see lots of people looking and talking about my own project...


As you may have already guessed, I didn't won in any class
Bike is way too unfinished, so we will have to wait until next year...

You also might note that rear cowl is looking like s**t.
I made it in one day from woodboards I thought that it will look pathetic if I don't make some kind of rear cowl.


Base is almost finished


Lots of grinding and some more grinding


This is the final shape and after that, I used filler, then some more grinding and finally put paint on it.

This will not be even close to what I'm looking for to do.



Also had a major backfire. From this picture you can see my problem


I don't have enough room for two middle pods, because rear shock has its capsule/container in the way...

Well I just bought new shock(s) and thinking of doing something uncommon... Stay tuned...




Today my friend is welding my sidestand shorter, because bike is way more lower than original, sidestand cannot be used right now.
He will also weld offset front sprocket.


Chain will be 530.
Old sprocket will go to turning machine (lathe) and it will remove all teeths from the sprocket. Also centerledges on both side will be shaved off.
New sprocket will have its one side centerledge to go.


After previous step, they will be joined together.


In two weeks I will receive my seat from upholstery. Can't wait to see it.
Next week my bike will go to mastermechanic, who will make custom exhaust for my bike. So it will stay in there about 2 weeks.


There might be a little silence in here for two weeks, but I will get back to as soon as possible

 

[Macce88]

I have question and I hope you guys could help me.
This might be very stupid, because I haven't done my homework/googling enough. Didn't find answer quickly...

What kind of options there is to upgrade DOHC engines eletronic ignition?
And does these thing have already electronic ignition?

 

[Odin]

This is what I will be adding to mine https://www.ebay.co.uk/i/292352827556?rt=nc

HTH

 

[Macce88]

This is what I will be adding to mine https://www.ebay.co.uk/i/292352827556?rt=nc

HTH

One in the link is suitable for earlier models, so SOHC engine only.

My question is about DOHC engine

 

[Dags]

Joined the forum to thank you for this progress commentary, photos and enthusiasm for your build.
Started reading and couldn't stop until the last post.
Have a similar build planned.....but so glad you have highlighted issues and alternate parts.
Many thanks again, looking forward to your updates.

 

[Macce88]

Joined the forum to thank you for this progress commentary, photos and enthusiasm for your build.
Started reading and couldn't stop until the last post.
Have a similar build planned.....but so glad you have highlighted issues and alternate parts.
Many thanks again, looking forward to your updates.

I'm really glad that my project thread is helping you!
Keep following!

Goal is to finish this project early summer (may/june), so I have hurry things up

 

[Macce88]

Bike is currently in a workshop for a custom exhaustsystem. Work will be done in mid-March.
Workshop will also fabricate plug for stopping oil spreading all over the engine from tachometercable hole (idk what it is called )

Before we took it there, we finished shorting the sidestand.




Shortened sidestand. Bike is way more lower than original, so it had to be done.


Welded little pin to the frame, which will stop sidestand hitting the frame. Have to buy a little rubberpiece end of it, so it will not scratch the paint




It came perfect


Friend of mine finished welding the offset front sprocket.


Looks amazing and works perfectly


Have to do minor work for the chainline. It is almost straight, but not enough yet


My seat came from the upholstery.


I'm digging it