Topic: trying to buid a CR 750 look alike

[Sam Green Racing]

I hate electrics

Sam.

[silvercr750]

Me hate electrics too Sam
It was the least job so far.

[silvercr750]

More electric.

drawings, connectors, wires etc.

By silvercr750 at 2010-02-21

But at last it worked and it became a nice small piece of work.

By silvercr750 at 2010-03-01

All hard parts are under the tank, included the battery.

By silvercr750 at 2010-02-15

[silvercr750]

I don't see many caps in 1970.

In Mallorca I gave myself an nice CR cap.

By silvercr750 at 2010-07-01

and a shirt

By silvercr750 at 2010-07-01

see you

[silvercr750]

Hi there,

After all the electric came the wheels.
Bought me a pair of nice "Hochschulter" rims

By silvercr750 at 2010-06-12

In the rear comes a Light weight magnesium brake

By silvercr750 at 2010-06-12

All spoked it looks like this.

By silvercr750 at 2010-06-12

[silvercr750]

These disks come from an early Fireblade 295 mm.
Some spacers have to be made later on.

By silvercr750 at 2010-06-12

And offcourse a Bridgestone tyre.
They supported us while racing and it's a good tyre.

By silvercr750 at 2010-06-12

With the rearwheel in place all the works on the rearfork turned out to look just good.
This way the wheelbase is shortend by 4 cm and the tyre has just enough space to turn free.

By silvercr750 at 2010-06-12

[754]

Cool project, not sure what swingarm you cut? not CB750.

 The bike you started with.. over here that is called..

 a StreetFRIGHTER...    

[silvercr750]

Hi Oldtimer,

Yes a streetFRIGHTER it was.
Hopefully in the end this will not be seen.

The swingarm came out of the streetfrighter, CB750 K6

[voxonda]

Definitely not a CB 750 SOHC swingarm! By the look of it, it is a DOHC 750/early 900 swingarm.

Cheers, Rob

[silvercr750]

I find it an classic looking swingarm.

In my stock I also have a box-like swing so I can switch any time.

Now for the build.
I had decided to get some 4-piston brakecalipers.
Via Ebay I bought 2 Calipers and 320 mm disks.

Now I had the frontbrake together, I thought.
"Only" a bracket had to be made.

BUT when I installed the frontwheel with the disks the caliper did not fit in and the spokes hit the caliper on the back.
GGGGRRRR  now what??


By silvercr750 at 2010-08-29


By silvercr750 at 2010-08-29


By silvercr750 at 2010-08-29

[754]

You might be able to grind some off the back of caliper..& or mill a bit off the mounting surdface.. Check thickness. Are you able to move the discs outward?
 Newer wheel designs are thinner in the spoke area.

[silvercr750]

Hi Oldtimer,

Indeed the newer wheels are smaller.
The disks are 4 mm from the frontfork so no possibility to move them further outward.
 
An other solution had to be found.

As I also wanted to shorten the front fork for a better handeling in corners.
I tryed to lower the stock fork 2 cm. But even then the innerforks would stick out on top.
Now my eye fell on a Honda NSR250 frontfork.
Some guy offered a complete fork with brakehandle, steel barkelines and calipers for 100 euro.
 
Luckely this fork fitted right in to the frame.
Nothing needed to be remade I could stick it right inn.

And this fork is a hole 5 cm shorter then standard the frontangle is better for cornering.


By silvercr750 at 2010-06-21


By silvercr750 at 2010-06-21

[754]

Do you have to run wire wheels? or wheels of that period? Yamaha mags from that era are correct bolt pattern for Honda discs and may be thinner where you need caliper clearance.

 The new fork NSR250, how much did the bike weigh that it is from, just being careful..

 Stock CB 750 forks the 77/78 F and K trees have less offset and 550 4 has an even different offset, they should work with 750 forks, if you do end up using them.

 Shortening forks in a lthe will get you the length you want..

754

[silvercr750]

Hi 754,

I must not run wired wheel but I like them better in this bike.
I suppose a NSR 250 is about 50 kilo lighter then my 750 in the end. So a few heavier springs will be installed.
 
And yes the offset in the trees is diverent, I have both models.

Here are the ones I would have used if I stayed with the 35mm fork.
The upper tree went from here;

By silvercr750 at 2009-08-03

To here;

By silvercr750 at 2009-08-13

Till here;

By silvercr750 at 2010-08-29


There is also a diverent is offset between the frames I had.
The black frame is out off the K6 and the grey one is from a F1

You can see the frames are lined-up the same but the angle is very diverent.
This is why I chose the black one.


By silvercr750 at 2010-08-29


By silvercr750 at 2010-08-29

[silvercr750]

So where am I with this build so far.

The frontbrake now is a 3 piston Honda.
This way there are no problems with the spokes. It is a 200% better brake then original.
And together with the NSR frontfork it relatively easy to install.

Thes are the brackets that are being made right now.

By silverCR750 at 2010-08-30


By silvercr750 at 2010-08-18

In the meanwhile I found a guy that builds fairings himself.
After looking for a good one this was my best find sofar.

He also wants to make the tank with Monzacap.
It will be a Polyester tank and he says there will be no problems with modern fuels inside and paint outside.

[silvercr750]

Just a pic of the fairing.

By silverCR750 at 2010-08-30

[Sam Green Racing]

Looks like a copy of the Airtech one.

Sam.

[kos]

Looks like a copy of the Airtech one.

Sam.

Good one to copy or purchase from Airtech as those are the real versions. Taken from my original fairing that I sent them.

Expensive to ship overseas, but the right one.
Mk

KOS

[napoleonb]

Mark,

Me and a friend of mine bought simultanously from Airtech but those (both) didn't fit and were quite off in quality.
They differed also between the two of them...

But I am sure they match the original as close as it gets.

[silvercr750]

Hi there,

I surely would have bought the Aitech fairing alltough they cost aprox 600 euro when they are delivered here in Twello.
This would mean I should have to save a few euro's first.
Now the price was less than half. And a good quality and it fitts very well.

Mark,
Very good to read how a part is born and lives on.
The original one is copied. The copie comes to Europe and gets copied overhere.
Now we have (almost) the same parts in Europe as in the US of A.

The same will be done to the seat.
And I hope many more parts will get there replica at the other end of the world.

The brackets for the frontcalipers are being handmade now.
So is the upper mounting for the rear Koni-shocks


By silvercr750 at 2010-08-30

[Howell]

In the meanwhile I found a guy that builds fairings himself.
After looking for a good one this was my best find sofar.

He also wants to make the tank with Monzacap.
It will be a Polyester tank and he says there will be no problems with modern fuels inside and paint outside.

Hi Coos,

For my CB750 I bought this summer also a CR750 replica tank from polyester , because my very old polyester tank from the seventies was leaking.
The seller told me that the tank was resistant against all fuells.
But that was a big mistake , after 200 km with this tank the throttle valves kept hanging.
The resin from the inside of the tank was solving and left a sticky stuff on the throttle valves and in the cilinder intakes.
Now the tank goes back to the manufacturer to examine why the resin solves.
I told them that I want my money back , never again a polyester tank !!!!!
So I warn you , this is the second time I have problems with polyester tanks

gr.René

See the brown sticky stuff:

[silvercr750]

Hi René,

I've heard of the problems with the polyester tanks.
There for I also wanted a aluminium tank.

But;

This tank will be made as tanks in boats are made.
These are also made of polyester.

By hand the inside will be painted with a sort off protection.
This will save the polyester from the modern fuels.
The fuel will not penetrade the polyester and distroy the paint.

We'll see and I trust the builder of these tanks and keep you all informed how this ends.

gr
Coos

[silvercr750]

So back to the brakes.

The brackets are back and ready to bore the holes for the bolts
They need to be grinded and polised.


By silvercr750 at 2010-09-01

And the rearshock could be placed and now the bike can stand on it wheels for the first time.
On the pic it stands on the front standard but I couldn't help sitting on her for a few seconds.

Real racy position. Clip-ons far away and footpegs high in the air.
Like it very much.

By silvercr750 at 2010-09-01

Big smile on my face this evening.

[754]

Silver, are you making those brackets without a milling machine.. Ie drilling, grinding, & sanding? If so. good for You..
 Nice to see someone that does not say cant!

 If you need asdvice on making it the hard way, with very few tools... I may be able to help..

[silvercr750]

Hi there 754,


As my grandma just to say; 'cant' lies on the graveyard, and 'won't' lies aside.

Yes I'm trying to make as many as possible parts by hand.
I know with a laser-cutter you get very nice lines but I prefer to do it by hand.

Also the upper tree is sawed, grinded, sanded and polist by hand.
This way I think the bike becomes more from yourself.

I get a little help from an older man who has lots of experiens with metal.
He also works on Bugatti-parts that are shipped from the US of A to Twello for a surface treatment.

But all the advice I can get is welcome.
Do you have some tool-advice for me for a better result?

Looking forward to hear from you.

This is my hand after a few hours of aluminium work.

By silvercr750 at 2010-09-02