CR750 replica build

[Sifu]

Absolutely amazing  : what a great read

[Oddjob]

Did you read the post on the USA forum Scott about the fella who restored a CR750 and got to meet Jay Leno as a result, Jay took the CR750 out for a spin and did a running commentary on it as he did so. Maybe when it's finished you could message him and see if he'd be interested in a better version of the same bike. The USA restoration was good but yours is better IMO. The CR750 ride etc appeared on YouTube IIRC.

[CR21]

Hi chaps,

Thanks for the kind words!

Oddjob - yes I remember watching that video - very cool.

Rear brake cable with works replica hardware complete:



Cheers,
CR21

[philward]

Glad you got back to it Scott! Fantastic quality of work.

[Rozabikes Tim]

Hi chaps,

Thanks for the kind words!

Oddjob - yes I remember watching that video - very cool.

Rear brake cable with works replica hardware complete:



Cheers,
CR21

Again stunning. What was the purpose of the small holes in the nuts? Lock wiring, surely not weight saving, or just to look mega cool?

[taysidedragon]

Almost everything on a race bike is lockwired Tim.

[Rozabikes Tim]

Low level club racing I did - sump plug, oil filter housing bolt, dip stick a few other bits. Whatever sure different with the high level stuff with the CR's,  just adds to the art in any case!

[JamesH]

Hi chaps,

Thanks for the kind words!

Oddjob - yes I remember watching that video - very cool.

Rear brake cable with works replica hardware complete:



Cheers,
CR21

Stunning as always Scott. How did you replicate the crimp finish on the cable ferrule? Did you have to make a specific crimp tool?


Sent from my iPhone using Tapatalk Pro

[CR21]

Hi Tim,

Yes for lockwire, many of the '970' parts for the CR had the provision for lockwiring, a must for scutineering in some places.

Thanks James - I was not brave enough to do the crimping so a local cable manufacturer helped out with that 

Cheers,
CR21

[CR21]

Another piece of the jigsaw for this build is the oil cooler, located underneath the headstock.

A extract from the ACU homologation files shows quite a small 3 core cooler:



I was able to borrow an original cooler which was super handy to use as a reference for the sizing and details, shown here at the back alongside some potential donor coolers. The temptation to use/adapt these is pretty high, however neither fit correctly which is a shame.



Unfortunately the donors are very close in style but are not suitable size wise.

Modelled up in CAD, along with the bracket which attaches to the original horn mount:



Machined nuts:




Currenly on the 3D printer for a fit check, I will attach the machined nuts and bracket to check against the frame



The plan is to engage with a specialist manufacturer to help out with this part, they will work to my 3D drawings once I am happy with the fitment - a tricky part to get right!


Also an epic shot of Dick Mann coming over the finish line at Daytona in 1970, this project is taking a while but I must keep reminding myself - the devil is in the details!



Cheers
CR21

[CR21]

3D prints came out well, ready for the fit check at the weekend, I think the tubes will need some adjustment. These basic prints are very cost effective, the material cost is around £2!





If I need to adjust the tubes I can warm up and adjust the prototype and then work that back into the 3D model.

Cheers
CR21

[Laverda Dave]

Amazing work yet again. How do you find the time to do this fantastic build!
I'd really like to see the finished article ridden by one of the magazines, get Alan Cathcart to test it👍.

[CR21]

Amazing work yet again. How do you find the time to do this fantastic build!
I'd really like to see the finished article ridden by one of the magazines, get Alan Cathcart to test it👍.

Thanks Dave - as I have other comittments and builds on it is super slow - my first post on this thread was in 2016!

That would be great - perhaps one day!

Cheers,
CR21

[CR21]

It has been a while since I did an update, and I am afraid it is only a small one!

Another piece of the jigsaw I have been working on is the oil cooler, a good friend who is also building a CR worked with me on this project to find a supplier, and with my drawing we had a small batch made, a couple of adjustments made during manufacture but I think they will do the job nicely, looking forward to trying them on the chassis. A surprisingly hard part to make/have made due to the specific welding/soldering required:


The 3D printed prototype, required some adjustments to the pipe angles before completing the drawing and sending to the supplier:






From the supplier:









The exhausts are a big part of the CR, I still intend on hydroforming my own but I have picked up some pipes during my hunt:

M-Tec exhausts, beautfiul quality and 'bolt on' but a little long/large for my liking:



Original CR exhaust, sadly only one pipe with a 'botched' header however it is very useful to have a proper pattern!



M-Tec exhaust left, original CR RHS:



Original CR, ignore the header:








I am just waiting for my hubs to be painted, the wheels are all booked in to be built.

Shocks, I managed to pick up some original shocks, kit items with 'forked' lowers and works items with eyelet lowers:



I am planning on running the eyelet type which require a modification to the swinging arm, part drawn in 3D, ready for machining:

]

Assembly drawing & historic image - credit to Nap!






Cheers,
CR21

[Laverda Dave]

It may be little progress but it is important progress. That oil cooler must have cost a pretty penny to have made, even the 3d prototype would be expensive to make.
Love the throwaway comment of 'managed to pick up some original shocks and some works items' I assume you didn't have to trade a kidney for those
Great to read an update, this is going to be a special bike when completed.