CR750 replica build

[CR21]

Everything about this build is impressive 
P.S. Can you do me some rear sets for a Z650

Paul anything is possible - send me a message and we can go from there 

[JamesH]

Stunning work (as always). This is going to be special...

[CR21]

Cheers James!

Seat, currently being made and shipped over to me. Beautiful attention to detail on this part, the 'studs' heat moulding on the seat and profile are spot on, I could not resist  At least this will allow me to finish the seat and tank mountings in one hit:





Cheers
CR21

[CR21]

Not as much done as the weekend as expected however, I am pleased with how the clamps turned out just got to work out the tubing interface now and the clearance of the master cylinder etc in order to get that right and repeatable I think I will build a jig.





Also the speedo drive adapter plate fits nicely:



Hoping to have a good session next month to finish the seat/tank mountings on and progress with the front brake etc.

Cheers,
CR21

[captaink]

Nice bit of machine work mate.
looking good 

[CR21]

Quick update:

Speedo adapter plate sitting in place nicely  Front end fitted with double disks. Really easy 'upgrade' as the fork lowers have bosses, it is just a matter of sourcing a 'mirrored' bracket, disk, caliper and carrying arm and bolting it on along with the modded speedo plate.





I still need to work out the hole drilling and skimming of these disks, and reevaluate whether they need shimming or not. I have read on a couple of forums that the set-up that I have done needs shimming, however as the caliper arms sit at the moment they are parallel to the disk, and I believe that they should function as intended.

To complete the 'front end brake set-up' I need to do the following:

- Create replica splitter block, cables to the lower calipers.
- Cable to the GL1000 master cylinder, with the mirror mount removed, or David silver can supply a very reasonably priced reproduction master cylinder which is suitable to drive twin calipers.

The 'original' bikes had a splitter attached to the horn mount, like below:



I need to look into thread types and spacing if I were to go down this route.

Another concern of mine is these original forks, obviously, my fork stanchions are only suitable for the bin, due to the corrosion at the top. These original forks are very crude and have been named 'pogo sticks' by other builders! A solution to this would be to have the lowers fitted with cartridges and then run reproduction uprated stanchions. It is of course also an option to go down the GL1000 front end, but I was not too keen on this.

Then, of course, it is building up the front wheel. I already have rims, but need to source spokes and need to skim the ribs off of the front hub to replicate the original cotton reel look that the original magnesium part had. I will have the hub vapour blasted and vibratory-polished to try and represent the original 'new cast' finish.

And of course the replica front mudguard, which is a small project in itself! I am planning on making one from an aluminum blade and fabricating the stays - a job for another time!

Extremely pleased with the seat unit, placed this onto the bike yesterday. I need to do the rear frame cutting, cross brace and hoop to accept this seat, and of course the brackets for the catch tank.



Lots to do, but glad the front end is underway!

Cheers!
CR21

[captaink]

Hi, I went down the GL1000 front end, twin disks etc.
I got a billet top tree from the states and powder coated black.
I got from Silvers a GL1000 master cylinder which can branch off to a splitter or as is fitted to my other CR bike a twin banjo at the master cylinder with a brake line to each calliper.
That front mudguard will be a challenge and I've yet to consider the options.. I'll be watching what you do as your trying to be as accurate as possible.

Your looking good though

[CR21]

Hi Captaink, thanks for the reply. Your build is great! Is the GL1000 front end heavy? Do you have any images of your splitter?

Yes the front mudguard is a detail that I really want to get 'right' not an easy one really though... Ideally I don't want to use fibreglass as well...

Cheers,
CR21

[CR21]

Quick update:

Went to Stafford on Saturday to meet up with people and exchange parts at the show! Usually I don't go to the April show, however I knew that a CR750 guru was going to be there. A bit quiet on the jap front as expected, this was a nice machine:



Picked up a lovely CR clutch lever and cable:



And also saw some extremely rare CR parts, the original TLS rear racing hub, as well as a single leading shoe racing hub. All genuine Honda parts cast in Magnesium:







My next thoughts is how can I go about replicating this hub, and a large chunk of aluminium comes to mind...

Cheers
CR21

[captaink]

Now that would be a challenge a complete hub ! 

I haven't made a brake splitter as yet, with your machining skills though that should be an easy one for you.
Honda sounds nice, my other CR Replica sounds like that, needs to tick over at 4000 rpm though, a mate of mine says he will take it round Brands for me, but he is an ex BSB rider with no fear.

Regards Keith

[CR21]

Now that would be a challenge a complete hub ! 

I haven't made a brake splitter as yet, with your machining skills though that should be an easy one for you.
Honda sounds nice, my other CR Replica sounds like that, needs to tick over at 4000 rpm though, a mate of mine says he will take it round Brands for me, but he is an ex BSB rider with no fear.

Regards Keith

Hi Keith,

It sure would be, that Is what I am aiming for... Nice!

Cheers
CR21

[CR21]

Quick update from today:

Spent most of today pondering about an oil tank  I must say it is certainly a challenge to get this thing in a sensible place!! The alignment is dependent on the breather routing, frame brackets and spacing, as well as the seat. Also the tank does not have any flat surfaces so that helps a lot 

Anyway, progress in images, added the frame brace, cut the frame at the back ready to accept the repositioned seat brace and new hoop. Tank in situ ready for some more thinking and lugging tomorrow 













Cheers
CR21

[philward]

Oil tank mounting has been my biggest challenge too Scott - still not 100% happy but its staying where it is now!

[CR21]

Phil - it has certainly been fiddly!!

A bit more progress from today:

Knocked up some hanger brackets and spigots, turned bosses for the rubbers to sit on, with a simple folded bracket; these accept an original Honda rubber mounting. Tacked in place for now to check the wheel clearance and hose runs at a later date. The lower brackets are still on the list!





Trimmed the rear brace from the frame offcut, this will be repositioned and lowered on the frame, the original Honda pressing was pretty poor so I took the chance to straighten the edge before it goes back on:





Folded up the rear tank strap mounting, I wanted to get a fair bit of stretch on the rubber to keep it strong on the mountings, having the double fold in the bracket provides more strength for the weld area. 







Onto the rear brake pedal. I bought a rough casting of an original brake pedal, this needed a lot of cleaning up and a bush pressing into it. The casting quality is not great, but probably reflects the era. Set up the pedal in the mill and skimmed the gate off of the casting, as well as facing off both of the bushing faces. Hole bored slightly undersized for an interference fit, heated the pedal to around 100 degrees and then pressed in the bush.



More heat needed!!



Pressed into place, lots of tidying up of the rough casting to be done:



Took the triple tree off and extended the lock stops.

That is all for now! The seat mounts I will machine up to get those smart as they will be difficult to fabricate from sheet material due to the tight double folds. Still got to do the following to the frame:

- Mirrored horn bracket for the oil cooler mount.
- Seat mounts and rear hoop with repositioned frame brace.
- Fit fairing and confirm front spigot location and angle.
- Lower oil tank mounts.
- Look into oil tank breather routing and catch tank.

Cheers
CR21

[philward]

Looking good Scott. Ref the mirrored horn mounting for the oil cooler - after I mounted the mirrored bracket, I had to make another bracket/plate to lower the cooler to avoid the cooler's exit's pointing at the side of the tank
Phil

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