Author Topic: CR750 replica build  (Read 32999 times)

Offline CR21

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Re: CR750 replica build
« Reply #90 on: May 07, 2017, 10:01:50 AM »
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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Cheers Phil!

Offline JamesH

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Re: CR750 replica build
« Reply #91 on: May 07, 2017, 10:10:04 AM »
Excellent work as always. Really enjoying seeing this come together. If you're considering going the DID alloy rim route drop me a PM. I have a few 3.5 x 18" DID alloy rims I've collected over the years and they look great with the GL1000 front 19" alloy DID rim. James

Offline CR21

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Re: CR750 replica build
« Reply #92 on: May 08, 2017, 08:23:15 AM »
Excellent work as always. Really enjoying seeing this come together. If you're considering going the DID alloy rim route drop me a PM. I have a few 3.5 x 18" DID alloy rims I've collected over the years and they look great with the GL1000 front 19" alloy DID rim. James

Thanks James, I will bare that in mind,
Cheers,
CR21

Offline paul G

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Re: CR750 replica build
« Reply #93 on: May 08, 2017, 02:05:14 PM »
Love this build ;D
Honda CB400 4
Honda CB550 K3 (sold)
Honda CB750 UK K1
Kawasaki Z650 C2
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Offline CR21

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Re: CR750 replica build
« Reply #94 on: September 13, 2017, 12:24:49 PM »
Just updated all of the broken links on this thread! Sorry about that  ::)

Offline CR21

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Re: CR750 replica build
« Reply #95 on: September 13, 2017, 12:25:03 PM »
Not posted on this thread for a while as I have been super busy, and also the 'top secret' Yamaha that I am working on is consuming a lot of my time, but its fun  ;)

Few small replica fixings sorted for the CR, plus a couple of spares of course:

Replica bolts for the master cylinder and the clutch bracket, with the very small lock wire holes!





Bushings done for the rear brake pedal:





Other miscellaneous bolts for various locations:



That is all for now, working away on a few details for this CR so it's all coming along just not as the usual pace :)

Also I need to get around to updating the links on this thread, it will happen soon  ::)

Cheers
CR21

Offline CR21

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Re: CR750 replica build
« Reply #96 on: September 13, 2017, 12:25:24 PM »
Just a quick update:

Had a fantastic time at the classic TT/MGP. There was a CR750 replica in the parade with a few trick bits on so I spent a while taking reference pictures of that. It sounded really rather nice going past the Conkerfields!

I believe that this bike is a replica, but it does have some genuine works bits on! Really handy as a reference  ;)

Me taking thousands of photographs as per usual:





Cheers
Cr21

Offline CR21

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Re: CR750 replica build
« Reply #97 on: September 13, 2017, 12:25:51 PM »
Quick update!

I have been super busy on the Yamaha project, but I have been working on a few small bits for the CR:

I have been working on a few small details, after seeing the CR750 over at the Manx, I decided that a custom throttle was in need. A dual-action push and pull throttle housing which looks "original" with the correct fastenings and adjusters. I have modelled this up in CAD, and will post some images shortly. I will most probably utilise an original or new throttle tube and will machine the other parts.

I have also been playing with the front brake splitter, this will be held on with a wire clip and a steel plate bracket. The T will be machined from solid aluminium, and the bracket and wire will be fabricated.



Another small detail is the works style fuel tap. Managed to get a starting point CAD model online, and to be honest the original design is pretty rubbish in terms of sealing. I think I will produce a version that looks like the original but has internals that won't leak! The TZ taps were pretty known for leaking as well  :-\

Here is the fuel tap body:







Anyway I wanted to test out some new technology, casting is something that has always fascinated me, I think it's the history around the process, and how good it can be as a production method. Loss wax casting, is where a wax model or plug is made of the intended shape, this is buried in sand or plaster with a vent and a sprue. When the molten aluminium is poured into the sprue hole the wax melts away allowing the aluminium to fill the cavity. This is a common method of casting relatively low volume parts.

However the difficulty and repeatability issues come when producing the plug from wax as you need a mould to create this plug.

3D printing technologies are moving on at quite a pace, and it's something that I am involved with on a daily basis, both designing and having parts 3D printed. A new material has recently been released which is a "castable" resin so I thought I would give it a try!

Here is the part as it has come out of the printer, you can see a "raft" the 2D shape on the table, and the "supports" the random pillars holding the object up. The raft and supports are removed leaving the plug.






The plan is to bury this model in plaster, leaving a vent and a sprue. This can then be cast for, or burnt out and cast from.

Of course after the casting process a lot of the surfaces would have to be post-machined to give suitable surface finishes for sealing and interfacing with other parts. And in reality the cast part would have holes blanked off, however for this stage I am interested to see what resolution is possible to get from a plaster casting.

Progress to come at a later date on the fuel tap front.

I have also made a small amount of progress on the clip-ons: tube interface parts being machined at the moment:







Due to the complex curvature, this part will start off as a piece of EN8 bar, will be CNC turned, and then added to the 4th axis of a Mill to 3D machine the complex geometry.

This enables the tube to be set at a repeatable angle, compared to the boss each time, this also gives a good engagement sleeve for the length of handlebar tube.

Cheers
CR21

Offline CR21

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Re: CR750 replica build
« Reply #98 on: September 21, 2017, 10:16:47 AM »
Quick update:

Tube bosses machined from EN8, ready for welding up:



Cheers,
CR21

Offline JamesH

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Re: CR750 replica build
« Reply #99 on: September 21, 2017, 11:12:14 AM »
Excellent progress as always.

Maybe worth reaching out to Richard (RGP750) if you need any advice on the casting process - he's been doing it as the 'day job' since before I was born ( :-) ). James

Offline CR21

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Re: CR750 replica build
« Reply #100 on: September 21, 2017, 01:22:35 PM »
Excellent progress as always.

Maybe worth reaching out to Richard (RGP750) if you need any advice on the casting process - he's been doing it as the 'day job' since before I was born ( :-) ). James

Hi James,

Thanks for that  :D

Thanks,
Scott

Offline CR21

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Re: CR750 replica build
« Reply #101 on: September 25, 2017, 05:59:31 PM »
Quick update:

Parts together and ready for welding. A quick side-by-side shot with an original HRC part:







I think I am going to make a second set of these from a high grade of Aluminium, as soon as I am happy with the design and fit.

Cheers
CR21

Offline Trigger

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Re: CR750 replica build
« Reply #102 on: September 25, 2017, 06:55:23 PM »
Nice work, fancy making some new cam towers  ;) Can't find a company that will do a small amount, everyone that has the correct CNC only do large orders.

Online philward

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Re: CR750 replica build
« Reply #103 on: September 25, 2017, 07:26:42 PM »
Nice work, fancy making some new cam towers  ;) Can't find a company that will do a small amount, everyone that has the correct CNC only do large orders.
I'm no expert Graham but in the 90s I had a Phil Read Rep with cam towers that where goosed - had them line bored and had some shells made for bottom of towers and complete new phosy bronze caps made that 'clamped' in the bottom shell's - not standard spec but worked for several thousand miles while I had it - hope that makes sense after several Madererian beers on holiday!

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Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Honda CB350K0 (1969)
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Kawasaki ZZR250 (1990) Project (Going on eBay ASAP)

Offline CR21

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Re: CR750 replica build
« Reply #104 on: September 25, 2017, 07:34:39 PM »
Nice work, fancy making some new cam towers  ;) Can't find a company that will do a small amount, everyone that has the correct CNC only do large orders.

Sure, drop me a message :)

 

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