Author Topic: 1969 CB750 Sandcast #4645 restoration  (Read 1650 times)

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #15 on: February 11, 2020, 10:25:50 PM »
Quote 'Graham made me sign a contract never to send him an engine like this again lol.'
Ah yes, not seen that come back in the post yet James
Ha ha - it was a verbal contract lol


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Ah, OK, suits me, less paperwork for me to sort



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Offline Andrew-S

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #16 on: February 11, 2020, 10:55:00 PM »
Stunning work.

I just love threads like this which raises what would have otherwise been a dead bikes from the grave. I'll be following progress with keen interest - always inspiring!

Bikes: 1970 US CB750 K1 and a UK 1976 Z900 A4
Cars:  1958 Triumph TR3A and a 1972 TR6

Offline JamesH

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1969 CB750 Sandcast #4645 restoration
« Reply #17 on: February 11, 2020, 11:02:37 PM »
Stunning work.

I just love threads like this which raises what would have otherwise been a dead bikes from the grave. I'll be following progress with keen interest - always inspiring!
Thanks Andrew, I appreciate it.

Online Bryanj

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #18 on: February 12, 2020, 01:03:15 AM »
Great work, am i tight that engine is lower number than frame?

Offline JamesH

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1969 CB750 Sandcast #4645 restoration
« Reply #19 on: February 12, 2020, 05:51:04 AM »
Great work, am i tight that engine is lower number than frame?
Yes Brian. I’ve had both higher and lower number pairs on sandcasts in the past..generally the engine number is higher...but it’s pretty random to be honest. During early production I think they fairly randomly selected engines from the line as they became available after quality control release..photo below is an excerpt from the Sandcast Owners public registry....I can’t see any discernible pattern..

« Last Edit: February 12, 2020, 05:56:31 AM by JamesH »

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #20 on: February 12, 2020, 09:46:27 AM »
Was looking at the frame again last night and noticed I’d missed a couple of ‘notches’ that the PO had made to the air box frame mount tabs. Annoying, but not worth stripping / repairing as it’s pretty hidden away under the tank (I’m telling myself it’s part of the ‘history’ of the bike lol).

Offline Moorey

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #21 on: February 12, 2020, 04:38:50 PM »
Nobody will see it at 100mph James.  ;)

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #22 on: February 12, 2020, 05:47:36 PM »
Nobody will see it at 100mph James.  ;)
Lol, true!

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #23 on: February 13, 2020, 10:07:08 PM »
Made some good progress over the past couple of days.

Centre stand, rear brake lever/mechanism and swing arm fitted, battery box and tool tray fitted, new rear shocks on, wiring loom loosely fitted, coils fitted, horn fitted, rider foot rests built and fitted, gear lever fitted, Honda logo on generator cover in-filled black, swing arm and headstock decals fitted.

She starting to show how good she’ll hopefully look when finished.

Paint set is off with Menno in Germany being painted (tank should be back from the chemical strippers tomorrow hopefully).

Both wheels have been rebuilt (original rims were rechromed several months ago before my supplier stopped doing them). Photos of those to follow (rolled rear rim is a beauty).

Rear sprocket carrier rebuilt with new bearing / retainer.

Exhaust collars have been rechromed and look superb, as do the exhaust spigots which have been refitted to the engine.

Anyway, enough waffling, here are some more pictures...


Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #24 on: February 13, 2020, 10:16:16 PM »

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #25 on: February 13, 2020, 10:27:44 PM »

Offline MCTID

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #26 on: February 13, 2020, 10:43:02 PM »
Yuk....the crankcases look a bit rough ! Before I bought one, I think I would have waited a year or so until Honda changed over to Die Casting them !

(Tee hee)
Now: CB750K4. 1970 Bonneville. 1979 Suzuki GS750E. Various other 1960's 650 Triumph T120's/ TR6's/ TR6C's. Previous: CB1300 (2). ZXR1200S. VFR800. CB750 Nighthawk. CX500. XS500 Yam. Suzuki GT500. BSA A10. Various Lambrettas. Zundapp Bella (honest).

Offline paul G

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #27 on: February 14, 2020, 08:21:52 AM »
Looking good as usual James  :)
Honda CB400 4
Honda CB550 K3
Honda CB750 UK K1
Kawasaki Z650 C2
Kawasaki Z650 cafe racer (ongoing)

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #28 on: February 14, 2020, 08:27:25 AM »
Yuk....the crankcases look a bit rough ! Before I bought one, I think I would have waited a year or so until Honda changed over to Die Casting them !

(Tee hee)

Ha ha yeah, I may have to get the sander out and smoothe them off..

Looking good as usual James  :)
Thanks Paul.

Offline Trigger

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #29 on: February 14, 2020, 09:19:20 AM »
I can't believe that you posted the pictures of that hole in the cases. I have just recovered from months of flashbacks and spent a small fortune on a psychiatrist to get my brain back in order  :o

A repair like this was even a challenge for me, it was not a case of wave a magic welding rod about and everything fell in to place. What happens when the chain whiplashes on the sprocket to make that size hole. The engine is hot and alloy of any type will reform in to a different shape. Think of a bit of hot alloy been hit by the force of a sledge hammer and you can imagine what the result would be  ???
First a jig was made from a 27mm plate so that the engine cases could be bolted down and measurements could be taken. Once I was happy that the cases are within spec ( not found in a manual ). You will have to try and fit the gear box, kickstart shaft and the final drive, while it is still bolted to the plate. Once you have worked out that your welding is clear of the gear box, you cross your fingers and hope for the best.

I lost count of how many times I removed and fitted the gearbox. As heat from the welding distorts alloy very easy. The welding took about 20 days, doing a little at a time, walking away for it to cool. Once all the welding was done the mating surface had to be milled taking a flat point from other parts of the case surfaces.

Job done after a little grinding and sanding but no, it was a little out of line on one of the gearbox bearing housings and a little line boring had to be called for before, everything lined up and fitted correctly.

 

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