Author Topic: 1969 CB750 Sandcast #4645 restoration  (Read 882 times)

Offline Spitfire

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #30 on: February 14, 2020, 10:22:28 AM »
What a fantastic journey, from it's "final" resting place to where it is now, pretty unbelievable, just shows what hard work, knowledge and skill can do.
Great to see another one being resurrected.

Cheers

Dennis
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

2000 NT650V DEAUVILLE

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #31 on: February 14, 2020, 12:05:24 PM »
There is no way this bike would be going back together in its correct, original form had it not been for Graham. All I can say is sorry, and thank-you mate :-)

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.

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #32 on: February 14, 2020, 04:47:02 PM »
What a fantastic journey, from it's "final" resting place to where it is now, pretty unbelievable, just shows what hard work, knowledge and skill can do.
Great to see another one being resurrected.

Cheers

Dennis
Thanks Dennis.

Offline Laverda Dave

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #33 on: February 14, 2020, 04:49:41 PM »
Great stuff James.  Are you actually going to be riding this gem or dedicating it to a museum for long term loan?
I must be blind as I am unable to see the photo with the hole in the crankcase?
1976 Honda 400/4
1977 Honda 400/4
1981 Honda CB250RSA
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1982 Laverda 120 Jota
1924 Triumph 550SD
2012 Stanley Battery Drill

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #34 on: February 14, 2020, 04:55:25 PM »
Great stuff James.  Are you actually going to be riding this gem or dedicating it to a museum for long term loan?
I must be blind as I am unable to see the photo with the hole in the crankcase?

Dave - was in one of the earlier posts. Hope you're sitting down.....

I'll definitely be riding this one....


Offline Laverda Dave

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #35 on: February 14, 2020, 06:19:56 PM »
Oh dear, and I thought that was all part of the air cooled motor!
1976 Honda 400/4
1977 Honda 400/4
1981 Honda CB250RSA
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1982 Laverda 120 Jota
1924 Triumph 550SD
2012 Stanley Battery Drill

Offline philward

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #36 on: February 14, 2020, 09:42:50 PM »
Great stuff James.  Are you actually going to be riding this gem or dedicating it to a museum for long term loan?
I must be blind as I am unable to see the photo with the hole in the crankcase?

Dave - was in one of the earlier posts. Hope you're sitting down.....

I'll definitely be riding this one....


Oops - that a hole! Wouldn't believe that could be repaired
Current Bikes:-
Kawasaki ZZR1100D3
Honda CB750K2
Honda CR750 Replica
Honda CB750K6 Cafe Racer Project
Kawasaki ZZR250 (1990)
Honda CB500K2 (1973) Project

Online Bryanj

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #37 on: February 14, 2020, 10:02:18 PM »
Like i always say anything is possible with time, money and a good engineer who really knows his stuff.
Just a problem getting all those in the same place at the same time!!!!

Offline UK Pete

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #38 on: February 15, 2020, 07:46:40 PM »
Amazing progress James, and trigger

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Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #39 on: February 16, 2020, 01:50:56 PM »
Like i always say anything is possible with time, money and a good engineer who really knows his stuff.
Just a problem getting all those in the same place at the same time!!!!
No wrong there Bryan. As I’ve said before, without Graham agreeing to take this on I’d have been stuffed.

Offline JamesH

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #40 on: February 16, 2020, 01:51:13 PM »
Amazing progress James, and trigger

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Cheers Pete - hope you’re well mate. J

Online Bryanj

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Re: 1969 CB750 Sandcast #4645 restoration
« Reply #41 on: February 16, 2020, 02:20:35 PM »
Thats what i meant Graham is a good engineer who knows hos stuff, anything 750 i defer to him!

 

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