Honda CB750 Sandcast

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Marcello Tha

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First of all i’d like to thank all members for their patience, understanding and apologize for my poor English. I started to get a Sandcast fever when i bought a K6 in 2012, imported from the USA. After a few months i saw a K0 (diecast), frame range  # 40.000, i became amazed by the beauty and rarity, there are about 5 or 6 of these in Brazil someone told me. The official import of the Honda CB750 in Brazil started in 1972 . I started looking for a K0 to buy, and a guy knew a person who had a Sandcast and maybe could sell . Sandcast, what the hell is it? I did a brief search on internet and for me there were only few differences between my K6 and the Sandcast, basically the wrinkle tank, double cut fender, four cable carbs, duck tail seat and of course the sandcast engine. How a sandcast arrived in Brazil (?), i’ll someday find out, one thing was certain, there was only one in my country and the best thing, the bike was in my town. I was informed that the owner attended every Sunday morning for a bike meeting in a local square, i got there at 10am and he arrived around noon. I went to the guy, a truck driver that used the bike every day, and asked him if the bike was for sale, he told me that his CB750 was not a common bike, was a Sandcast, was the only one in Brazil and discovered it when he made an advertisement for sale with some photos and hours later someone called asking his account number. At that moment I was glazed and asked what the price would be, and without hesitating he said " 90.000 " , I said " R$ 90.000 is too expensive ( approximately $ 40,000) for a bike in bad conditions like this " He replied , " noooo  U$ 90. 000 ", i asked him to open the tank and said, " your bike has no wrinkle tank and a double cut fender". A few days later i bought the bike, much cheaper than he requested but still expensive, equivalent to the value of my K6 restored, and in my account it would be cheaper than if i imported one (import taxes in Brazil are approximately 150% the value of the bike plus shipping). I thought it would be easy, just a few parts, some paint and i would have my Sandcast . Through SOOC i discovered that the restoration process of a Sandcast it’s not so simple and cheap. I gradually discovered that I had just purchased an engine a frame and a few original parts. I'm sure that, with the help of the members, my future mistakes will be corrected in time. Please, from now do not hesitate to point out my restoration errors.

Thank you.

Marcello Tha



Steve Swan

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Bravo, Marcello !  you are a welcome member !  To make you feel better, please look under General Discussion at my current project.........


Marcello Tha

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Grazie Steve, this is my K6.

Marcello

« Last Edit: November 30, 2013, 09:14:14 pm by Marcello Tha »


Steve Swan

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Marcello Tha

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The frame was in very good condition, was painted with 90% gloss black and than polished.



« Last Edit: November 30, 2013, 09:16:39 pm by Marcello Tha »


Marcello Tha

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A beauty !  You'll really enjoy riding the sandcast.  Really a very different running/riding bike than any K2-K6 !

Steve, my fear is that the Sandcast become so beautiful that I did not want to drive it. I know that the K6 will end up getting neglected by the Sandcast or by the CBX1000 1978 that I'm also restoring.


Marcello Tha

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The cylinder and head are ready to be assembled. Pistons, rings, bearings and valves are new, as well as all the chains. I chose to leave the engine again with standard measures. The pistons were measured in 0.50mm and I also had to buy a new crank in good condition, with luck found one with only 5000 miles. The engine owned signs, thankfully only internal, that the chain had broken at some point, which took some of the former owners to change the gear to 18 teeth, put back an original Honda 17 teeths  gear.

Thanks to Joseph T. Marks for all Honda original parts.

Marcello





« Last Edit: April 12, 2014, 01:57:07 am by Marcello Tha »


Marcello Tha

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Production dates:
Crankcase 8/22/69. Oil pan 8/14/69.

Where can i find more dates?

Marcello




« Last Edit: November 30, 2013, 10:21:34 pm by Marcello Tha »


Marcello Tha

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Some of the key parts that had to be changed arrived from YAMIYA, as short chain cover, seat, side covers, no number pipes and DUNLOP tires (f11/k81). Other parts came from various U.S. suppliers, as front disk and the valve breather that shows an amazing original finish. My shocks were from a K2-K6, than i bought a new pair of K1 shocks and a used pair of K0 shocks and will change the coils to have a correct pair. My biggest question today, about my original seat is if I replace, other than the original cover by the Yamiya cover the original foam by the Yamiya foam or keep my original foam.

Thanks.

Marcello

















« Last Edit: November 30, 2013, 10:20:34 pm by Marcello Tha »


Marcello Tha

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Last week my mechanic started the engine mount. The green bearings nicely fits the Honda specifications. The standard Honda bearing clearance is 0.020 to 0.046mm and my measurements were close to 0.030 mm. My surprise was to verify that he had not painted the cylinder and he explained that all K0 that he saw or restored in Brazil had the cylinder and the head with a natural finish. I showed him other SOOC members restorations and this myth has been clarified.

Marcello



« Last Edit: April 12, 2014, 01:28:12 am by Marcello Tha »


Marcello Tha

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I Reproduced the Candy Blue Green perfectly at a DuPont dealer, based on my airbox, who owned the original paint.

Below is the formula to be reproduced, I believe the codes are internationaly the same, and can be redone.

BASECOAT (polyester for 0.45 liters)

DX 36: 10.00 grams
DX 24: 0.65 grams
DX 27: 1.65 grams
DX 54: 10.00 grams
DX 34: 8.00 grams
DXBP: 350.00 grams

MIDCOAT / CLEARCOAT (polyester for 0.45 liters)  

DX 24: 15.00 grams
DX 25: 2.00 grams
DX 28: 6.00 grams
DX 09: 0.50 grams
DXBP: 380.00 grams

1 pound = 453.59237 grams


Marcello









« Last Edit: November 30, 2013, 10:39:43 pm by Marcello Tha »


Marcello Tha

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The parts arrived from painting, the work quality seems great to me, only one ear and my original airbox are being redone. The hue appears bluer on photo than naked eye.

Marcello







« Last Edit: November 30, 2013, 10:30:58 pm by Marcello Tha »


Marcello Tha

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I'm trying to repair the sprocket cover and transmission cover that were welded and in these places were very porous (holes). I did the welding and sanding process several times and new holes are appearing, I bought a really sandcast mission cover on ebay, just like my old one,  simultaneouslly  I'll retrieve it. The sprocket cover had the same problem and internally was changed for placing a chain guard, yesterday a member offered to sell me one in good condition, thanks for him.

Marcello

« Last Edit: November 30, 2013, 10:32:45 pm by Marcello Tha »


Marcello Tha

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 :-\
Help me please.

Someone could confirm if the oil tank bolts (90141-300-000) are really yellow zinc plated?

Marcello





« Last Edit: November 30, 2013, 10:24:24 pm by Marcello Tha »


CBman

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Yes, these should be yellow zinc plated.