Honda CB750 Sandcast

Restoration of Sandcast #97

markb · 814 · 285338

markb

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Speaking of "8" bolts........  Are your 4 special shouldered 10mm bolts fixing rear sprocket to the carrier, "8" type ?  
Steve, I've been meaning to answer your question for a while now.  Yes, they are the "8" type.
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


Steve Swan

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Cool !  Your carrier bolts are the 2nd set i've heard of being #8's.  I was really surprised to find them on 232, when i took it apart.  Considering all 232 has been through, it doesn't cease to amaze me.  So many of the small parts were still present despite two engine changes after leaving the factory and some event that tweaked the steering neck.  I the remains of the original engine came in boxes, as well as early carbs and the rear (round bead rim) wheel with those special "8" carrier bolts.  I feel very fortunate.  I am not aware of any vin higher than 232 that has these "8" head bolts.    Am guessing 232 is nearing the last of the vins to have these bolts........

Would be neat if someday we could categorize the distinctions in vins by every 100 numbers through 1000 or perhaps 2000............


Wayne

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Speaking of "8" bolts........  Are your 4 special shouldered 10mm bolts fixing rear sprocket to the carrier, "8" type ?  
Steve, I've been meaning to answer your question for a while now.  Yes, they are the "8" type.


Where are we looking here?
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Steve Swan

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What is shown in this picture is the one of four "vanes" as seen on the inner aspect of  the sprocket carrier which is positioned on the LH side of wheel.  The "8" bolt goes inside the vane, through the carrier from the inside with the threaded end protruding through the carrier's outside and through  one of the four bolt holes in the rear sprocket.  The threaded end gets a 17mm nut, as do the other three threaded ends of the 4 bolts.  Sorrrrry, i always tend to get too wordy.........  :D

These carrier bolts with "8" are rare, as far as i know.  I don't know of a vin >232 that has this "8" head on the sprocket carrier bolt.



markb

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Yea, what Steve said.  ;)
It would be fun to know it the recently sold #244 has them.
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


markb

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I got my cases, crank and oil tank back from the hot tank and ultrasonic cleaning.  They didn’t come out as fresh looking as I hoped but they are definitely cleaner and all the holes look great and the inside of the tank looks good.  I’m satisfied that all the oil galleries are clean.


You can see that the inside of the cases still has that brownish, stained look.  But it’s nice to be able to handle them without having to wipe my hands off afterwards.


I do have another issue though.  Upon closer inspection of the oil filter housing surface, there is some pitting at the bottom.


Here’s a closer shot.  Hard to see it well.  I’m obviously concerned about the o-ring sealing properly.  My first thought was to apply a thin layer of JB Weld with a putty knife to fill in the pits and then flat file it to make sure it’s smooth.  Anyone else have this issue?  Any thoughts?

Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


hondasan

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I too would be concerned about possible oil leaks and so would use either an instant metal or other epoxy compound to smooth / fill the pits.

That "brownish stain" inside the cases is likely the remains of a factory "coating" which was applied inside the cases to seal the surface (#338 and #1106 have the same coating) - there were allegedly problems of porosity of the sand cast cases.

Cheers - Chris R.
Chris R.
302/338


kp

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I too would be concerned about possible oil leaks and so would use either an instant metal or other epoxy compound to smooth / fill the pits.

That "brownish stain" inside the cases is likely the remains of a factory "coating" which was applied inside the cases to seal the surface (#338 and #1106 have the same coating) - there were allegedly problems of porosity of the sand cast cases.

Cheers - Chris R.

Another 10 points to Chris for that info. KP
Yabba Dabba KP


markb

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What about filling it with weld then machining it off?  Personally I'd have concerns about that but just checking.
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)


Wayne

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What about filling it with weld then machining it off?  Personally I'd have concerns about that but just checking.

I was thinking the same thing Mark. I think a good welder could tig that up for you without generating too much heat and or problems. That would be problem solved forever.
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Riccardo

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What about filling it with weld then machining it off?  Personally I'd have concerns about that but just checking.

I was thinking the same thing Mark. I think a good welder could tig that up for you without generating too much heat and or problems. That would be problem solved forever.

I agree, i think that this is the resolutive way.
Riccardo
Your Italian friend.
737/940 Restored
1081/1362 Preserved
1256/665 Restored - ex Owner: Chris R.
10253/10315 (K0) Next project
1969 - Kawasaki H1 Mach III low ign cover - Restored
1969 - Kawasaki H1 Mach III high ign cover - Restored
1971 - Kawasaki H1A - Restored
1973 - Kawasaki H1D - Preserved
1973 - Kawasaki Z1 Blackhead - Restored
1971 - Norton Commando SS - Preserved
1978 - Honda CBX - Unmolested Museum Quality
1988 - Honda CB 400SS - Unmolested
1997 - BMW R80 GS Basic - blue frame - Museum Quality
2007 - BMW HP2 Megamoto - blue frame - New


markb

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I don't think the welding is the problem.  Getting it fixtured on a milling machine and getting it machined flat is more of a challenge.  My company has a machine shop and the machinists here don't want to tackle it.  I have quite a few resources I can check before I make a decision.
Mark B
1969 CB750 sandcast #97 restored - Sold Restoration thread link
1969 CB750 sandcaxt #576 - Sold
1969 CB750 sandcast #1553 - Sold
1969 CB750 sandcast #1990 - Sold
1969 CB750 sandcast #5383 restored - Sold Restoration thread link
1970 CB750 K0 restored - Sold
2010 H-D Tri Glide Ultra Classic (Huh?)



Riccardo

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I don't think the welding is the problem.  Getting it fixtured on a milling machine and getting it machined flat is more of a challenge.  My company has a machine shop and the machinists here don't want to tackle it.  I have quite a few resources I can check before I make a decision.

Yes, after the welding fase is necessary a turner job (with a special tool - probably a stone with a central hole) to create again a perfect base for the bottom face of the oil filter cover.
Riccardo
Your Italian friend.
737/940 Restored
1081/1362 Preserved
1256/665 Restored - ex Owner: Chris R.
10253/10315 (K0) Next project
1969 - Kawasaki H1 Mach III low ign cover - Restored
1969 - Kawasaki H1 Mach III high ign cover - Restored
1971 - Kawasaki H1A - Restored
1973 - Kawasaki H1D - Preserved
1973 - Kawasaki Z1 Blackhead - Restored
1971 - Norton Commando SS - Preserved
1978 - Honda CBX - Unmolested Museum Quality
1988 - Honda CB 400SS - Unmolested
1997 - BMW R80 GS Basic - blue frame - Museum Quality
2007 - BMW HP2 Megamoto - blue frame - New