Honda CB750 Sandcast

Restoration of Sandcast #97

markb · 814 · 327026

UK Pete

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Thats amazing mark, i have tried my hand at aluminium repairs and know exactly how tedious it can be , the way to go with this sort of stuff is do a bit at a time, each time you come back to it you have a fresh look and enthusiasm, which soon goes ha ha
Pete


kp

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Great job Mark I'm impressed indeed  :o KP
Yabba Dabba KP


markb

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Thanks guys.

I know I’m jumping around a bit but towards my goal of getting all of my polished aluminum done I tackled the front forks so I could get the lowers off.  They actually came apart easier than I expected and look pretty clean inside.  The seals look really good so I think they must have just been replaced before it was parked.  They will get replaced of course.


There was a sticker on one of the lowers.  It’s a little hard to make it out but at the top it says Oklahoma and the bottom shows that it was last inspected (and presumably ridden) in 1979.


I took the tubes out of the lowers so I can clean everything inside easier.  Notice the special screw and washer.  It’s a good idea to replace the washer to prevent oil leaking out the bottom.  Guess how I know that?  They are not shown in the Honda parts manual but they are both available from Yamiya.  The washer is part number F146 and the screw is number F147.


There was what looked like wear on one of the pistons.  They are discontinued but I measured it and it was 1.552” diameter (above the serviceable limit of 1.551”) and it was round and straight within spec too so I’m using it.  The springs were well in spec too so I’m going to use them too.


All these little rings are also discontinued so I veeery carefully removed them.  They are all very similar so I measured them and recorded the sizes in my parts manual so I wouldn’t mix them up at reassembly.

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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As usual, great work, Mark.  Thank you so much for sharing.

232's steel legs were surprisingly badly pitted and rusted, nothing that could be cleaned up on the lathe.

I had to replace them.  Since they are nla from Honda, i had Forking by Frank in Chicago make a set.  Frank's has been around since the early-mid 60's.

a trick we use at my friend's m/c repair shop, in cases where there are less than a few small pitted areas, we use JB weld and then clean up the leg on the lathe.  Never had JB weld repair come back.  I realize, of course, we are restorers, so a repair like this seems crude.  None the less, an effective and easy repair.


UK Pete

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All my fork bits are now mixed up so i might have to pick your brains about what bits and what sizes go where and what way round etc
I usually tear things down then stand back and thing why didnt i pay more attention to what goes where
pete


kenhan

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I´m a little puzzled about the partslist concerning this. I have reassembled 2 early front forks and they both had that pipe Markb referring to regarding screw and washer. In the partslist the pipe is described only as a K2-part and is totally missing for the first two pages of front forks. As it is a K2 piece, Honda is delivering both screw and washer.

When I was restoring the front end I took some pictures that describe the order for the rings. As I can recall I think the second ring should change place with the shallow piston ring to be correct, otherwise it should be in this order.

I attach some pictures regarding this.

/Ken
1969 CB750 Sandcast #5084 - running
1969 CB750 Sandcast #5128 - Running
1970 CB750 next project
1975 K2 (K3-5 don´t exist in Sweden) - Running
1981 Goldwing 1100 Interstate


Steve Swan

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My recall on 69-70; which exact fork parts are interchangeable with 71-onward is a bit fuzzy.

What i am certain of is, certain 1969 type fork internals including legs do not interchange, won't fit 71-onward fork internals.  In other words, you can't mix 69 parts with 71 parts to build a set of forks.

IF i recall correctly, sandcast/"K0" internal parts are all the same.  Beginning K1, internals were changed for better dampening characteristics, more and different parts were added.

Our friend Chris Rushton can recite these details from memory.  My self, to recall the differeneces, i would need to look up my notes as well as compare 69 parts book with 71 parts book to see which parts these models share in common and which parts are different from each other; i.e, what will interchange and what will not.



markb

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Ken,
Interesting about the screw and washer.  I checked some later parts manuals and you're correct, they are listed.  Good to know.  The pipes were included as part of the lower cases on earlier models.  
Ken & Pete,
My wire rings were in the order shown in the second picture.  The top most ring was .070 diameter.  The next ring down was flat .048 thick.  The third one down was .054 diameter.  The bottom one is obvious.  If I look close in my early part manual it looks like that matches.
If you look at the parts diagram from the K0-K2 parts manual shown below the top three are (top to bottom) numbers 9-12, 11 & 12.  The quantity for item 9 is 2 for the K0 and 0 for the K1-K2.  The quantity for item 12 is 2 for the K0 and 4 for the K1-K2.  So it appears that item 9 is only used on the early model.  
By the way, the damper ring, item 8, has a chamfer on the inside that goes down against item 12.
Does any of this make sense?
Mark
« Last Edit: December 23, 2012, 01:14:49 pm by markb »
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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So now what to do with the tubes?  The top halves of the tubes are pretty rough.  The bottoms were OK and no one would see how bad they are but I would know.  I considered having them built up and reground but decided against it.


I also considered tubes from Yamiya and Forks by Frank but fortunately I was able to score on two Honda NOS tubes.  I had to buy them from two different sellers but I can’t believe I found them.


I was a little concerned that they might have some surface rust on them but they were clean on the outside.  What little there was on the inside cleaned up nice when I stuffed an oily rag through them.


I inspected them carefully and they match the originals exactly.


I decide to put them together before I misplace any of the parts.  Here they are all assembled.  I oiled them up real good on the inside and outside and wrapped them up to put away until I need them.  It feels good to actually get something put back together.

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?)


UK Pete

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Mark i have the same with my forks, i still cant decide what to do, my trouble is i have run out of money, and worse than that i have no work so, it will be a struggle to afford anymore new parts for quite a while
Pete


markb

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Pete,
Sorry to hear about your situation.  You're sure doing a nice job on your project.  Maybe Santa will be good to you this year.  ;)
I'm sure I could have cleaned mine up (although they still would have been badly pitted).  But functionally they would have worked just fine.
Mark
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 another little project done.  This is probably the ultimate in anal but I’m glad I did it.  Remember my rear brake panel with the notch broken out?


I wanted to rescue it because it is different from later sandcasts.  It’s the only one I’ve seen like it.  The one on the left is from #97.  The one on the right is from #1553.  Notice the 4 round areas on the ribs near the center hole of the later one.  There seems to be some subtle differences on the outside too but nothing distinct.


I had my welder use some of my homemade welding welds to fill it in hoping the color would match.


Then I made up a fixture so I could put it on the mill and machine the OD and backside.  This is after machining.  I was tempted to use a burr and try to remove some of the extra weld to make it look less like it was repaired.  I still might.


And here’s the outside.  I did it all with a file and sandpaper.  Very tedious.  Still a lot of polishing to do on the rest of it but I think it turned out great.  You have to look really close to see it.  Me and you guys are the only ones who will know that it is a special, early, rare sandcast part.  But that’s part of the satisfaction of it.  :)

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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Mark, great observation on the 4 round areas of the backing plate !  Make me (almost) want to remove the rear wheel on 232 and see what's in there !  It's really great you have the later vins to compare parts to !  4363 came first to me, what was there appeared original to bike, by the time i had 232, 4363 was restored, so nothing to compare to.  2157 came after 232 was restored, so again, nothing to compare these finer details to... :'( The one distinction of 232's rear sprocket carrier, which i believe we've discussed in other posts, was the 4 bolts fixing sprocket to carrier, these bolts had early "8" on the face of the head.

I'm so glad you are able to take the time to compare parts.  Being anal is what restorers like us do; it's careful observation to documenting what we believe correct for a particular vin production run.

Would say the details on the inside of the backing plate on 97 should go on the distinctions list.... ?

Seems it's easy to lose these distinction in posts which, in some cases, tend to get buried in the BB..

If you guys think of it and have the time, would you shoot me an email, that way i will be sure to get them in the "Distinctions" list.   :)


markb

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I’ve been procrastinating what to do with my rear driven flange.  It has deep grooves worn in it from the chain guard.


In the worst areas they may be up to 0.5mm (.020”) deep or more.  Hard to believe that a plastic chain guard could cause so much damage.  I considered using the one from #1553 but it wasn’t much better.  And since this is a common problem it’s not likely I’ll find an early one without gouges so I decided to try to save it.


I was tempted to put it on the lathe but in the end I did it all with files and sandpaper.  I took a couple of hours but it turned out great!  I still have plenty of work to do but the hard part is done.


While I was working on it I noticed something interesting.  There are three center punch marks on the hub.  Anyone know the significance of that?  Maybe an indication that a recall was done?  Since this is a restore should I remove 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?)


cb7504

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Mark: I would not remove the three punch marks as they are part of the history of the bike indicating service bulletins have been complied with on this particular vin. Marty K.