Honda CB750 Sandcast

Restoration of Sandcast #97

markb · 814 · 285440

vnz00

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Hi Mark,
I had some imperfections weld filled on my K0 top case where it mates with the barrels. The weld was simply dressed with a file back to a flat surface. Provided it is smooth and level the gasket will take up the rest.

The bottom (where the weld will be exposed once the filter is installed) can be dressed with a die grinder and lightly sand blasted to render it invisible....

Regards Steven.


markb

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Mark, does your rear wheel hub have holes in it ?  steve  

Yes, 2 holes.

Steve, any thoughts about repairing the oil filter housing mating surface?  It looks like the consensus is about 50/50 to weld and machine or JB weld-type fix.
« Last Edit: February 07, 2011, 09:00:54 am 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?)


Steve Swan

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i know from experience JB weld does not work very well for patching holes in the junction area of exh.pipe to muffler.  it tends to run as well as begin to bubble as if in blowing out, the JB weld patch with mesh was about 1/8" thick.  Did this repair on all 4 HM100's on a K1 i had.

BUT, this area on the crankcase does not have any of the same pressures or temps.   The only thing i could have concern about using JB weld is heat + time + oil affecting the JB weld, which is unlikely and can always be replaced.  

I was impressed with the Alvin Products link Donzie sent.  http://www.alvinproducts.com/  The product is designed specifically for heat applications.  If a non-ferrous repair is to be applied, i would use the best product i could find.  

I am sure JB weld would be fine, but the Alvin product is designed for heat.

Not sure one needs to go to the trouble of welding/machining, considering what type of service condition the repair will be subjected to.  The welding would be no problem.  It's getting the case set up on the table of the mill to get the weld repair parallel to the table to mill off the weld that will be a major task.

I vote Alvin Products.


markb

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Thanks, Steve.  I'm kind of leaning that way. 
While I知 thinking about how to fix the case, I知 getting everything black ready for the painter.  I know it will be months before I値l be ready to use it, especially on the frame, but I want to prevent any additional rust.  While I知 at it I知 going to send both of my frames out.

I always remove any bushing or bearings before the paint.  Here痴 a pic of a tool I made that I use to remove the rear bushings of the swing arm/rear fork.


You can do the same thing with the right sized sockets and some threaded rod and some nuts but if you致e got the resources to make one it works great.  It also works as an installation tool.

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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Checked out the Alvin Products link.  Are you saying I should use the Lab-Metal or the High-Temp Lab-Metal.  At 400 degrees I would think the regular Lab-Metal would be adequate.
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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Going by Alvin website, i'd say the Lab-Metal should be good.  I cannot imagine the crankcases ever getting much over 300'F on the hottest days.  Cannot remember for sure, but seems JB weld upper temp applications was 250'.  And, for sure, the exhaust system would be several hundred degrees under normal operating conditions.  Seems Lab-Metal should work well for the type of repair you need to make.


kp

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You got your own machine shop and you're asking us lot  :o. Anyway, seeing as I'm responding, may as well throw my 2 cents worth in.
TIG weld; mill dress (first option) ..................... hand dress as a last option. Bog is bog (filler to you lot), and I don't do bog.

On a serious note, those are rare cases and they deserve to be treated to the best job possible. A good mill operator would get that face done, just time setting up the job is what you'll be paying for. A good fitter (not sure what you call the trade there) would hand face that to within a small tolerance. Sandcast cases TIG weld very very well as they are near as you can get to pure alloy. I've had several cases TIG welded with 100% success. The area you are working on should also see zero warpage.
Using bog still requires that you hand finish the face in any case and at the end you have a job that may or may not last.
That's my Bog for the day.
KP
Yabba Dabba KP


markb

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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
KP, so in this quote you weren't agreeing with Chris about using "bog"?
You're right about the rarity so I'm being careful what I do here and just because I'm lucky enough to have access to a machine shop doesn't make me an expert at anything.  You guys have been around the sandcasts a lot longer than me and that's why I value your (everyones) input.  I just need to find the right machinist (is that the word you were looking for?) for the job if I decide to have it welded.
Thanks again guys.
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?)


kp

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KP, so in this quote you weren't agreeing with Chris about using "bog"?
You're right about the rarity so I'm being careful what I do here and just because I'm lucky enough to have access to a machine shop doesn't make me an expert at anything.  You guys have been around the sandcasts a lot longer than me and that's why I value your (everyones) input.  I just need to find the right machinist (is that the word you were looking for?) for the job if I decide to have it welded.
Thanks again guys.


Hmmmmm! I'm somewhat amazed that my post "Another 10 points to Chris for that info" has been interpreted as me agreeing to the use of bog. Maybe a re-read is in order. I was giving Chris the thumbs up for sharing that knowledge with us all. Fact is, I couldn't recall knowing about the info Chris shared with us so thought I'd post the compliment. All too often we suck the info up but forget to thank the source. Obviously you have interpreted my post differently. I hope others haven't.
Trades vary from country to country and here we have fitters who are not always machinists (although many are). I spose what I was saying is; if a machinist couldn't get your job set up to give you the good result you're after, then you may want to find a fitter-welder who has a special talent in hand dressing these difficult jobs (as suggested by Steve V). If bog's your lot then don't let me deter you from that path.
Mark, I've felt some animosity in your response and am a little surprised at that. I know I post in a light style and maybe tend to overwrite on occasion but, just because I don't brag and expose to the world my background and life story doesn't mean I've  done nothing, know nothing, been nowhere. If my input is grating on you then just PM me and say it and I'll withdraw from further discussion KP

Yabba Dabba KP


markb

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I probably should have started a separate thread for my case problem.  But, first off, if you felt some animosity, I apologize.  It wasn't meant to come across that way at all!!  I'm just saying I know I have a lot to learn about sandcasts and restoration and value and welcome your opinions.  If I didn't I wouldn't be asking for help.  So no, you're not grating on me and please don't withdraw from further discussion.
As far as Chris' post, in the first half he was suggesting the "instant metal" and then had the information about the coating.  I see now that the info about the coating is what you were giving him 10 points for, not the advice on the instant metal.
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?)



kp

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Shalom, peace and good will always and to all.

I think one of the biggest problems, for me at least, when participating in forums is the written form of communication and the message conveyed. Writing is a 2 dimensional and very black and white medium. We write to convey a message which has meaning but little emotion, and those receiving that message interpret that meaning and generally never an issue arises. It often happens where we read a message or comment, and struggle to understand what it is the writer is saying. A good example is the good'ol workshop manual. Without those pictures we would be lost souls. Three dimensional communication adds that bit of extra ie: facial expression, body language and sound. If I told Mr Swan to shove his peace and good will he would probably be a little pissed (and I don't want that to happen) but if I said it in his workshop with a hint of sarcasm in my voice and a smile on my dial ......... all would be well.
Mark, I'm good. Just one of those cases where a message sent has been misread and misinterpreted by me. If I had been in your workshop at the time I wrote my original post there would have been beers in hand, analysing the merits of weld vrs bog. Mr Swam would have been in church sharing peace and goodwill ;) KP
Yabba Dabba KP


markb

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I agree.  I guess sometimes those smileys help convey the right emotions.  No worries.
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?)


hondasan

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Sometimes I am sure we all "post in haste"  such that intended meaning can be missed.

As to the "never use bog", in an ideal world I agree. I wish I could weld aluminuim, or knew someone I could trust 100%! Sadly after an experience where a set of sandcast barrels was rendered scrap by a botched weld job by a guy who came VERY HIGHLY recommended some years back (and retorted that "you can't win 'em all" afterwards, and still wanted paying!), I have some reservations about commiting irreplaceable parts to others for repair (and E100 is definately in the irreplaceable category!).

I guess we all have to assess the risk and cost, take advice, and go with whatever gives us peace of mind.

Cheers - Chris R.

Chris R.
302/338


Steve Swan

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