Honda CB750 Sandcast

General Category => Member's Bikes => Topic started by: Chip on July 15, 2022, 07:27:37 pm

Title: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 07:27:37 pm
Hi all! Thought I’d make a post and introduce myself! I own a couple sandcasts fully restored later one and I recently picked up #173 that had been left to languish since about 1991! After much work she’s a runner and will probably stay a patina queen for the foreseeable future while I enjoy it on the back roads of Vermont! Gotta say this is a fantastic site!
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 07:30:04 pm
Few photos!
As found, and out for a cruise enjoying the scenery!
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 07:34:44 pm
Sorry the pics are sideways not sure how to fix that...
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 08:06:57 pm
Here’s a few photos of the carbs before and after!  Tank cleaned up well too!
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 08:08:57 pm
Couple more!
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 15, 2022, 08:10:33 pm
And the other one that doesn’t get out much!
Title: Re: Sandcast #173 back alive!
Post by: kp on July 16, 2022, 03:21:36 am
Man what a great machine I just love it. Whatever you do, don't sell, remove or trash anything from that low number gem. Unique parts will include the 19l tank, rear hub, swing arm, instruments, mirrors, switches, engine parts and on and on Very unique parts to these low numbered machines. Enjoy it while you have her  :)
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 16, 2022, 06:43:24 am
Hi KP! Don’t worry everything I’ve removed including the rusty front brake line has been saved in a box! I realize these early machines are quite different, it’s neat to put my later one, which was almost near the end of production next to this one and look for subtle differences!
Title: Re: Sandcast #173 back alive!
Post by: acruz on July 17, 2022, 12:14:43 am
Nice survivor Chip! I always love to see these early cb750’s back on the road! When you get a chance  could you please post more pictures of your early bike. Like Kp said, you will have some of the rarest parts on your bike due to its early vin.  Also what is the number on your other Sandcast?  Congrats and welcome.
Title: Re: Sandcast #173 back alive!
Post by: Wayne on July 17, 2022, 08:50:03 am
Welcome to the site Chip. I rotated your images for you. Unfortunately I can’t modify them within your posts.
Title: Re: Sandcast #173 back alive!
Post by: hondasan on July 17, 2022, 10:34:50 am
Hi Chip
Very nice survivor - ride and enjoy!
Any chance you would share the engine number?

Chris R.
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 18, 2022, 07:27:46 am
I posted it to the registry I believe, frame #173 and engine is #501

Thanks Wayne for rotating my pictures! And happy to post more photos of anything people might be curious of!

I’ve put about 75 miles on it now, big thing to do I think is I need to repair the pipes on cylinders #3&4 as they are rotted out right before muffler in typical spot, I thought of buying some repops from yamiya but I’d have to leave them out in the rain for a few months to match the patina of this thing so I think I’ll just weld in some metal and try to make it look as original as possible until I can find a couple used/worn looking no number pipes which with the scarcity might be never lol
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 18, 2022, 07:46:10 am
Nice survivor Chip! I always love to see these early cb750’s back on the road! When you get a chance  could you please post more pictures of your early bike. Like Kp said, you will have some of the rarest parts on your bike due to its early vin.  Also what is the number on your other Sandcast?  Congrats and welcome.

Thanks! And other bike is frame #6494 and engine #6997
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 25, 2022, 07:45:22 pm
Enjoyed a little time outside in the fresh air today fixing a few things on the bike, in an effort to keep it as original as possible I patched the pipes, not my best work but much quieter and will do what I need. May at a later date buy a set of the yamiya pipes but I feel better knowing these were the original pipes on the bike even if they’re not the nicest they match the patina pretty well. I also got caught in a pop up sprinkle while wrenching away, and when I was done started the bike and turned on the fuel and got a zap from touching the petcock, I thought I was hallucinating or something, and I touched it again and got another zappppp! I believe the coil may have gotten wet when I had tank off to weld and maybe touched the tank slightly with it back on. No problem when I bought the bike it came with two NOS Honda coils so I swapped those on and no more tingly fingers when turning fuel on or off with bike running.
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 25, 2022, 07:55:04 pm
Few more pics! I figured I’d keep this thread updated with what I do to the bike, if it should be moved to a different section of the forum by a moderator that’s totally fine!
Title: Re: Sandcast #173 back alive!
Post by: kp on July 26, 2022, 04:37:57 pm
Notice anything different with your oil tank decal  ;)
Title: Re: Sandcast #173 back alive!
Post by: Chip on July 27, 2022, 07:10:28 am
Notice anything different with your oil tank decal  ;)

I did! That’s pretty neat!  ;)
Title: Re: Sandcast #173 back alive!
Post by: vnz00 on August 14, 2022, 06:20:56 pm
Hi Chip, good work getting her running again.
I was watching this one with interest when it came up for sale.  If you check the registry, one of my pals has 540/173 which is a similarly, if reversed, situation to your VIN and Eng no's.
Just wondering if your bike came with the horizontal vent carbs (I did note the long choke arm)?
Also, would you mind sharing the numbers stamped near the drive sprocket on each half of the engine case please?
Its a good example how Honda didnt strictly stick to the VIN / Engine gap that seems to be common lore amongst many people now.
Thanks.
Title: Re: Sandcast #173 back alive!
Post by: Chip on August 18, 2022, 04:38:35 pm
Hi VNZ00! I’ll try to get some more info/photos this weekend! Happy to help!
-Chip
Title: Re: Sandcast #173 back alive!
Post by: Chip on August 27, 2022, 09:41:03 am
So it would appear it does have the horizontal vent carbs, and the numbers stamped on case halves by sprocket say 975 on both sides, what does that mean?
Title: Re: Sandcast #173 back alive!
Post by: Chip on August 27, 2022, 09:42:47 am
Also has this really cool vacuum gauge to vacuum synch the carbs which works real nice, put new vacuum lines on it and away we went!
Title: Re: Sandcast #173 back alive!
Post by: Wayne on August 27, 2022, 02:40:51 pm
Also has this really cool vacuum gauge to vacuum synch the carbs which works real nice, put new vacuum lines on it and away we went!

Bowman gauge. Nice!
Title: Re: Sandcast #173 back alive!
Post by: acruz on August 30, 2022, 09:53:35 am
How does that gauge work?  Does this allow you to sync the carbs?
Title: Re: Sandcast #173 back alive!
Post by: Chip on August 30, 2022, 10:16:23 am
Yes, nice and easy on the fly carb synching! Works great!
Title: Re: Sandcast #173 back alive!
Post by: vnz00 on August 30, 2022, 06:12:21 pm
So it would appear it does have the horizontal vent carbs, and the numbers stamped on case halves by sprocket say 975 on both sides, what does that mean?

Hi Chip, sorry for the delayed reply.  Ive been curious about the numbers (sequence numbers) you posted a pic of for a while and thought of them as a better indicator of when the engines were assembled.  For reference, my friends engine #173 has a sequence number in the 8xx range (VIN #540).  Another engine #17x I have pics of has a sequence number in the 2xx range.  So the engines were likely produced, tested and later assigned an engine number.  Eng #173 was likely produced around the same time as your engine, but assigned an earlier engine number, one from an engine which perhaps didnt pass inspection.  VIN 540/173 was built with engine and frame parts in the VIN 5xx range though (no horizontal vent carbs).  Your engine however is a later engine number, but given the horizontal vent carbs were only used on the first few hundred bikes, It may be that the engine originally assigned to your frame at the factory didnt pass inspection and Honda transferred the earlier parts to a later engine and then installed that into your early frame.

It would be interesting to know also if your engine has the early waffle cover too, which might suggest that Honda transferred all the parts from an earlier engine to your cases.

In any case, no reason to doubt the pairing.  There's been quite a few instances of larger VIN/Engine number gaps on early bikes and when you take into consideration the sequence number rather than the actual engine number, it brings a little more clarity.  Thanks for replying.
Title: Re: Sandcast #173 back alive!
Post by: Chip on August 30, 2022, 07:23:41 pm
Very interesting! Thanks for elaborating that makes a lot of sense. I could pull the valve cover and see if it has the waffle pattern this winter and report back, can the cover be pulled with engine in bike? I have no reason to remove the engine as it’s running great currently, no leaks even amazingly!  (Quickly knocks on wood)
Title: Re: Sandcast #173 back alive!
Post by: vnz00 on August 30, 2022, 08:37:39 pm
Hi Chip, I think it might be easier to look through an inspection cap or two with a good torch, rather than remove the rocker cover in frame.  I think it is possible but best avoided in your case so you can keep it sealed up!
Title: Re: Sandcast #173 back alive!
Post by: hondasan on August 31, 2022, 11:51:39 am
Hi Steven
Many years ago I had #1256 / E665 which was known to be factory correct / original. It had horizontal vent carbs on it. Factory assembly pictures show the engines to have the carbs attached BEFORE being fitted into the frame, so engine number rather than frame number may be a better indicator as to which carb types are correct. That said, early engines held back  for re-work and so fitted in later frames may of course end up with later carb types fitted?
Just my observations / speculation.

Chris R.