Author Topic: Sandcast Engine #1770 rebuild - it made it!  (Read 14408 times)

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Offline newday777

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #300 on: October 27, 2023, 08:59:37 AM »
Tje later are higher I think.
Front M6 must be longer on the later breather covers if I remember correctly.

But this might be about earlier vs  even earlier, Sandcast. ;)
The M6×50  is the same all up to atleast K0- K6(just checked the fiche.
I looked at the sandcast only forum earlier and they didn't mention anything about differences between the early and later diecast.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline BenelliSEI

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #301 on: October 27, 2023, 05:04:53 PM »


Never got to the shop today but I will. I think I have a few covers to compare.
 Curious now.

Offline HondaMan

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #302 on: October 28, 2023, 05:35:54 PM »
Here 'tis, in its ready-to-run-again glory! :)
This has easily been the most-parts-replaced engine I've ever done. Between the dust-rust and the water-damaged tranny parts, I even had to create a new spreadsheet to track all the bearings (every one had to be replaced, ball, roller, and plain) and miscellaneous missing parts. I tried my hand at restoring the poor beaten-up-and-rewelded alternator cover to try to preserve the pre-"Made in Japan" logo cover, but it's not show-worthy. At the cost of new alternator covers being over $300 USD apiece now, and the co$t of all the bearings, it was just getting too expensive overall.

I have to admit that I'd forgotten all about the retainer-ringed final-drive bearings in these early ones. That was the real chase for trying to put it back together because of the unique 62mm retainer ring in the final-drive output bearing. There's only 1 left, according to CMSNL, but there's probably some other Japanese bike that still uses them, just not with Honda part numbers. (?) For a time I thought of getting a full-round 62mm ring and cutting it by half, but finally CMSNL came through.

This was the first time I ever had to make a custom chain-oiler metering bolt, too. Those poor Honda techs who had to make those from a regular bolt, one for each engine (7,818 of them!) with the 1.25" long tiny rod that skewered the oil sponge: holy cow what a tedious job that must have been! That's been removed in favor of less oiling of the rider's left shoulder and the whole left side of the bike, which these were [in]famous for as Honda struggled to make the drive chains survive the HP of these monster engines. This one's skewer-tip was already gone and someone had already filed off the broken end of it, then removed the oiling pan to try to stop the mess. The new bolt will also plug the hole in the final-drive shaft by making it with 2.0mm longer threads that cover that hole. Even my Honda mentor Jim had plugged the oiler hole in his sandcast with an early form of JB Weld and oiled his chain with his own lube he made, dubbed "Chambo's Sneaky Sh*t Chain Lube" - he also sold it at the shop! He would pull the chain off once a month, melt some of this goo in a cookie sheet pan 1" deep, lay the chain in it and let it cool overnight before reinstalling. When it cooled you could hold out 3 links of the chain straight and stiff, which helped him put it back on the bike without removing the sprocket cover: he'd lay the 2 links onto the sprocket, then put it in 2nd gear and electric-start it with the kill switch OFF to feed the chain 'round. He got about 8k miles per OEM chain, which was a record with the 16T/45T sprockets in our shop. The Diamond XD and RK Chain's clone of it changed all that, though.

Unless you look really close (and know where to look), you can't tell that all those fins were missing: Ivo did a terrific job of recreating them! :)
It's got stock-sized 61mm bores with new sleeves inside, all new crank and rod bearings that will need to be broken in like a new engine (average 0.0010" clearance), and lots of internal parts that need to be oiled up with some miles to smooth it out. I suspect it will take 50-100 miles just to 'wet' everything fully, and then its oil will have to be changed out in case I missed any grit: there was a LOT of it inside, that nasty red Houston dust.

I'm wondering what the garage will feel like when it's gone: it's been here so long and received so much attention I think I should have named it? :D
« Last Edit: October 28, 2023, 06:08:20 PM by HondaMan »
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

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Offline BenelliSEI

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #303 on: October 28, 2023, 06:19:34 PM »
Nice work, really appreciate all the details you covered. I hope mine turns out looking that good! Where did you find the top breather cover? Did you paint the cam cover?

Offline newday777

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #304 on: October 28, 2023, 06:32:33 PM »
Congrats Mark.
Well done with the sow's pink ear you got.
Do you do a test run and retorque before it goes off to the owner for install? Or was it you that heats the motors with a salamander heater to heat cycle, cool and retorque?
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline RAFster122s

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #305 on: October 28, 2023, 06:35:38 PM »
Thanks for documenting and sharing the journey with us! Congrats on it being finished up! Will you hear it run?
David- back in the desert SW!

Offline grcamna2

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #306 on: October 28, 2023, 06:47:09 PM »
Excellent  8)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
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Offline HondaMan

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Re: Sandcast Engine #1770 rebuild - I hope?
« Reply #307 on: October 28, 2023, 07:08:34 PM »
Thanks, all! Newday777, BenelliSEI, 69CB750, MRieck, you guys rock!

At my last contact with the owner, a run-test wasn't a part of the deal. I don't have his carbs, but somewhere I have a set of K0 carbs that I probably need to refurb, which could work. I don't know if I have the right intake manifold hoses: the normal ones don't fit. It would be fun to hear it run, though: at the moment I am so severely space-challenged that I'm not sure if I have the space to hook it all up for a run(?). At least, one fellow came by today to pick up his crate that has blocked the garage door for a couple of months, now, so 'twas a good day for the garage. There's 4 more 750 engines and a whole 750 & 550 out there keeping my 750 company during today's snowstorm. :D

The carb's mainjets will have to be reduced from the [probably] #120 mainjets they have now to #110 or #105 because of the K4 cam inside. The intake valve opens now at 2 degrees BTDC instead of the 7 of the K0/sandcast versions. That valve closes at 5 ABDC instead of 6-10 like the K0 versions, too. The exhaust side is similar in the later cams. They started easier and ran cleaner than the early ones, but did lose some HP above 6000 RPM for it all. This cam will also idle: the K0 didn't always do that very well.

The cam cover came in the original boxes of parts: it looks like someone did some intensive blasting (bead?) after cleaning, and then spent quite some time smoothing it out, just short of polishing it - the sprocket cover, tranny cover and clutch cover were similarly treated. The breather cover came from a K1 top end I have in the garage, which was a project someone abandoned and I ended up owning. It, and the cam chain tensioner (K7) stand out for their nicer surfaces, but they won't be seen much in the bike.
-Come to think of it, I have two 836cc abandoned cylinder sets like that, too...

I'm one to do the overnight-retorque of these heads. I think it vital to preventing leaks in the long term. On my own 750 I did that in 1980 when I went 1st oversize and it was still dry in 2006 (80k+ miles later) when I took it apart to clean up a couple rusty valves from it sitting 2001-2006, unprepped, while I healed up from cancer in those days. I guess could have been kinder to it then?  ::)
« Last Edit: October 28, 2023, 08:00:05 PM by HondaMan »
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline denward17

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #308 on: October 28, 2023, 07:21:57 PM »
Congrats Mark, it was nice to follow along on this special engine.

Offline Don R

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #309 on: October 28, 2023, 11:56:08 PM »
 Congrats on the finish, fyi in case your guy is picky, the sandcast and early cam chain tensioners had a thinner lip like some of the alternator covers.
  A mold maker once told me that the flanges and edges of cast parts will get thicker as they get newer as the dies are repaired and re-finished.
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Offline rocket johnny

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #310 on: October 29, 2023, 12:21:22 PM »
+ 1 to all of the above .  a tough project with a great ending !     great job marko !

Offline HondaMan

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #311 on: October 29, 2023, 03:28:06 PM »
Congrats on the finish, fyi in case your guy is picky, the sandcast and early cam chain tensioners had a thinner lip like some of the alternator covers.
  A mold maker once told me that the flanges and edges of cast parts will get thicker as they get newer as the dies are repaired and re-finished.

I suspect he is right: all of the surfaces on the side covers have thin edges, too. On the K0 engines I have done I have noticed both thin and thicker edges on those covers. Mostly I think they were replaced covers, though, as their surface finish didn't match the rest of the covers, nor the engine. Many of the alternator covers were replaced, probably for the usual reason, and nearly all of them lacked the 3 little copper sealing washers for the field coil's mounts, making them weep. I've always wondered how those can weep oil when the alternator barely gets any oil? The only oil that enters the alternator cover comes thru the skinny little seal behind the starter gear, which is up against the #1 main bearing, so it's just the weepage from there that makes it in.

The sealing surfaces on this alternator cover are thicker than the other covers, so I think it was a later cover. The welding over the whole "Made in Japan" logo site was deep enough that it could have filled in a logo if it was there. The damage (dent) was deep enough that the inside of the cover had to be scraped off a little to prevent the rotor hitting it. Overall, this engine's had a rough start!
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline Stev-o

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #312 on: October 31, 2023, 06:38:10 AM »
Looks great HM, thx for sharing this challenging rebuild.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline 34barab

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #313 on: October 31, 2023, 01:57:27 PM »
Thank you Hondaman for sharing your knowledge and expertise.
Current Projects: 1973 CB750K3; 1972 CB350K4; 1980 CX500D;1969 CB750.  Roadworthy: 1971 CB750K1

Offline JamesH

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #314 on: October 31, 2023, 06:28:52 PM »
A brilliant series of posts. Thanks Mark for sharing this.


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Offline HondaMan

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Re: Sandcast Engine #1770 rebuild - it made it!
« Reply #315 on: November 04, 2023, 07:03:24 PM »
Nice work, really appreciate all the details you covered. I hope mine turns out looking that good! Where did you find the top breather cover? Did you paint the cam cover?

The cam cover looks like it was hand-buffed, or something. Its finish is very smooth and the sharp edges of the details (like the "CB750 SOHC" logos) are not there like they usually are. I suspect it was in rough shape and someone spent some time cleaning it up and smoothing it out.

The breather cover is just from a K7. It looks a little out-of-place with its sharp high-pressure mold details, but that won't be very visible when the engine's in the frame. Likewise the cam chain tensioner, as the original one was missing. They are both K7 parts from a died engine I kitbashed with another to make a good K7 one day, I think for a rider in Wyoming.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com