Honda CB750 Sandcast
Beginning to End - Member Restorations => Restoration of Sandcast #1629 => Topic started by: Sam on July 09, 2014, 12:38:09 pm
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Hi everyone. Here’s the story of restoring sandcast #1629. I’m going for a high-quality job here; I plan to have an excellent running bike that looks brand new.
I’ve restored several CB750s over the last eight years or so. Here’s a picture of my last CB750 restoration; a K4 (painted like a k1):
(https://farm3.staticflickr.com/2938/14590859126_3d51afde20_b.jpg) (https://flic.kr/p/oekY5E)
I had just bought a diecast K0 to restore when I came across this bike on craigslist:
(https://farm4.staticflickr.com/3784/9667300161_202d717e58_o.jpg) (https://flic.kr/p/fJgrwZ)
(https://farm8.staticflickr.com/7321/9670531244_c63f8fb1ca_o.jpg) (https://flic.kr/p/fJy12j)
It was non-running with loads of incorrect parts. In sad shape for sure, but it was a sandcast engine with an incorrect frame (a late K0 with a lot of chopper mods). I was the first caller and the first to show up. I walked away with quite the basket case: sandcast fever had me!
Next...getting it home and tearing it apart!
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My first job was to tear the engine apart to figure out its condition. The seller had no idea what I would find since it wasn’t running.
(https://farm6.staticflickr.com/5500/9666225383_b0d450ac05_b.jpg) (https://flic.kr/p/fJaW3k)
I interpreted this as #1629, but had doubts (perhaps #1621?). The consensus thinks that it is a 9 though. (http://cb750sandcastonly.com/smf_forum/index.php?topic=1297.0)
A few pics as I took the engine apart:
(https://farm3.staticflickr.com/2809/9666219607_202eb2bb41_b.jpg) (https://flic.kr/p/fJaUjK)
(https://farm8.staticflickr.com/7338/9666218861_7a1c9a73f6_b.jpg) (https://flic.kr/p/fJaU6T)
(https://farm4.staticflickr.com/3755/9666217227_0271d0a43c_b.jpg) (https://flic.kr/p/fJaTBH)
(https://farm8.staticflickr.com/7429/9669447934_ddcb906e33_b.jpg) (https://flic.kr/p/fJsrZy)
(https://farm6.staticflickr.com/5460/9669446480_1c88a299df_b.jpg) (https://flic.kr/p/fJsryu)
(https://farm6.staticflickr.com/5510/9669442030_2d782dae1f_b.jpg) (https://flic.kr/p/fJsqeL)
(https://farm8.staticflickr.com/7386/9669436966_e3d03d0244_b.jpg) (https://flic.kr/p/fJsoJs)
Ugly! Ugly and dirty! Gotta start somewhere right? ;D
A few findings...
The good news was that the engine turned over and shift through the gears. The first bad news was that the head was from a K1 or later. The second bad news was all the brown liquid I found in the engine. At first, I was sure it was rusty water, but I quickly figured out that there was a liter or two of fuel inside the engine! Someone must have tried to add fuel through the oil tank at some point! Sheesh.
Fortunately, there was no rust on the inside and no broken parts. The next bit of bad news was that a few of the parts had been chromed (rather poorly). Some things are salvageable (the nine hole clutch cover is one of them thank goodness), other parts are not (like the alternator cover).
It looks like the chain on this bike must have puncture the engine cases at some point. Fortunately, someone did a good job of fixing the cases, so I won’t need to deal with that.
A few bits of good news...
The oil lines appear correct:
(https://farm8.staticflickr.com/7369/9666223067_2fe883fbd9_b.jpg) (https://flic.kr/p/fJaVmp)
Lots of original bolts:
(https://farm6.staticflickr.com/5500/9666224393_ed4c38caa7_b.jpg) (https://flic.kr/p/fJaVKg)
The oil pump screen appears to have done its job (no tears):
(https://farm4.staticflickr.com/3685/9666212243_4e25dac242_b.jpg) (https://flic.kr/p/fJaS8M)
Next...the search for a correct frame.
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Great job! Patience, persistence are virtues which lead to rich reward.
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As I mentioned, the bike came with a much later K0 frame (29xxx). Finding a correct frame (within 300 of the engine number I am told) took almost nine months. After about five months, I found a sand cast frame in Texas #2685. Not technically correct, but it was the first sand cast frame I came across. I bought it thinking it was my only chance. The seller did a great job packing it:
(https://farm8.staticflickr.com/7392/11315545586_1e5afeec8f_b.jpg) (https://flic.kr/p/ieV8ty)
The frame was in great condition, so I set it aside as I searched for more parts.
About four months after that, frame #1387 appeared on ebay. I won it and had a correct frame! Of course, it wasn’t that simple. The passenger peg drops on the frame had been damaged. They were still there, but a portion of the tubing was was crunched; they needed to be replaced. I was able to scavenge the correct tubing from the K0 frame that the engine came with. Tack welded into place:
(https://farm6.staticflickr.com/5192/14123234967_9a6f0b451f_b.jpg) (https://flic.kr/p/nw2gHa)
The trick was to make sure that the exhaust lined up perfectly when the engine was mounted (with gaskets installed):
(https://farm4.staticflickr.com/3771/14329951503_fe00351604_b.jpg) (https://flic.kr/p/nQhKkn)
By the way, did you know that the eyelets that connect to the exhausts and passenger foot pegs are welded to the tubing in different ways? Take a look...
Frame #2685 (same on the #1387):
(https://farm4.staticflickr.com/3900/14427904427_77c89ab8bb_z.jpg) (https://flic.kr/p/nYWMjT)
K0 frame (#29xxx):
(https://farm4.staticflickr.com/3865/14427646000_300a46708e_z.jpg) (https://flic.kr/p/nYVsvf)
See how the horizontal tubing on the K0 is welded to the eyelet while the sandcast frame horizontal tubing is welded above the eyelet? Who knew?! Well, I didn't ;D
Anyway, the newly welded frame fits up perfectly. I also did a quick fix on the side stand mount. Now its ready to be blasted and painted. I'll come back to that later.
Next...the engine cases!
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At some point the engine was painted black with very poor quality paint. That combined with decades of caked on oil and grime led to some very nasty cases. Worse, a small bit of the case just above the top left mount point was broken off. You can see it just above cylinder #2 in the this pic:
(https://farm4.staticflickr.com/3813/9666210447_73c070d995_b.jpg) (https://flic.kr/p/fJaRAP)
I had an expert welder friend of mine solve the broken tab problem. He did a great job. I then brought the cases to a mechanic friend who has a high-temp cleaner. I then bead blasted the cases and prepped them for paint:
(https://farm3.staticflickr.com/2934/14591685762_6e8e6dd904_b.jpg) (https://flic.kr/p/oeqcP1)
My top-of-the-line engine paint booth (the idea came from UKPete (http://cb750sandcastonly.com/smf_forum/index.php?topic=1280.15)):
(https://farm3.staticflickr.com/2907/14405771598_d83931710f_b.jpg) (https://flic.kr/p/nWZm1o)
Painting complete (I used Duplicolor High Heat Engine Paint called Aluminum Cast Coat 1650):
(https://farm4.staticflickr.com/3859/14612447233_2381bf9127_b.jpg) (https://flic.kr/p/ogfBtp)
Then off to the oven for curing. I cooked them at 225F for about 30 minutes. Came out very nice with excellent adhesion (note the fixed area above the left mount point):
(https://farm6.staticflickr.com/5548/14591692422_8e5c5a3b65_b.jpg) (https://flic.kr/p/oeqeMQ)
Thats where I am as of today.
Next...building the engine!
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Nice progress! Do you still have that other sandcast frame?
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Hey Greggo!
Yeah, frame #2658 is hanging in my garage. For sale if anyone needs a frame. Its in great shape.
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Second dibs on the 2658 frame if Greggo passes.
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Hi ujeni looks great what your doing, I was pleased to see the engine spray stand, glad you liked my idea great news you picked up a frame, given how hard it is to find, keep up the good work fella
Pete
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Hey Pete!
You need to post more pics so I can copy more of your ideas! Ha!
On the frame, I'll send messages in order of interest expressed and post when it is sold.
I'm on vacation right now, but I'll be assembling the engine when I get home next week! Prepare for questions :)
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Back from a quick vacation and I have a few days lined up for the sandcast.
Last night I coated the insides of the engine cases:
(https://farm6.staticflickr.com/5595/14490135658_8a87f36488_b.jpg) (https://flic.kr/p/o5rJv9)
(https://farm4.staticflickr.com/3863/14490093400_4b74aa8d98_b.jpg) (https://flic.kr/p/o5rvWy)
Next....transmission!
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Sam, Did you get my PM? Keith
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Sam, Did you get my PM? Keith
Yup. Sorry for the delay. I've replied!
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Got a good bit done over the last week. It helps to be home on paternity leave!
I started by replating the original "8" bolts. Original of the left, beed blasted in the middle and zinc plated on the right (needs a bit more polishing in this example):
(https://farm3.staticflickr.com/2932/14718562006_86e550c3c3_b.jpg) (https://flic.kr/p/oqCtGs)
The bottom end of the engine went together fairly easily. I must admit that it did take some time to figure out which crank shaft bearings to use (thanks for the help out there...you know who you are!):
(https://farm4.staticflickr.com/3857/14555113947_448c91dcf3_b.jpg) (https://flic.kr/p/obbLht)
I then flipped the engine over...
(https://farm4.staticflickr.com/3915/14738397731_1cef146d18_b.jpg) (https://flic.kr/p/oso9aH)
...rebuilt the oil pump (note at the top that someone must have tried to file a bit of the oil pump down at some point...no idea why and it doesn't affect the operation of the pump)...
(https://farm4.staticflickr.com/3864/14741270132_6478ee6215_b.jpg) (https://flic.kr/p/osCS2S)
...and sealed up the bottom end (after priming the pump of course):
(https://farm3.staticflickr.com/2899/14555112427_87ae4e9b4c_b.jpg) (https://flic.kr/p/obbKQg)
Next was the top end....
(https://farm6.staticflickr.com/5557/14753669995_f2d56c0c1c_b.jpg) (https://flic.kr/p/otJq5B)
Hmmm...which is the new one? ;D
(https://farm6.staticflickr.com/5572/14566985980_221999a36b_b.jpg) (https://flic.kr/p/oceBqG)
Got the top end assembled:
(https://farm3.staticflickr.com/2902/14576921038_15b6665127_b.jpg) (https://flic.kr/p/od7wLN)
Next...the clutch!
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Sam, amazed at your quality and progress
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Thanks! I am happy so far except with the zinc plating. It is strong, but I need to practice my polishing! ;D
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Nice work sam, you seem to be steaming ahead with the build, keep up the good work
pete
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On to the clutch...
New springs, steel plates and friction plates:
(https://farm6.staticflickr.com/5585/14666399599_f91ff9a068_b.jpg) (https://flic.kr/p/om28CB)
All done!
(https://farm4.staticflickr.com/3887/14852685102_1aef48d84c_b.jpg) (https://flic.kr/p/oCtTPC)
That didn't take long!
Next...priming the tank and frame!
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Just out of interest why did you paint the inside if the engine, had the factory coating been removed?
pete
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The factory coating was long gone. Especially after beed blasting it!
I spoke with a sandcast expert who coats the insides of all of his engines with Glyptal. It seals the inside of the engine (sandcast engines are known to have pores from what I am told) and it quickens the flow of oil through the engine. I did my own research and found that it is a very highly respected product that a lot of restorers use. After applying it to #1629, I can see why; I'll use it on every engine I build from now on!
Honda used their own engine sealer back in the day of course, so I don't consider it incorrect for this engine to be sealed.
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As I mentioned earlier, I had to track down a correct frame and do some welding to get it looking great again. After having it blasted I needed to get it primed as quickly as possible (I live next to the ocean which is murder on bare metal!). I use an epoxy primer to fully seal the frame properly. I'll be wet-sanding the epoxy primer down before the next coat, so I was able to apply this coat in my driveway (not so for any coats after this!). The epoxy primer went on really well. Strong stuff!
(https://farm6.staticflickr.com/5557/14863037652_6ec7a67f92_b.jpg) (https://flic.kr/p/oDoXgS)
I found a wrinkle tank that had been repainted (poorly) and had a bit of surface rust on the inside. The good news was that it had no leaks or dents and was pretty cheap! I blasted the tank and found that the emblem brackets were gone. Wasn't too hard to fabricate new ones. The rust on the inside of the tank was trickier. I have coated the inside of tanks before, but I have never been fully satisfied with the results. Knowing the importance of getting this tank right, I brought it to a radiator shop. The used their acid tanks and a specific tank liner that I really like (made by POR15) and it came out beautiful! Unlike other tank liners out there, POR15's liner is silver; looks like new!
(https://farm6.staticflickr.com/5570/14884138413_791eebdaa1_z.jpg) (https://flic.kr/p/oFg6N6)
(ignore the brown shadow in that image above...its not rust, just the result of using the flash in a dark garage!)
I then epoxy primed the tank. Turned out great! Here they are together:
(https://farm6.staticflickr.com/5562/14676746869_9ca16919e9_b.jpg) (https://flic.kr/p/omWavP)
Like the frame, the tank will be wet sanded before painting any more coats.
I'll come back to these and several other parts that need paint, but for now I can sleep better knowing they won't rust!
Next...priming the plastic parts!
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Great progress sam, does the epoxy primer sand down easy, i see your ladder is making itself useful again, it is holiday season for me i have been spending alot of time in my motorhome so have not had the chance to do any work on my bikes, but watching your progress gives me the urge to get on with my frame, and engine
pete
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Yeah, the epoxy primer sands down just like any other paint. I've used it on many restorations. For example, I restored a 1988 Honda Africa Twin and epoxied the tank while I used normal primer elsewhere:
(https://farm4.staticflickr.com/3679/9670593086_a7ff9e5c9a_b.jpg) (https://flic.kr/p/fJyjpy)
Then paint and clear:
(https://farm6.staticflickr.com/5511/11801904844_92e8c4b203_b.jpg) (https://flic.kr/p/iYTR91)
Great stuff!
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A quick update. I've painted the frame and many of the other black parts. I worked with my paint mixer and created a custom formula to emulate the "semi-gloss" that the frame and many parts originally had. A slightly blurry pic after I painted the frame in my garage:
(https://farm6.staticflickr.com/5605/14981107303_44cdf05979_b.jpg) (https://flic.kr/p/oPQ6gv)
Next, I (finally) finished polishing the engine parts and got the last bit of the engine completed. I'll likely do a tad bit of touchup on the clear coat at some point, but it is looking pretty good now:
(https://farm6.staticflickr.com/5609/15437815677_46988242c7_b.jpg) (https://flic.kr/p/pwbQKP)
Up next: putting the engine in the frame and "yellow-passivating" the spoke nipples!
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Sam that looks fantastic fella, the engine could go on a stand and sit in your living room to be admired ha ha
I am working on my frame at the moment, i have just welded a side stand bracket on, and will be shot blasting it soon ,my mate has given me some chassis black paint which looks quite similar to the paint i found under the silver sticker on the head stock so i will give that a go
pete
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The engine is in the frame! Went far smoother than in previous builds. For inspiration, I did it the same way that it was done in 1969:
(https://farm6.staticflickr.com/5609/15448672248_0d35d991b9_o.jpg) (https://flic.kr/p/px9u35)
Here's the sequence:
1. Set up some books under a few Mexican blankets:
(https://farm4.staticflickr.com/3941/15632133201_9736f32eb4_b.jpg) (https://flic.kr/p/pPmLzX)
2. Set up the engine on its side:
(https://farm4.staticflickr.com/3934/15634808295_c58a781bb9_b.jpg) (https://flic.kr/p/pPAtNg)
3. Prep the frame with water pipe insulation to avoid scratches:
(https://farm6.staticflickr.com/5614/15014627903_441451bbef_b.jpg) (https://flic.kr/p/oSMTLT)
4. Carefully lower the frame onto the engine, secure it, tip it back up and admire:
(https://farm4.staticflickr.com/3954/15448686458_f3f44d609a_b.jpg) (https://flic.kr/p/px9yg5)
Ok, maybe that's not exactly how they did it back in 1969 ;D
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Bravo !
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Beautiful work.
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Lots of progress! First off, the wheels. Polished and sealed the hubs and then had the rims rechromed:
(https://farm4.staticflickr.com/3878/15159430171_b628c313ab_b.jpg) (https://flic.kr/p/p6A3rH)
Then figured out how to add the yellow passivate to the zinc spoke nipples. Here's a before and after:
(https://farm6.staticflickr.com/5610/15054505963_affa345522_b.jpg) (https://flic.kr/p/oWjh8D)
Wheel truing:
(https://farm6.staticflickr.com/5604/15406169510_930444c4d8_b.jpg) (https://flic.kr/p/ptoDsf)
Decided to go with the dunlop set of tires from Yamiya. Not cheap, but they are the most accurate I could fine. Look nice:
(https://farm8.staticflickr.com/7482/15854983565_d19a4d4288_b.jpg) (https://flic.kr/p/qa3WeB)
Next up, paint!!
Paint is the toughest part; so many steps that can go wrong and ruin everything! I've painted several bikes now, so I thought, why not a sandcast?! ;D
After many hours of prep work and priming (prep really is 80% of it), I was in the paint booth putting the metallic basecoat on:
(https://farm8.staticflickr.com/7574/15642146727_49095a1b81_b.jpg) (https://flic.kr/p/pQf6fX)
When I bought this bike it was in horrible shape (see the beginning of this thread). The original airbox was broken and had terrible black paint on it...but I was able to see candy ruby red beneath the black paint. I figured it should remain the same color ;D
It is impossible to get the right color in a photo...especially under artificial light, but here are a few pics:
(https://farm6.staticflickr.com/5606/15826853791_da9bac6e66_b.jpg) (https://flic.kr/p/q7yLev)
(https://farm9.staticflickr.com/8677/15825429921_7947192b41_b.jpg) (https://flic.kr/p/q7rsY2)
(https://farm6.staticflickr.com/5613/15805094696_61a3165c95_b.jpg) (https://flic.kr/p/q5Df1G)
I'm very happy with the paint! Gotta love that candy finish huh?!
Finally, I took a rainy day to finish the gauges:
(https://farm8.staticflickr.com/7496/15235325043_477c6f3059_b.jpg) (https://flic.kr/p/pdi2kZ)
The gauge faces and jewels are original. Unfortunately, the flasher jewel appears to have lost its orange coloring. Should I replace it? Also, I found instructions on this forum to reset the odometer. I've never done it, should I try?
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I have huge respect for people who undertake as much of the work themselves , candy paint can be very tricky but it seems like you have cracked it ujeni , the wheels look amazing, did you dip the zinc nipples in gold passivate for 20 seconds? to get that colour
I would definitely replace that jewel if i were you, every thing else you have done is perfect the jewel will always bug you if you dont do it now
pete
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Looks to me you've done a nice job with the paint and you should be well pleased. I would stick with original for the instruments as they look to be in great condition. A buggar about the flasher jewel but a reproduction would be acceptable unless someone can give you an original. KP
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Excellent progress. Very nice work! I wish my project was moving along as well. ;)
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A compliment from you guy's is flattering...this is my first sandcast, so I am always looking for advice. Don't hold back! ;D
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I have huge respect for people who undertake as much of the work themselves , candy paint can be very tricky but it seems like you have cracked it ujeni , the wheels look amazing, did you dip the zinc nipples in gold passivate for 20 seconds? to get that colour
I would definitely replace that jewel if i were you, every thing else you have done is perfect the jewel will always bug you if you dont do it now
pete
Thanks Pete!
The Yellow Passivate takes about 1 minute to get the right shade (depending on how much you have diluted it of course). I then clean it with water and let it dry for 24 hours. Im impressed with how well it is holding up!
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There's something exciting about achieving "roller" status! Still lots to do, but I am starting to see this thing come together!
(https://farm8.staticflickr.com/7578/15871129981_b99cbb9d22_b.jpg) (https://flic.kr/p/qbtG16)
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Beautiful work. Purely lovely. And a great thread.
Having been out of the loop for so long, i'm not very aware of parts sources. How much or what sort of parts are you able to source from Honda ?
The reason i am asking, i am preparing to start a restoration for a gentleman's Sulphur Yellow 1976 CB750F Super Sport. I know of Western Hills Honda, CMC, DSS, and of course Yamiya. But Yamiya is pretty much K bike focused. My concern, the 75-76 F models, being a somewhat limited production, aren't alot of parts out there unique to the model. Hopefully not as difficult as i hope it won't be... seat trim, switch/lock assembly, tank badges, other odds and ends.
So, that's why i'd appreciate if you can share with me where i might go looking for F parts.
Please accept my apology for deviating from your thread.
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Thanks.
Parts are coming from yamiya, eBay, cmsnl and hondabikes.com. My guess is that you will find a lot of parts for your super sport on hondabikes.com. They have the best prices I've found.
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Next up was the seat...I was able to restore the original seat pan. Everything else (foam, cover and hardware) came from Yamiya. Nice stuff ;D
Getting ready to stretch the cover:
(https://farm9.staticflickr.com/8659/16016231945_f8d71db02a_b.jpg) (https://flic.kr/p/qpinL6)
Done! Underside:
(https://farm9.staticflickr.com/8596/15773783097_75a54cf69c_b.jpg) (https://flic.kr/p/q2SLax)
Top:
(https://farm8.staticflickr.com/7547/15958854802_a83150a1ae_b.jpg) (https://flic.kr/p/qjeix1)
I'm happy with how it turned out. Yamiya's stuff is top-notch! Matches my two original seats!
Lots of other stuff has been taking shape like the wiring harness, rear brake, front brake (had the disk ground down by my machinist...looks amazing!), oil tank, cables and more. A few pics:
(https://farm9.staticflickr.com/8683/15828648408_52ee5923c6_c.jpg) (https://flic.kr/p/q7HXHb)
(https://farm8.staticflickr.com/7519/15393795934_f8ef836f1f_c.jpg) (https://flic.kr/p/psiedJ)
(https://farm8.staticflickr.com/7577/15990342496_e0f1a92116_b.jpg) (https://flic.kr/p/qn1FJh)
I know what you are thinking...I need to clean up my garage! Ha!
I've started in on the carbs. Will be zincing a lot of parts. So many parts in fact, that I have ordered a new plating kit that should do a better job. Once the carbs are done, I will only have a few things here and there to finish. Getting exciting!
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Looks amazing!
At the rate you are progressing it won't be long before you complete the bike.
You will hear the sweet sound of four cylinders roaring soon, so keep posting the great pics.
DW
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Looks beautiful!!! And BTW, your garage looks a lot like mine! :)
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Its been a little while since I posted, but the good news is that the bike is done. Its been an adventure!
To make a long story short, I had to rebuild the kickstart and repaint the bike.
The first problem was caused by a weak recoil spring, a slightly bent kickstart shaft and (here's the odd one) a non-OEM oil pump gasket. The Yamiya oil pump gasket was thicker than the correct OEM gasket which caused the oil pump to press harder against the kickstart wheel. With a fresh spring and fresh re-zinced kickstart shaft and the correct OEM oil pump gasket, it was all fixed.
Next was the paint. I bought my paint kit from hondamotorcyclepaint.com. They make kits for many honda colors and I figured their Candy Ruby Red would be correct. Looks nice, but was it correct? NOPE!! Two problems: the red was the wrong shade and the metallic basecoat flake was far too corse. I didn't realize this until I bought an original Candy Ruby Red tank with near-perfect paint. Once I knew what I was going for, my local paint dealer and I identified a match for the metallic coat and a match for the candy. I repainted everything and got a really great result. I'm pleased!
Here's the final product:
(https://farm9.staticflickr.com/8773/17314925659_8f9e9dc730_b.jpg) (https://flic.kr/p/so4wa2)
(https://farm8.staticflickr.com/7673/17501230995_a566cb50a7_b.jpg) (https://flic.kr/p/sEwoeZ)
I'll be showing this bike and sandcast #410 at the Quail Motorcycle Gathering (http://signatureevents.peninsula.com/en/Motorcycle/Motorcycle.html).
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Building and showing this bike has been fun. I just found a second three-digit bike, so this bike is now on eBay:
1969 Honda CB750 K0 Sandcast Fully Restored (http://www.ebay.com/itm/Honda-CB-/131541300145)
Man it is a pretty one! I'll miss it!