Author Topic: 1970 CB750 K0 restoration - going for original (Read 41765 times)

Johnie · « **Reply #50 on:** March 28, 2010, 02:44:41 PM »

Quote from: egar on March 28, 2010, 02:36:12 PM

Thanks, JOhnie. Any thoughts about my valve head cover situation? Should I just buy a replacement on Ebay and are other years interchangeable?

Here is my take on your cover...if it was me I would replace it. Figure if you make a fix and it lets loose, you have to remove that motor again to replace it. For the cheap cost to replace it I would replace it. Plus, I bet a fix would "look" like a fix. With all you are doing to that bike you want it to look good too. Per my parts book the 69-74 are the same cover. I bet the 75-76 are also, but my parts book only goes to 74. They list it as part number 12310-300-040 superseded to 12310-300-050. Hope this helps...

egar · « **Reply #51 on:** March 28, 2010, 03:51:55 PM »

You are right. After I asked you the question, I looked on ebay and found an OK one that supposedly is not damaged (but will need serious polishing) from a 72. The total was about 34 bucks including shipping. I know that divot would have bothered me.

dhall57 · « **Reply #52 on:** March 28, 2010, 05:05:19 PM »

70 KO for $500 Great find for you!! Here's some pics. of a 70 KO I ran across at a estate auction sale last Nov. Bike had been parked in a garage for the past 20 years, but still all original and only 5000 miles. When I left the sale bidding had got up to $1995 on the bike, but I don't know what the final high bid was. Somebody got a nice restore project. To bad I didn't have any money to bid with at the time. But since than I've purchased a 76 CB750 that I really like.Here's a pic of it also.

egar · « **Reply #53 on:** March 28, 2010, 06:57:22 PM »

Dhall,
That bike is in much better shape than mine was. I would have paid 2k in a heartbeat. With the powdercoating, the engine gaskets I ordered today and a replacement valve cover, I'm already at $1k including the cost of the bike itself...

mcpuffett · « **Reply #54 on:** March 29, 2010, 02:08:14 PM »

Hi i am watching your rebuild with great interest , looking at the pictures of your engine with the cam cover off you have alot of rusty parts in there that will need a lot of cleaning to stop your oil ways getting blocked, you may be as well to remove the head and remove all the parts and clean them well, replace the valve stem seals and the pucks under the cam towers and i would also recomend you take of the sump and check in there to, that way you can clean the oil screen and have a look at the bottom end to see if it is rusty or not, cheers Mick.

traveler · « **Reply #55 on:** March 29, 2010, 09:06:16 PM »

There is no way I could have left that K0 barn find.....lustworthy!

~Joe

egar · « **Reply #56 on:** March 30, 2010, 10:20:37 AM »

Thanks, Mick. I have downloaded the shop manual from this site and am nervous about going this deep into the engine, but I figure that if I take my time and ask a lot of questions from you 750 experts, I should be OK. Once I get past the engine/carb portion of the restoration, the remainder will be a piece of cake.

egar · « **Reply #57 on:** April 04, 2010, 12:59:29 PM »

OKay experts,

I have the valve cover off and am following the shop manual. I tried to spin the cam wheel to line up the marks on the end of the shaft for removal but the cam won't move. The engine is in neutral. Shouldn't it turn? The motor wasn't frozen when I removed it.
Am I doing something wrong? Gaskets are in the mail and on the way here....

egar · « **Reply #58 on:** April 10, 2010, 08:58:03 AM »

Finally got the head off. The four heat bolts weren't even that tight, which is good since I could only fit a philips head screwdriver down the outer holes. What do you guys do if that doesn't work? The openings on those two outers weren't large enough in diameter for a socket.
I'm thinking of using brake cleaner to get rid of all the carbon buildup. Is there a better way?

What happened to photobucket. It won't let me copy and paste phots the way I used to?

http://s485.photobucket.com/albums/rr218/egar_photo/?action=view&current=GEDC0258.jpg&newest=1

http://s485.photobucket.com/albums/rr218/egar_photo/?action=view&current=GEDC0258.jpg&newest=1

http://s485.photobucket.com/albums/rr218/egar_photo/?action=view&current=GEDC0255.jpg&newest=1

Zaipai · « **Reply #59 on:** April 10, 2010, 10:45:25 AM »

Photobucket is odd some times..
If you right click and select view image and them paste and highlight the link then add the image tags like below it should work (with the brackets)...

like this
img width=600 height=400]http://i485.photobucket.com/albums/rr218/egar_photo/GEDC0258.jpg[/img

.: Scott :.

egar · « **Reply #60 on:** April 10, 2010, 02:49:13 PM »

Thanks for the tip. I never usually have a problem, but I did today.

dhall57 · « **Reply #61 on:** April 11, 2010, 04:26:57 AM »

egar, been keeping up with your KO project. Your doing great and the powdercoating on frame looks awesome!!! Makes me wish I had begged,borrowed or stole some money last year at that auction sale when I let this KO get away from me. Well if I knew then what I know now I would have that KO in my garage. But I must admit I'm happy with my 750 K6.

dhall57 · « **Reply #62 on:** April 11, 2010, 04:31:32 AM »

the chev.truck behind the KO sold for $16000.00 !!!!

Brown Bomber · « **Reply #63 on:** April 11, 2010, 05:33:14 AM »

Quote from: egar on March 27, 2010, 01:06:55 PM

Question:
Also, anyone have a recommendation from my last question about locating tapered bearings? Dennis Kirk says they don't have them to fit my year...

I'm surprised Dennis Kirk didn't have tapered bearings to fit the K0, the original bearing part numbers are the same as whats in my K2. The All Balls set that I bought was originally for an '85 Nighthawk 450, but I traded the bike for a '76 CB500T, before I got around to installing them. After checking the part numbers I discovered the All Balls fit the 500T as well, again never got them installed, then comes along my '72 CB750K2. The stem bearings on it were really bad., Low and behold the All Balls kit that fits an '85 Nighthawk 450 shares the same part number as the one for my '72 750. All Balls part number 22-1011 is finally installed in my 750, and working great. (must have been fate)

egar · « **Reply #64 on:** April 11, 2010, 05:46:21 AM »

Dhall,

It hurt to shell out 370 for the powdercoating, but after spending a whole day with a buddy sandblasting my last frame for the 550 and then using some primer he had (which was some kind of horrible industrial concoction used on bridges) and then painting layer after layer of eastwood chassis paint and then after all of that time seeing it chip to reveal the white primer, it was amazing to drop off all of my black bits on one day and picking them up the next day with such a shine that they still look wet. In fact they are probably too glossy for the purist, but I think the bike will look ok.
That chevy truck, by the way, looks like a 65 or 66. I had one many moons ago.

Bomber,
I know I'm going to have to figure something out about tapered bearings and I wonder if some of those that I've seen listed to fit a 1970 k1 would also fit the 1970k...
I plan on spending today picking up tools and cleaner items and continuing work on the motor. this is definitely the tedious part for me.

egar · « **Reply #65 on:** April 11, 2010, 04:19:22 PM »

Spent the day getting the cylinder head off and doing a lot of scrubbing and cleaning. Bought a valve compressor at the auto supply place but it didn't work so I returned it. I also picked up brake cleaner, engine cleaner, scotch bright pads, wire brushes that I saw on sale - sort of like metal toothbrushes - blue shop towels, rags, etc. etc.
A neighbor stopped by and has been curious about my projects. He also happens to be a motorhead - cars and boats - but is willing to help me with the vavles and cylinders. This is a major event for me. He knows how to hone cylinders and clean up tappets and such.
I have much more cleaning to do but I'm starting to feel like at least near the bend if not around it regarding the engine. Sore back, so I'm going to kick back and check out all of your projects...

Just out of curiosity: I noticed that some of the piston rings are flush withe piston and very tight, while others are bouncy and squeezable. Of course, there are measurement that I must follow in the shop manual, but is it normal for rings to be so varied - some tight and some being springy and almost loose?

754 · « **Reply #66 on:** April 11, 2010, 11:14:32 PM »

Can you measure the size of the bores (neighbor might help)

Looks like High compression pistons & maybe bigger bore.

egar · « **Reply #67 on:** April 12, 2010, 10:08:16 AM »

If these are some kind of fancy high-output pistons, how would I figure out where to purchase the right size rings? I was hoping everything was stock to make it easy on myself....

egar · « **Reply #68 on:** April 13, 2010, 01:50:37 PM »

Regarding my piston question, the PO said that the bike was bored out to an 800cc or something thereabouts and that he only rode the bike 3k miles at the most before parking it several years ago. My question: If I clean up the carbon on the rings and they look OK is there any reason to replace them since the bike's mileage is so low.
The odomoter reads less than 9k miles overall.

egar · « **Reply #69 on:** May 13, 2010, 06:42:47 PM »

It's been a few weeks since I've posted but I have indeed been working on the motor when time permits. Had to order a piston pin puller (say that three times quickly) to get the pin out. They were frozen solid into the rods. It was even hard to remove them with the correct tool. I did learn from the PO that the pistons are high performance. The rings on some of the pistons are stuck tight to the piston.
The valves were a breeze to remove after having bought a valve spring compressor at Sears.
I will be taking both the pistons valves and finned heads for those two sections to the local CB guru to do the lapping/honing/rings. I don't have the tools nor the expertise, so I figure that this is one section that I will have to cheat and pay someone to do it right.
Meanwhile, I will begin tearing down the forks, buy new fork seals, buy boots (mine disintegrated to dust), and continue cleaning what remains of the motor so that I can begin spraying it with Duplicolor 1615 silver...

[

IMG]http://i485.photobucket.com/albums/rr218/egar_photo/GEDC0318.jpg[/IMG]

Zaipai · « **Reply #70 on:** May 13, 2010, 07:35:13 PM »

Cool, no turning back now!!!

.: Scott :.

754 · « **Reply #71 on:** May 15, 2010, 05:03:53 PM »

Can you please get a measurement across bottom of piston..or the bore..

egar · « **Reply #72 on:** May 16, 2010, 04:56:09 PM »

Oldtimer,

I haven't been on this weekend, so I didn't see your request until now. I measure across the piston and I'm reading 2.5 inches.

Ed G.

egar · « **Reply #73 on:** May 16, 2010, 05:38:30 PM »

Got the two finned sections of the motor clean enough to paint them. I'll post photos at some point. This means Im ready to haul the pistons and valves to Lucien at AL and L and let him work his magic -- and once the bottom of the motor is clean enough to be painted I will finally be ready to put this bike back together. I bought it in Jan 09, so it's been a long time coming.
When my battery box was powdercoated, all the rubber bits were destroyed. I just got the squishy washers this week and just ordered the round flat rubbers that go on the walls of the box to hold the battery in place. I am now realizing that all these tiny details are going to put me way over what I thought I would spend -- but damn, it's so neat watching everthing look new again. It is becoming an obsession.

blake255 · « **Reply #74 on:** May 17, 2010, 08:20:28 AM »

Quote from: egar on May 16, 2010, 05:38:30 PM

I am now realizing that all these tiny details are going to put me way over what I thought I would spend -- but damn, it's so neat watching everthing look new again. It is becoming an obsession.

Yeah, OEM remplacement parts are just as expensive for an old bike as they are for new. I think that realization is what separates the men from the boys when it comes to restorations. It is definitely not cheap!

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Author Topic: 1970 CB750 K0 restoration - going for original (Read 41765 times)

traveler