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CB750 K5 Restoration

I'm moving into the other direction on my cb750 K5, starting to put it back together.
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I have boxes of parts and am scratching my head. How does this thing go back together???

I decided to rip the parts fiche off the local Honda shop's web site.

Thought I'd share.
CB 750 K5 Parts Fiche
 
OK, first the disclaimer…
Some say it’s pretty cheesy to paint an engine whole. Well… It still has good compression, so why take it apart? It just looked like crap.

I have had limited luck painting engines. Like everyone says, it’s all about the prep work. So here I go again.
First I did several passes with degreaser, scrubbing with a long bristle brush, and shooting it with a power washer. Then I did a couple of passes with paint remover and power washing. Scrubbed it again with a long bristle wire brush. Did a bit of sanding to clean up some aluminum oxidization spots, the real visible areas and where I could reach. Blew it off with compressed air. Then wiped it down with acetone. Oh yeah, for all the aluminum covers that will get polished, I took them off and cleaned up the gasket surfaces, then put them back on. The point here is so that I don’t end up scratching my new paint trying to remove old gaskets. After the acetone, I only touched the engine with rubber gloves on. I masked it off, shot it with VHT Engine Enamel , and let it dry for a day. I read a few reviews on different engine paints. Duplicolor got OK reviews, VHT and POR15 got better. VHT was available at the local auto parts store, plus lots of people on the Honda forums said it matched the original Honda case color.

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Now for the tricky part, how to cure it properly (200 degrees for 1 hour). Sure if I had the engine apart, I could cure it in the kitchen oven (while the wife was out… ha ha), but a big inline 4 is not going to fit. So I made my own curing box. I kept the big box from the BBQ we bought this summer, lined it with aluminum foil so it would reflect the heat. Yeah I used Duct Tape, not real heat tape, hoping it could stay together at 200 degrees.

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Cut a hole in one bottom corner for my Heat gun, poked a cooking thermometer in the opposite top corner.

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As you can see, I’m starting out at 63 degrees. There’s also a hole on top so I can regulate the heat by covering it, and so I can see inside. Making sure the heat gun isn’t pointing right at any part of the engine, and I’m not touching the inside of the box. Turned the heat gun on low and watched the temperature climb.

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After about a half hour or so it seemed to top out at 130 degrees. So I kicked it up to high and laid some towels around the bottom edges. The temperature steadily climbed up to 195, now we are cooking! Since my first half hour was only at 130, I let it cook for another 45 minutes or so.

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At some points it got up to 205 and I would open the hole a little. After cooling off an hour or so, the engine was still pretty warm. I did a fingernail test and that paint is as hard as a rock now..
Yippee, I’ll do the top half of the engine this weekend.
 
Last weekend I mounted the engine in the frame (the lay on the side method) and had my wife help me get it up on the center stand and blocks. Then I spent the better part of Sunday polishing.
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Motor looks great with the new paint. I like the laydown method idea. Never really thought to try something like that. Hopefully I won't have to. No frame off restos for me yet. I'll just clean whats there and light the candle.
 
Started working on softening up the rubbers. Doing the Wintergreen Oil/Xylol trick. 50/50 mix and soak for 24 hours and the rubber should come out soft as new.
Got the Wintergreen Oil off of eBay (~$27 for 16 oz) and Xylol from the local hardware store (~$9). From what I've read, it works great. The Wintergreen oil is expensive, but it's much better than buying new intake rubbers at $50 each, plus the mixture can be reused several times.

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Doing the grommets first
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The wintergreen trick is all over the SOHC4.net forum. There's a couple of different ways to do it.

My jar can only hold so much and I haven't done the intake manifolds yet. I've done all the grommets so far and one air box tube thingy (the rubber between the air box and the carbs)

After 24 hours the parts come out pretty swollen, but as the Xylol drys off and the wintergreen oil stays behind they will shrink down to normal size. Of course, the dried crusty rubber is still pretty crusty.

So far the parts I've done have come out real soft. I had some grommets that where like little hockey pucks, now they are more like gummy bears :)

As for the one carb to airbox tube. People on sohc4.net say as they dry out they may deform. So I I'm letting it dry on an old light bulb, so it maintains its funnel like shape. I'll do a post when I'm all done detailing the results.
 
grepper,

The shape of the carb to airbox tubes is critical as they are actually velocity stacks and the carbs will not work properly unless they have their original shape. Makes a big difference.

If you can't get the shape right, then source some new OEM's. Do not even think of using pods as you will spend the rest of your natural life screwing with the carbs to get them to run right. Don't ask me how I know this.
 
Pete, thanks again for the valuable insight.
The carb to airbox tubes were partially collapsed, they did not have a uniform cone/velocity stack shape. In fact, they didn't even have a uniform hardness/softness. After soaking they did bounce back to their cone shape and softness was uniform. Like I said, they are now drying cone down on old light bulbs. So fare they are maintaining their cone like shape. I'm in no hurry to put the air box back together, so I'll let them sit on the light bulbs for many days, maybe even weeks or months.

Just to note, my progress on this project is limited by time and money. As for time, I only have a few hours a week to tinker. I wish I had more, but working full time with a long commute, owning a high maintenance home, and two kids and a wife keep me busy. As for the money part. My budget is tight. I have been selling stuff on eBay to fill up my pay pal account.
I am so grateful for my awesome wife whom I'm building this bike for. She is a librarian and her organization's circulation manager chooses what old books end up on the Book Sale shelf and what gets pitched. She has been garbage picking manuals for me. Last week she grabbed one for me and I just sold it on eBay for $35 :D
 
I hear ya Grepper.
My sitch is a little better than yours but not much. I get to work on projects about 2 hrs a night. After the kids go to bed the wife starts watching some horrible drama show that I can't stand so I go down the shop and pour up a stiff one and work on either skoots or RC airplanes. With a 1900 sqft basement I have a pretty good workspace to do things in. I don't think anyone has extra cash to spend right now, I know I don't.
My 71 is coming along nicely, I expect to put some fuel in the carbys and give her a kick in the next week or so. Might just pull the tank off the 73 to see what happens. The 71 tank needs some serious attention before I can hook it up.
 
OK, a followup on my progress on treating rubber parts. For smaller parts like grommets I'd say don't waist your time, they are softer, but also easier to tare.

Here's my carb to airbox rubbers drying on light bulbs. As you can see, the one on the left is fresh out of the soak and swollen, while the one on the right has been drying for a few days and i back to normal size.
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Squeezing the end that clamps on the carbs.
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Squeezing the end that goes into the air box
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Over all I'm very pleases. The tube that's been drying for several days is firm, but flexible and keeps it's shape well. Before I feared cracking it.

And here's a shot of me Squeezing an intake boot. These where hard as a rock before.
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