CB750 K0/K1 Hybrid

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cfairweather
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Re: CB750 K-Whatever

#286

Post by cfairweather »

Try Acetone to soften the old gasket and a sharp chisel to scrape it off. I have found a chisel is better and safer than a blade. You do have to be careful using either one.
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Lucien Harpress
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Re: CB750 K-Whatever

#287

Post by Lucien Harpress »

I can see this is going to be a royal pain my backside. Tried some gasket remover, didn't do anything, even minor, after a 5-hour soak. Same with acetone for the same length of time- nothing. The only noticeable results I managed to get were from brake cleaner, and that would let me work about 1-2mm on the edge before it dried out and stopped working.

Ugh. No shortcuts, I suppose.

See y'all again in a couple weeks.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
cfairweather
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Re: CB750 K-Whatever

#288

Post by cfairweather »

Try your heat gun while you scrape.
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Lucien Harpress
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Re: CB750 K-Whatever

#289

Post by Lucien Harpress »

Heat helped, a little bit. I don't think there's going to be much of a silver bullet with this one, though. Put about an hour's worth of work in tonight, went from about 1/4 off to maybe a hair over 1/3.

Thing is, this ain't my first rodeo scraping gaskets. I've just never had one baked on quite this badly before. And what's worse, the base gasket is (obviously) stuck on the bores I'm going to use, and the OTHER base gasket got stuck on the block I ended up using too. So I had to do this twice!

Ah well. I'm throwing every degreaser and solvent remover I have at it in combinations that PROBABLY won't start a fire. It's just gonna take a bit longer than I anticipated.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
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Lucien Harpress
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Re: CB750 K-Whatever

#290

Post by Lucien Harpress »

The good news? The base gasket is mostly off.

Image

The bad news? The bores did not come out completely unscathed. Nothing like any deep gouges, but plenty of scratches. Many more than I'd like. I hate that I had to do it, but short of pushing out the sleeves and decking the aluminum, that's the best I can do.

There's a decent chance they're all shallow enough for the new base gasket to take care of, but I've been looking into gasket treatments, just in case.

Ah well. After some final cleanup it'll be time for paint and I can start gapping some rings.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
cfairweather
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Re: CB750 K-Whatever

#291

Post by cfairweather »

I recommend spraying a thin coat of coper coat on the gasket that goes there and the head gasket. It will help fill in the gouges and help ensure a good seal. Many don't use it but it has served me well over the years. It will be fine.
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CYBORG
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Re: CB750 K-Whatever

#292

Post by CYBORG »

when we replaced the head gaskets on Winston's salt flate bike, we used, used gaskets, and copper coated them. They held juat fine. Even on that engine which had a b;ower on it. I always use it
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
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Lucien Harpress
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Re: CB750 K-Whatever

#293

Post by Lucien Harpress »

Cool beans. I've never used copper coat before, but this kind of seems like the exact purpose to use it for. Thanks!

Once I finish up the last bit of the gasket residue, then it's getting nitpicky with brushes and getting all the nooks and crannies of the cooling fins cleaned up. This bike has had a fairly gnarly leak in the past, so there's about 40 years worth of crud baked into all the crevasses. Air-cooled engines look wonderful, but this single part has been the single most annoying part of this rebuild so far.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
cfairweather
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Re: CB750 K-Whatever

#294

Post by cfairweather »

Lucien- If you have a portable forced air propane heater, I have a very good tip for you. If you don't have one, borrow one from a friend because this tip is important and I don't hear of anyone else suggesting it. The problem with the CB750 is you can't easily go back and retorque the head bolts without removing a lot of parts. It just isn't practical to retorque the heads on that engine. Here is what I have done with excellent results:

1. Torque the head to 6lbs, 12lbs, 18lbs.
2. Use a propane heater to heat the cylinders and head. Get it hot as your can for about 15 minutes or even longer if you like. The goal is to simulate running the bike up to normal operating temperatures. Let it sit over night to cool down.
3. Next day, torque at 18lbs again and you will find some will turn a bit. Then, finish torqueing them to 22lbs. Do not exceed this amount of torque or you will risk snapping a bolt. I had an APE stud snap at 24 lbs.
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Lucien Harpress
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Re: CB750 K-Whatever

#295

Post by Lucien Harpress »

Noted. I do have a heater (heck, it's the only reason I've been able to get any work done this winter!), so I can definitely make this work. Thanks for the head's up!

Speaking of work, I got off my butt and got the clutch cover back on.

Image

I also attempted to clean up the outside of my bores a bit more, and while the outsides look okay, deep down in the crevasses there's still a lot of oil, dirt, gunk, and whatever. Looks like there's going to be another trip to the car wash in my future...
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
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Dr. Frankenstein
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Re: CB750 K-Whatever

#296

Post by Dr. Frankenstein »

Great work, Lucien; I was going to add a Plus-1 (+1??) on the copper spray; I've used it on both my GL1000 builds, and it works great; pretty sticky though right after you spray it. Also what Cedric said about the chisels, Harbor Freight has a great set of wood chisels in varying widths for, like, $9! I sometimes also use the Gunk carburetor/parts cleaner for those stubborn gaskets that just don't want to come off, the stuff that comes in a big paint can with a basket - paint some on with a hobby brush, let it soak and carefully scrape away. It eats rubber gloves, too. Good stuff!

I'm waiting to pick up a '72 CB500F I want to do, I'm going to use this whole thread as a reference! Where did you get the engine studs, and how much were they?
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Lucien Harpress
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Re: CB750 K-Whatever

#297

Post by Lucien Harpress »

The studs were heavy-duty cylinder studs by APE. Common enough that they are available from multiple retailers. Looks like $130-$180, depending on the retailer.

Not much real news from my end. Cleaning continues. I snagged a set of small brushes that fit into an impact driver, so we'll see how that does deep-cleaning the cooling fins.

I did modify my long-term plans a bit. I'd still like to get a set of K0 body panels, but while I was holding out for a K0 frame to put them in, I'm beginning to see how rarely they come up. I was prepared for '69 frames to be ridiculously expensive, but even 1970 frames are thin on the ground and expensive when they do show up. Now I DO have a '71 frame sitting around, but there was some small rust holes and the rear bracket (holds the rear turn signals and rear fender) was broken off, and no paperwork.

Now, a '71 with '70 bodywork is something I can get behind, and I might be able to use the same "loophole" I used on my Honda Dream to get a title. It's still a long shot, but if I'm replacing the frame, now's the time to do it.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
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Lucien Harpress
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Re: CB750 K-Whatever

#298

Post by Lucien Harpress »

Progress continues. I finally got the bores cleaned up well enough slap on some paint. It's not perfect, but short of vapor blasting them (which is what I would've done in the first place if I had infinite cash), this is as good as it's going to get.

Image

Image

Image

I still need to confirm the silver has good coverage, and it needs clear yet, but I'm happy to finally knock this out. This part has been a bear. I can only hope the head is less of a pain, but we'll see.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
User avatar
Lucien Harpress
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Location: Michigan

Re: CB750 K-Whatever

#299

Post by Lucien Harpress »

Things are starting to look a bit more engine-shaped.

Image

Image

Getting the bores on by myself wasn't as bad as I was anticipating. Chock the two inner pistons, slide it on, slowly push in the rings whenever it got hung up, continue until all 4 sets of rings were fully in the bores, then tap it home with a bit of wood. Honestly, making sure I got everything set (cam chain tensioner, guides, o-rings, dowel pins) and didn't forget anything was the hardest part.

Next up? The head. Plan is to strip that down (because I'm in this deep, may as well lap valves too), then do the clean-paint-install song and dance all over again.
1997 Valkyrie- Light Cutomization, but Too Busy Riding
1980 KZ1300- Bike's Haunted
1976 GL1000 (Yellow)- It Runs (Poorly) and Doesn't Leak (Mostly)
1974 Velosolex 3800- Better Than Walking
1972 CB750- Broke the Chain And Ate the Motor
1969 CT90- The Most Fun You Can Have on 90ccs.
1965 CA77 Dream- Needs a Full Teardown, but Complete

All advice I give is only valid until an expert corrects me.
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Rednaxs60
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Re: CB750 K-Whatever

#300

Post by Rednaxs60 »

Looking very good! Looking forward to earring first start.

Have heard that if you are going to do something do it right the first time, always have funds available for a second go round it seems. My neighbour's friend has a 750 Honda, forget the year, that he wants to put back on the road but does not want to do the work. We discussed my projects with my '85 GW Limited Edition and he asked if I wanted another project, never know.
"When writing the Story of your life, don't let anyone else hold the pen."

Ernest

1985 GL1200 Limited Edition
2014 Can-Am Spyder RT LE
2021 Royal Enfield Himalayan
1995 GL1500 SE CDN Edition (sold)
2012 Suzuki DL1000 VStrom (sold)
Ontario 1985 GL1200 Limited Edition (sold)
2008 GL1800 (sold)
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