CB750 K0/K1 Hybrid

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Lucien Harpress
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Re: CB750 K2- Case Study

#226

Post by Lucien Harpress »

Thanks for the offer! I'll be sure to keep you in mind.

I kind of psyched myself out a bit by how I had to take everything apart, what with the piston frozen in the bores as they are. It kind of looks like a "proper" rebuild can be built up into the bottom case, and the top case can just be placed on top of everything.

Regardless, you might be getting some messages and e-mails this winter. ;)
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.
rufuss
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Re: CB750 K2- Case Study

#227

Post by rufuss »

try strong arm fluild worth a try rufuss
Shadowjack
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Re: CB750 K2- Case Study

#228

Post by Shadowjack »

All the Hondas I ever had down that far were reassembled into the upside-down top case, then the bottom case was dropped over it all. Impossible to get the shift forks aligned the other way around.
cfairweather
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Re: CB750 K2- Case Study

#229

Post by cfairweather »

You have choices when you assemble the CB750. You can load the bottom case first, which is my choice, or you can do it per the manual and load the top side first (upside down). The problem with loading the top half first is getting the shifting forks in place without binding. When you do load the bottom half first, you can get all the shifting forks in place and test the operation of the transmission before you place the top half over the bottom half.
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Lucien Harpress
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Re: CB750 K2- I Said I'd Do It

#230

Post by Lucien Harpress »

Image

The weather has finally changed for the colder, and seeing as how most of the work that needed done on it involved paint, I figured it was time to put up the Honda Dream for the season. I got everything for that put away and organized, and dove head-first back into my 750.

I've got work that needs done throughout the bike, but getting the engine out is priority. I MIGHT be able to get that pulled this weekend, but we'll see. Gasket kit is getting ordered tomorrow, and next paycheck I will probably be getting the upgraded cylinder studs. It's a long season, with plenty to do.
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 K2- I Said I'd Do It

#231

Post by Lucien Harpress »

I genuinely forgot how quickly you can tear one of these bikes down.

Image

Image

I was fully prepared to pull the oil tank today too, but I'm going to have to take part of the rear brake assembly first. So that can wait. Still, oil drained, exhaust off, engine one step closer to being pulled. Good progress for the day.

Image

And a better view of the damage. I'm still not 100% sure how I want to tackle this (because that chain is JAMMED in there), but that can wait until the engine is out.
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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flyin900
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Re: CB750 K2- I Said I'd Do It

#232

Post by flyin900 »

Taking it apart is the easy task, as your aware. Take lots and lots of pictures... you can never have too many pictures, or at least I can't have too many. :-D
Current Bikes:

1966 CL77 - Honda 305cc - Dual purpose - "Gentleman's Scrambler" was a period moniker.
1967 CL175K0 - Low production number with #802 engine serial- winter 2019/2020 full restoration.
1972 CB350F - Baby Four with low mileage - Cosmetic refresh to the next level 2021/2022.
1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
1983 CB1100F - Canadian model - DOHC Supersport in pristine low kilometre condition from new.
1984 GL1200 - Standard model in showroom condition - two owner bike from new.
1984 CX650E - Restored summer 2017 - a rare Eurosport model - excellent one owner bike.
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Lucien Harpress
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Re: CB750 K2- I Said I'd Do It

#233

Post by Lucien Harpress »

Oh, don't I know it. I've got a whole folder on my phone for my Dream, just in case. :lol:

Luckily, I have the advantage with the 750 of having had it all apart before. Since I built the whole bike essentially from parts, there's very few fasteners I've had to struggle with so far. Now, once the engine is out, however? THAT'S a whole 'nother story. Speaking of which...

Image

I'm pretty much ready to pull the motor. The only thing really stopping me is seeing if it would be a good idea to pull the header attachments or not, AND remembering how much of a pain getting it out last time was.

Ah well. I'll figure something out, and figure in the next day or two being able to get it out. Until then!
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.
Shadowjack
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Re: CB750 K2- I Said I'd Do It

#234

Post by Shadowjack »

How do you like that Kawasaki moose in the background?
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Lucien Harpress
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Re: CB750 K2- I Said I'd Do It

#235

Post by Lucien Harpress »

My 1300? I love the big KZ to death- the few times I've been able to take it out. It's never been 100%, and the minor issues seem to change every time I go back to it. Still, apart from being a bit top-heavy (and just stupid heavy all around), it's great. Solid, plenty of power, sounds like a beast when you get on the throttle, and very pretty (if you're a fan of edges and hard corners).

The plan is to hit it hard this summer after my 750 is back together. That way I can split my time between assembly of my Dream and troubleshooting with the KZ. I really, really, REALLY hope one day it'll get sorted.
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 K2- I Said I'd Do It

#236

Post by Lucien Harpress »

Good news? I managed to get my engine out.

Image

Image

The bad news? I got the chain off, and I don't think JB Weld is going to cut it.

Image

I didn't break anything further- I just pulled out all of the already loose pieces. It's... not great. Thankfully, I've still got all the internal parts from my donor engine in case I need to use them. I always knew this was going to be fun....
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 K2- Engineering Progress

#237

Post by Lucien Harpress »

Motor is up on the operating table, and progress has been swift.

Image

Image

Image

Overall, things were cruising along well. I'd had the cam out before, but I've got a feeling somebody else has been at least as deep as having the head off- it came apart surprisingly easy for a 40 year old engine. AND it was missing some o-rings. In any case, I'm glad I've got the chance to re-do things. Pistons and valves looks good, although I AM going to clean them up and probably re-lap them. I was feeling good.

Which of course meant I HAD to do something to fix that.

Image

The bores were quite stuck, and if anyone's wondering, this is NOT the place to tap on with a piece of wood. Still, could be worse I suppose. I'll be putting some feelers out to see if anyone can weld it back on. I could just leave it, but it would drive me nuts if I did.
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 K2- Engineering Progress

#238

Post by cfairweather »

Lucine- Did you remove the oil orifices? If not, you need to remove these and clean them.
These orifices must be removed and carefully cleaned or you will risk ruining your engine when it goes back together. This easy procedure has been tested on the early style orifice and the later style. You do not need heat or a bent wire to remove them; just use the miracle of hydraulics and they will come out with no damage to the head or the orifice. First, you need to tap the hole that is right next to the orifice. Use a 1/8-27 size tap which is the size for most grease gun hoses. This tap fits perfectly in the hole and you can easily create threads with no drilling. The threads will not damage the head.
After you have threads, plug the bottom of that hole with a short piece of rubber hose, with a screw plugging the end of the hose, or you could use duct tape across the hole. Make sure the head is on a flat surface to help seal the bottom of the plugged hole. We want all the grease to be forced into the port that goes to the orifice. Attach your grease gun to the threaded hole. Put on your safety glasses as grease might shoot out of the orifice and squirt you in the eye. Use rubber gloves and use your finger to close the orifice hole. As you pump grease, it will be unable to get through the orifice hole because you have it blocked with your finger, so it will have nowhere to go. What happens is the grease pressure is evenly applied to the underside of the orifice and it will be pushed out of the hole. It will come out slowly with each pump.

Also, spend $120.00 on new heavy duty studs. The originals stretch and are too weak. With the APE studs, you can torque the head to 21 lbs. Retorquing the head bolts on these is not practical, but I will share with you how I do this without starting the engine. What I do is torque the nuts to 6-12-18 lbs and then use a propane heater to heat the engine. I just hold the heater in my hands and heat the engine fins up to about the normal temperature of a CB750 and then I let it sit overnight. Next day, I do 18 lbs torque again and some of the nuts will probably turn a bit. Then I do the final value of 21 lbs.
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Lucien Harpress
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Re: CB750 K2- Engineering Progress

#239

Post by Lucien Harpress »

Thanks for the heads up about the oil orifices. I knew nothing about those beforehand, so I'm glad I know what to keep an eye out for on my way back through.

The heavy-duty API studs are DEFINITELY happening. This engine already exhibited the classic slow oil leak around the head, and while I see now a missing o-ring probably didn't help things, you're right in that now's the time to do things correctly.

I'm getting close to cracking the bottom end, but I need to organize and catalog some stuff first. Pistons, head, bores, etc. I can see the shifter actuating mechanism is going to be a nightmare (as I still haven't completely wrapped my head around how it works), so I'm taking that part SUPER-slow. Thing is, I still have to clean the donor cases too, so I can afford to take my time.
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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Location: Cheyenne, Wyoming

Re: CB750 K2- Engineering Progress

#240

Post by cfairweather »

I would not remove the rods from the crank unless you were having problems inside the engine. I would replace the rings and hone the cylinders. It is also a good idea to replace the cam chain with a heavy duty type and if the tensioner is hard or is damaged, replace it.
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