CB750 K0/K1 Hybrid

Discuss anything about other motorcycles, accessories, riding gear and other motorcycle related topics.

Moderators: Whiskerfish, ascot, Forum Moderators

Post Reply
cfairweather
Silver Member
Silver Member
Posts: 683
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: CB750 K2- I Miss Shaft Drive

#211

Post by cfairweather »

What was the tensile strength of the chain when you bought it? If it was one of the low end DID chains, they are only about 6930 pounds. So many chains have broken the cases on CB750s and it is because of poor quality chains. The minimum DID chain for a CB750 would be a NZ model which has a tensile strength of 8600 pounds. This is the one I selected for my last CB750 project and after seeing your post, I am going to order a new chain of better quality to replace it. One that has 9000+ pounds and with a riveted master link. The one I have now has a removable master link. I am also going to get new sprockets for that bike and plan to use 18/45 instead of the 18/48 to lower the highway RPMs a bit. Good luck.
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- I Miss Shaft Drive

#212

Post by Lucien Harpress »

I'll be 100% honest, I have no idea. Knowing me I googled "CB750 Drive Chain" and bought one in the price range I could afford (which is probably the lower end).

When I do it again, I'm probably going with the riveted master link as well. 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
robin1731
Membership Admin
Membership Admin
Posts: 21724
Joined: Mon May 29, 2006 8:31 am
Location: Decatur, Indiana

Re: CB750 K2- I Miss Shaft Drive

#213

Post by robin1731 »

I ran regular master link chains on the drag bikes for years. I never broke a chain. Quality chain and good maintenance are key. In the pic with a short piece of the chain hanging down you can see it had tight spots. Maybe from too tight. Maybe from lack of lube. I use chain wax, not lube. Less mess.
1976 Goldwing Super Sport
1985 Honda Elite
1976 KZ900 Dragbike
1992 ZX7 Dragbike (KZ900 style motor w/NOS)
and a rotation of various purchases
Randakk approved Carb Rebuilder
cfairweather
Silver Member
Silver Member
Posts: 683
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: CB750 K2- I Miss Shaft Drive

#214

Post by cfairweather »

I have never had a chain break either and I agree the quality of the chain and keeping it lubed are the most important things; however, the clipped master link seems to be involved with a lot of the chain failures. The highest quality chains don't typically offer a clip style master link. Notice that Lucien mentioned that his master link was MIA. When I was young and broke, I used to use chain from a John Deer Dealer to save money. Seemed like the size was a "50" if I recall correctly. These used a clipped master link and the chain size was close enough to work on the 530 sprockets. I used these chains on my 1970 CB750 for many years and never had any issues. I think the bike had about 60,000 miles on it when I got rid of it. I know, it was a bad idea, but I was broke and it saved me a few bucks. :)
Shadowjack
Silver Member
Silver Member
Posts: 654
Joined: Fri May 26, 2017 11:07 am

Re: CB750 K2- I Miss Shaft Drive

#215

Post by Shadowjack »

Once power levels reached over about 50-60 hp, manufacturers started using endless chains. Probably a cause and effect there. I think the early CB750 failures probably resulted from still having master links. Many small bikes still use them.
cfairweather
Silver Member
Silver Member
Posts: 683
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: CB750 K2- I Miss Shaft Drive

#216

Post by cfairweather »

Since my last post I did some research and decided to buy a DID 530VX3 chain for my current 1971 CB750 project and I ordered a rivet style master link for my other CB750 that uses a DID 530NZ chain. I also ordered the DID KM500R tool to break and rivet the master link. This tool is very expensive (about $120.00), but it has great reviews. Lucien, consider the 530VX3 when you buy a replacement chain as this chain is very strong (9200 pounds) and it won't stretch much. You can save some money with the 530NZ, but I would make it endless. It comes standard with the clip style master link but has an optional rivet link for an extra $10.00.
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- I Miss Shaft Drive

#217

Post by Lucien Harpress »

I finally wrestled my spare block inside. Not ENTIRELY sure why- it was locked up every since I brought it home, and has been outside, uncovered, in the rain for several years. Still, I don't need it to work- I just need to get it apart.

Image

Pre-chain break I was planning on using the valve cover anyway, to try to stem the massive oil leak from the tach drive. It just looks like I'm going a bit deeper than I was anticipating. I don't plan on getting too crazy with it until later in the year, but I figure it's not to early to get it soaking in some rust penetrant. Still, I'm kind of curious at just how bad the inside of this looks. Guess I'll find 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.
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- Oh My

#218

Post by Lucien Harpress »

I had a bit of down-time on my Dream project, and seeing as it was a holiday (even though I got to work regardless), I figured I'd start picking at my locked-up engine, start getting that apart. The goal was to at least get the head off, and well- kids, this is why you don't leave an engine outside, uncovered.

Image

(In my defense, this motor has been locked up since the day I brought it home. That said, I'm sure my leaving it out didn't help things. Good news, I don't need any of these parts. Bad news, I'm going to have a TIME separating it from the parts I DO need. Oh well. Problem for FUTURE Mike. Er, me.)
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
flyin900
Gold Member
Gold Member
Posts: 1489
Joined: Sun Jan 10, 2010 3:50 pm
Location: Canada

Re: CB750 K2- Oh My

#219

Post by flyin900 »

Well at least it is dry in there. Just not sure what all that stuff is with the two different colours of ??? material. action1
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.
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- Oh My

#220

Post by Lucien Harpress »

Three, if you count the dirt and crud in pots 1 and 4...
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
Silver Member
Silver Member
Posts: 654
Joined: Fri May 26, 2017 11:07 am

Re: CB750 K2- Oh My

#221

Post by Shadowjack »

You will never get those pistons out without pressing them. Aren't you glad you can pull the bottom case and remove the rod bolts to get the barrels off with pistons inside? Or not...😏
User avatar
pidjones
SUPER BIKER!!!!
SUPER BIKER!!!!
Posts: 3237
Joined: Wed May 22, 2013 4:06 pm
Location: East TN

Re: CB750 K2- Oh My

#222

Post by pidjones »

All I can think is to mark where each piston is (after cleaning what you can from above the cylinders), put the head back on with valves but no cam, and put adapters with grease nipples on the top two, then grease gun and hydraulics. May be a fruitless effort, but might jack the jugs off the case.
"Love 'em all.... let God sort 'em out!"
Ex 2006 GL1800 - the Black Pearl SOLD! to make room for:
2021 Can-Am Spyder RT Limited Dark Chalk Metallic
1975 Red GL1000 project - ex Pistol Pete project
1972 Triumph T150V Trident rescue - finished and FOR SALE!
1976 Yamaha RD400c
1978 GL1000 with '75 engine - the Hunley
Ex 1978 GL1000
Ex 1979 GL1000
Ex '79 CB750F rat bike
Ex '86 SEi
Ex '77 GL1000
Ex '76 RD400
Ex '72 Penton 125 set up for flat track
Ex '73 RD250
Ex '68 TR6C - chopped
User avatar
Lucien Harpress
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- Oh My

#223

Post by Lucien Harpress »

Yeah, I've got a couple months to play with it to see what I can get it to do. Spare motors come up often enough that it's an option I've always got in the back of my mind, so if this becomes more trouble than it's worth I can bail on it. I never figured it'd be easy, but.... eh, 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
Honored Life Member
Honored Life Member
Posts: 4077
Joined: Sat Dec 24, 2011 11:41 am
Location: Michigan

Re: CB750 K2- Oh My

#224

Post by Lucien Harpress »

Well, easy part is done.

Image

As you can see, they're not 100% stripped, and the cylinder head studs will be getting replaced as well, but we're farther than I kind of expected to be with this engine. I took vague notes as parts came out (and I still have all/most of them), but as the plan is to re-use all the internals of my current engine, I figured I learn how to do it correctly once THAT one comes apart.

I've never done a bottom end before, and while things don't look impossible, it's going to be an adventure. Mostly making sure all the bearings, o-rings, and clips are where they're supposed to be before closing everything up, and correct order of assembly. I've got a Clymer's manual, but on the other hand... Clymers.

Oh well. One step at a time, once I get there.
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
Silver Member
Silver Member
Posts: 683
Joined: Sun Apr 13, 2014 10:37 pm
Location: Cheyenne, Wyoming

Re: CB750 K2- Case Study

#225

Post by cfairweather »

Lucien- I have done several of these 750s and am currently rebuilding a 1971 K1 CB750. I just finished putting the last engine cover on it today and will be testing it this week if things go well. If you need help, send me a PM as I might be able to help answer some of your questions.
Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “General Motorcycle Forum”