Author Topic: CB750 K6 motor rebuild and cosmetic restore.  (Read 3346 times)

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Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #25 on: November 30, 2021, 04:28:47 AM »
Well, I guess I'm just not hearing the music yet.

Item #1
It continues to run rich, would not start yesterday, pulled #4 plug. It was carbed up, soooo I took out all & replaced with D7EA plugs. These are one range hotter, hoping this helps the issue. If not I'll look at the float setting again, maybe this time set a mm higher on the floats, 27 vs 26 mm.  Amazing how well it starts on new plugs!

Item #2
Starter has started spinning without turning the motor over. choices are:
Buy a set of stiffer springs
Buy a Kit from K&L that replaces the springs, caps and rollers
Buy both and install

I want to take it to Ft Myers in January for a month, hoping to be thru this debug stage by then.

This is a picture of the clear protection I put on the tank to prevent the seat from scratching the paint.  the original tank was worn to the silver base coat of the original paint.
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline MauiK3

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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #26 on: November 30, 2021, 02:23:19 PM »
Have you used the clear tube method of checking floats?
Mark Paris’ book has a great section on carbs. One part talks about a little burr that can develop around the float bowl pivot that can cause the float to stick sometimes. It can be cleaned up to fix the problems.
His book is a must have for these bikes.
1973 CB 750 K3
10/72 build Z1 Kawasaki

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #27 on: December 01, 2021, 05:18:29 PM »
I have not set the floats via tubes, I have seen the part here and on eBay, but sold out before I got to purchase.

One "good" thing is all four plug were similar in carbon build up, I think this means all the floats are about the same, Butthoonose?

I have Marks book available to me as a friend bought it. It is a handy reference book.
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #28 on: December 15, 2021, 05:45:05 PM »
Today I disassembled the sprag clutch and fixed what I think was causing the starter to be erratic.

I found the capture plate between the bronze roller cage & the rotor body was worn and bent at one of the roller locations. The indentation must have caused it to hang up.

I flipped the part over and hammered it flat/ then sanded smooth. Installed new springs, pushers and rollers although I am not sure they were needed.

Runs smooth by hand and with the starter motor. Warm here tomorrow so I will take it for a ride to test it.

I have also  installed a DVM and USB port; pic attached.

I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline PeWe

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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #29 on: December 16, 2021, 04:05:46 AM »
You will get the charging system function verified with that DVM.
Max voltage with fully charged battery.
Where the low/high charge will happen.
My bikes flips over to  higher at around 4000 rpm. It will stay until around 3600rpm when it flip over.
After a lower speed city riding with headlight on, use of blinkers and brake light  it will take a while until you'll see +14V again.
Better road at 5000-6000 rpm can need  20 minutes or more.

Be careful when riding and do not watch that DVM too long. Focus on the road and all car drivers out there that want to kill you by their ignorance or not existing care about others.
I know.... ;D
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #30 on: December 16, 2021, 11:02:53 AM »

Be careful when riding and do not watch that DVM too long. Focus on the road and all car drivers out there that want to kill you by their ignorance or not existing care about others.
I know.... ;D

Sound advice for all moments on two wheels among the two ton(+) beasts.
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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  • Posts: 183
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #31 on: December 17, 2021, 04:54:08 AM »
Took it on a nice 60 mile ride yesterday.  This was the first ride where I have zero concerns after the ride. It runs great, burbles a little below 2000, then pulls hard all the way to red line. It rides and handles great, as I've thought for some time it is the right size and power for me. A Joy to zip around the back roads and city streets.

Only excitement was a two wheel slide doing a quick 90 degree turn, assume it is the new tires not being broken in around the "chicken" strips. Thought I was going to slip into a car in the other lane for some fraction of a second; a RH foot dab brought her back up and off I went straight down the street. Does it matter if it is luck or skill?  ;D


Replacing the RH control on my Goldwing now...Dirty under the garnish!
Glad I'm not paying $100/hour to do this repair.
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
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  • Posts: 183
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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #32 on: May 18, 2022, 03:00:21 AM »
Took it on a nice 100+ mile ride yesterday on my way to get my haircut. Stretched out what is a minimum 30 mile ride from out here in the boonies.  It has 600 miles on the motor now so I pressed it to redline for the first time.  It pulls great from about 6K, continues to please me with how well it rides now.

Under the "always something" category:

The Neutral light is now always on.  I outsmarted myself by replacing the retaining hex bolt with a SHCS. 

The High Performance clutch still chatters just off idle.

I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline newday777

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Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #33 on: May 18, 2022, 04:52:50 AM »
Yes the Wings do get dirty under the garnish..vacuum created under there at speed. My 08 is the same.
Good to hear the K6 is getting some miles and you were able to stretch her out finally.
I picked up an 836 motor that has a few extras in it to put in my K6 long term project. It appears in low miles condition but I need to clean out the insides and inspect it as the oil pan was off but protected. Then while apart I'll vapor blast and paint the motor as it came to me red, black and pitted chrome....the chrome may get redone or my K6 motor covers will get polished...
But my time is limited as work is happening 1st and my K5 is on the lift for maintenance and I also picked up some project carcasses to go through as a couple guys are interested...
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
  • Enthusiast
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  • Posts: 183
  • Always looking for SOHC people to ride with in NC
Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #34 on: May 18, 2022, 02:36:41 PM »
Great collection, love the "D" fence oil shield!

What year T'bird is that?
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976

Offline newday777

  • Really Old Timer ...
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  • Posts: 5,248
  • Avatar is my 76 K6 in Colorado w/Cody on back 1980
Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #35 on: May 18, 2022, 07:03:35 PM »
Great collection, love the "D" fence oil shield!

What year T'bird is that?
D fence oil shield??

1966. It was stored by someone over the winter.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline markmyodb

  • Honda owner since 1969. 19 Honda motorcyles, cars, and lawn mowers through the years!
  • Enthusiast
  • **
  • Posts: 183
  • Always looking for SOHC people to ride with in NC
Re: CB750 K6 motor rebuild and cosmetic restore.
« Reply #36 on: May 19, 2022, 03:10:05 AM »
I tell my wife the motorcycles are an investment...

CB550K1: 1975
CB750K6: 1976