Author Topic: 1976 Honda cb750K  (Read 26183 times)

0 Members and 1 Guest are viewing this topic.

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #200 on: January 04, 2024, 10:18:38 AM »
I pay about $20/ 4 litres for the stuff I buy. Wear eye protection!
My local farm supply store doesn't carry phosphoric acid. Only muriatic acid at $19/4L. Will call around.

Bill….. Try Amazon.ca. This looks the same to me?
« Last Edit: January 04, 2024, 01:31:38 PM by BenelliSEI »

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #201 on: January 04, 2024, 01:18:30 PM »
Not sure I picked the right tank, but it had some wear marks that match skuffs on the frame……

Found the missing oil line and gave them a good scrub. When they are totally dry I mix a bit of paint thinners and a flat black paint and give the material covering on them a quick coat.
« Last Edit: January 04, 2024, 01:29:56 PM by BenelliSEI »

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #202 on: January 04, 2024, 01:19:47 PM »
Next up is to scrub down the main wiring harness and do a few small repairs. Dismantled the airbox today and astounded by how hard the velocity stack/ carb connector rubber bits have become. I had to carefully cut them up to get them out. Absolutely rock hard.

Note the bit of towel under the brake hose to metal line connection. Spotted a tiny drop of BF hanging there. I hate doing stuff up too tight, but 1/8 of a turn more solved the problem.
« Last Edit: January 04, 2024, 01:30:24 PM by BenelliSEI »

Offline Nightshift

  • Full Member
  • *
  • Posts: 43
  • Semi-elderly
Re: 1976 Honda cb750K
« Reply #203 on: January 04, 2024, 02:56:39 PM »
I pay about $20/ 4 litres for the stuff I buy. Wear eye protection!
My local farm supply store doesn't carry phosphoric acid. Only muriatic acid at $19/4L. Will call around.

Bill….. Try Amazon.ca. This looks the same to me?
Hmmm, not sure John. It doesn't indicate what grade it is but for $26/4L I'm guessing its watered down when it only lists it as a concrete/grout cleaner. The Food Grade stuff at 85% or even 75% is $140/gal and it does indicate its a rust remover. Gotta do some more homework to make sure I'm buying the right stuff.
Can someone update me a what's offensive today? It's really hard to keep up!

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #204 on: January 04, 2024, 06:04:28 PM »
I pay about $20/ 4 litres for the stuff I buy. Wear eye protection!
My local farm supply store doesn't carry phosphoric acid. Only muriatic acid at $19/4L. Will call around.

Bill….. Try Amazon.ca. This looks the same to me?
Hmmm, not sure John. It doesn't indicate what grade it is but for $26/4L I'm guessing its watered down when it only lists it as a concrete/grout cleaner. The Food Grade stuff at 85% or even 75% is $140/gal and it does indicate its a rust remover. Gotta do some more homework to make sure I'm buying the right stuff.

Good point. I’ll check what concentration my stuff is, next shop day.

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #205 on: January 04, 2024, 06:17:02 PM »
Darn….. Had two oil tanks on the shelves and Stu tells me I fitted the wrong one! Will  redo it next time. Now I will have two really clean tanks. The second one will go on the Rickman soon enough.

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,572
  • Bike almost back to the 70's 2015
Re: 1976 Honda cb750K
« Reply #206 on: January 04, 2024, 11:08:28 PM »
Breather spigots and hose thicker on K6 than earlier.
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 BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #207 on: January 05, 2024, 08:29:27 AM »
I pay about $20/ 4 litres for the stuff I buy. Wear eye protection!
My local farm supply store doesn't carry phosphoric acid. Only muriatic acid at $19/4L. Will call around.

Bill….. Try Amazon.ca. This looks the same to me?
Hmmm, not sure John. It doesn't indicate what grade it is but for $26/4L I'm guessing its watered down when it only lists it as a concrete/grout cleaner. The Food Grade stuff at 85% or even 75% is $140/gal and it does indicate its a rust remover. Gotta do some more homework to make sure I'm buying the right stuff.

Bill…… Here iswhat I have. Can’t find the acid % anywhere on the label. Will be interested in your conclusion.

Offline Nightshift

  • Full Member
  • *
  • Posts: 43
  • Semi-elderly
Re: 1976 Honda cb750K
« Reply #208 on: January 05, 2024, 09:21:08 AM »
Thanks John for digging that out. Here is the MSDS for that product. Looks like its a blend of phosphoric and nitric acid. Note they say its not compatible with aluminum, mild steel (gas tanks), etc. Cheers, Bill
Can someone update me a what's offensive today? It's really hard to keep up!

Offline grcamna2

  • Not a
  • Really Old Timer ...
  • *******
  • Posts: 15,148
  • I love to restore & travel. Keep'em Going Strong !
Re: 1976 Honda cb750K
« Reply #209 on: January 05, 2024, 09:26:39 AM »
Thanks John for digging that out. Here is the MSDS for that product. Looks like its a blend of phosphoric and nitric acid. Note they say its not compatible with aluminum, mild steel (gas tanks), etc. Cheers, Bill

Can it be slightly diluted in strength to allow you to use it in your fuel tank safely ?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #210 on: January 05, 2024, 01:44:08 PM »
Thanks John for digging that out. Here is the MSDS for that product. Looks like its a blend of phosphoric and nitric acid. Note they say its not compatible with aluminum, mild steel (gas tanks), etc. Cheers, Bill

Bill….I don’t use it on aluminum. I dilute it at least 12:1 and it works fine in tanks too. Thanks for the sheets, I printed them off for info in the shop!
« Last Edit: January 11, 2024, 04:44:41 PM by BenelliSEI »

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #211 on: January 05, 2024, 01:53:24 PM »
Finished up all the electrical today and forgot to take a picture. Looks tidy.

Stripped down the airbox and threw all the black plastic in the dishwasher.
Apparently they “stink”?
« Last Edit: January 06, 2024, 10:00:31 AM by BenelliSEI »

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #212 on: January 06, 2024, 01:06:40 PM »
Electrics  back in place. Need to find a ground cable and test everything next time.
« Last Edit: January 06, 2024, 01:09:03 PM by BenelliSEI »

Offline denward17

  • Expert
  • ****
  • Posts: 1,391
Re: 1976 Honda cb750K
« Reply #213 on: January 06, 2024, 01:16:52 PM »
^Very clean look, great job John.

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #214 on: January 06, 2024, 02:59:06 PM »
^Very clean look, great job John.

Thanks Den. Looks like you were doing the same today! There is a very small bit of rust and “scale” on this bike, but it’s so good I’m determined to preserve all the original finishes.

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,572
  • Bike almost back to the 70's 2015
Re: 1976 Honda cb750K
« Reply #215 on: January 06, 2024, 11:40:54 PM »
John, do you have the long breather hose to this bike?

I have not found a stock hose.
From valve cover back to passenger footpeg + a little down.

I have ordered 5m NBR hose, ID 10mm, OD 14mm from China (eBay).
I do not have the rear bracket for my K6.
Saw old photos that I used a strap aroubd rear triangle and hose that was dry and hard.
Bracket went with the 341 4-4 40 years ago.
My K2 will probably get a longer hose too, T- connection with oil tank breather.
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 BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #216 on: January 07, 2024, 05:09:52 AM »
John, do you have the long breather hose to this bike?

I have not found a stock hose.
From valve cover back to passenger footpeg + a little down.

I have ordered 5m NBR hose, ID 10mm, OD 14mm from China (eBay).
I do not have the rear bracket for my K6.
Saw old photos that I used a strap aroubd rear triangle and hose that was dry and hard.
Bracket went with the 341 4-4 40 years ago.
My K2 will probably get a longer hose too, T- connection with oil tank breather.

Per….The hose was on the bike and in good shape. It is a long one and is very thin wall. Want me to take measurements?

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,572
  • Bike almost back to the 70's 2015
Re: 1976 Honda cb750K
« Reply #217 on: January 07, 2024, 05:16:12 AM »
John, do you have the long breather hose to this bike?

I have not found a stock hose.
From valve cover back to passenger footpeg + a little down.

I have ordered 5m NBR hose, ID 10mm, OD 14mm from China (eBay).
I do not have the rear bracket for my K6.
Saw old photos that I used a strap aroubd rear triangle and hose that was dry and hard.
Bracket went with the 341 4-4 40 years ago.
My K2 will probably get a longer hose too, T- connection with oil tank breather.

Per….The hose was on the bike and in good shape. It is a long one and is very thin wall. Want me to take measurements?
That would be fine ;)
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 BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #218 on: January 08, 2024, 12:19:36 PM »
John, do you have the long breather hose to this bike?

I have not found a stock hose.
From valve cover back to passenger footpeg + a little down.

I have ordered 5m NBR hose, ID 10mm, OD 14mm from China (eBay).
I do not have the rear bracket for my K6.
Saw old photos that I used a strap aroubd rear triangle and hose that was dry and hard.
Bracket went with the 341 4-4 40 years ago.
My K2 will probably get a longer hose too, T- connection with oil tank breather.

Per….The hose was on the bike and in good shape. It is a long one and is very thin wall. Want me to take measurements?
That would be fine ;)
[/


Per….. The hose that runs from my cam cover vent to the right side passenger foot peg is the original hose. It’s approximately 15mm OD. and has a 3mm wall thickness. OA length is about 92 cm. Happy New Year, John D.

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #219 on: January 08, 2024, 12:20:53 PM »
Finished up the airbox this afternoon and added new rubber connectors/velocity stacks from vintagecb750.com. They are very soft and pliable and fit perfectly. Meguire’s “Back to Black” polish sure makes a clean ‘box shine!

Also cleaned out the correct oil tank! Photos next time.
« Last Edit: January 08, 2024, 12:47:55 PM by BenelliSEI »

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,572
  • Bike almost back to the 70's 2015
Re: 1976 Honda cb750K
« Reply #220 on: January 08, 2024, 09:13:34 PM »
John, do you have the long breather hose to this bike?

I have not found a stock hose.
From valve cover back to passenger footpeg + a little down.

I have ordered 5m NBR hose, ID 10mm, OD 14mm from China (eBay).
I do not have the rear bracket for my K6.
Saw old photos that I used a strap aroubd rear triangle and hose that was dry and hard.
Bracket went with the 341 4-4 40 years ago.
My K2 will probably get a longer hose too, T- connection with oil tank breather.

Per….The hose was on the bike and in good shape. It is a long one and is very thin wall. Want me to take measurements?
That would be fine ;)
[/


Per….. The hose that runs from my cam cover vent to the right side passenger foot peg is the original hose. It’s approximately 15mm OD. and has a 3mm wall thickness. OA length is about 92 cm. Happy New Year, John D.
Thank you for the hose details good to know.
I have found a nitrile hose ID 10mm, OD 14 that I hope will work without kinks.
5m
I think it will sit tight enough on valve cover spigot, a strap will help.

https://www.ebay.com/itm/175723417741?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=DB4AXMZjTt6&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY

My K2's airbox might get some black polish too. It is my K6 original box ;)
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 BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #221 on: January 10, 2024, 08:05:54 AM »
Per….. That looks like a good solution. It’s hard to find the right “thin wall” pipe. One of the guys I race with runs a very busy, local garage. They do a lot of FORD truck engine replacements. The new ones come crated with all the electronics, ECU and hoses. I always strip out all the vent and fuel lines before the old ones get scrapped! Lots of good stuff and free!

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,572
  • Bike almost back to the 70's 2015
Re: 1976 Honda cb750K
« Reply #222 on: January 10, 2024, 08:31:26 AM »
I'll report how it will work.
My K2 might be updated to K6 long breather style too ;)
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 BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #223 on: January 10, 2024, 11:40:36 AM »
I'll report how it will work.
My K2 might be updated to K6 long breather style too ;)

Per….. I fitted the “correct” oil tank today (top in photo). It only has one hose from the tank that goes back to the rear vent on the transmission casing. The internal pipe in the tank goes up pretty high inside, so I guess in theory, if the tank is over filled, it will also act as an overflow. The only true vent is the long pipe from the cam cover, back to the right passenger foot peg. I wonder if that is enough?
« Last Edit: January 10, 2024, 11:44:12 AM by BenelliSEI »

Offline BenelliSEI

  • Really Old Timer ...
  • *******
  • Posts: 9,932
  • 1969 cb750
Re: 1976 Honda cb750K
« Reply #224 on: January 10, 2024, 11:45:30 AM »
Fitted the correct oil tank today and finished up the airbox, including a new filter. Went through my notes and I did fork seals and fork oil back when I bought it. Only rode it 28 miles before borrowing the motor for the Rickman…….
« Last Edit: January 10, 2024, 12:00:00 PM by BenelliSEI »