Project Honda CB 750 K7 oil spill +?

[Bønne]

Stranger in da house? Well, not in my house really, as this 1977 Honda CB 750 K7, has been living with me since 1988 

Have had some oil spill for some time, I know where it comes from, not a big deal to repair, but the engine has to get out of the frame.

As temperatures have raised to above zero again (I haven´t got any heating in my garage), I thought it was time to get started on this project before the spring comes.

So, I took on my "Thyborøn-habit" (Thyborøn is a small fishing village on the westcoast of Denmark, where all the fishermen are wearing thermal coveralls, or: Thyborøn-habit  ), and started to disassemble the bike.

The bike before I started:


Everything needed to get the engine out is removed:


After a break I went out to take the engine out:


And up on the operating table:


Now there´s space to get cleaned up in the corners... or... there´s not much left... should I disassemble the rest and get the frame sandblasted, metallized and painted? That´s the question...

[MrKiwi]

You've come this far, getting the frame done now would mean you've given the whole bike an overhaul. I'd do it, but then its not my bike 

[Jyrays]

 

[JosepM]

  
Amazing! It must be great to have the ability to give a new life to such beauties!

Congratulations,

Josep

[Two Plugs]

As you might remember, I did the complete overhaul on one of my XLV750R's.
I'll go with Mr Kiwi: you have come this far, I would sandblast the frame too and not repaint it, but powder coat the frame.

Its an amazing bike, that 750 of yours! But is the exhaust the original one?

[Jyrays]

As you might remember, I did the complete overhaul on one of my XLV750R's.
I'll go with Mr Kiwi: you have come this far, I would sandblast the frame too and not repaint it, but powder coat the frame.

Its an amazing bike, that 750 of yours! But is the exhaust the original one?

My 1977 CB500F had 4-4 pipes...

[Bønne]

Thanks for your replies.

...I would sandblast the frame too and not repaint it, but powder coat the frame.

Its an amazing bike, that 750 of yours! But is the exhaust the original one?

Yes, powder coating is of cause a possibility too. But metallizing it like I did with my Africa Twin, will make it last forever, and then it´ll only need an ordinary paint, just to make it black.

Think I´ve now desided to go all the way, so I´ll continue next weekend. I know a guy whose great passion is restoring old Hondas, mostly from the sixties (he´s got a totally restored "Black Bomber" standing in his living room ), I think I´ll have a talk with him about it, he must know a good painter too.

And you´re right, it was an amazing bike when it came in 1968, and it still is! As an old Honda dealer (he has retired now), said to me some years ago: that old CB 750 of yours, the reputation that bike gave Honda back then, is the reason we sell Hondas today!

No, the exhaust is not original, it´s a Motad 4-into-1. As Jyrays CB 500, and several of the other CB Four´s, it was born with 4-into-4. Good looking, but the disadvantage was that the system never got hot enough to burn the waste particles from the combustion, and it rusted from inside... and the weight .

[Jyrays]

Thanks for your replies.

...I would sandblast the frame too and not repaint it, but powder coat the frame.

Its an amazing bike, that 750 of yours! But is the exhaust the original one?

Yes, powder coating is of cause a possibility too. But metallizing it like I did with my Africa Twin, will make it last forever, and then it´ll only need an ordinary paint, just to make it black.

Think I´ve now desided to go all the way, so I´ll continue next weekend. I know a guy whose great passion is restoring old Hondas, mostly from the sixties (he´s got a totally restored "Black Bumper" standing in his living room ), I think I´ll have a talk with him about it, he must know a good painter too.

And you´re right, it was an amazing bike when it came in 1968, and it still is! As an old Honda dealer (he has retired now), said to me some years ago: that old CB 750 of yours, the reputation that bike gave Honda back then, is the reason we sell Hondas today!

No, the exhaust is not original, it´s a Motad 4-into-1. As Jyrays CB 500, and several of the other CB Four´s, it was born with 4-into-4. Good looking, but the disadvantage was that the system never got hot enough to burn the waste particles from the combustion, and it rusted from inside... and the weight .

At mine exhaust was still ok at 1988 when I changed it to CB1100 Bold d'Or 

[MrKiwi]

Excellent I look forward to seeing progress pictures and pictures of the finished product once completed. Cheers...

[Bønne]

Had hoped to get something more done today, but things didn´t go as expected. Among other, late afternoon the refinary couldn´t do without me, so I had to go out there and nurse it for a couple of hours .

I had been washing the engine a bit every day during the week (with S100), as it was standing on the table, and despite the interruptions I managed to get the top of the engine cleaned up today, so it´s now ready for disassembling.



Tomorrow im not at home, so nothing will be done there...

[Two Plugs]

Oh, yes, the Honda Black Bomber, that was something else (tad small for my body size though, lol)

In the late 90ties, doing an building inspection for work, I found an immaculate Goldwing GL1000 Anniversary stored outdoors under a plastic sheet (Condense!!!!), but with all the chrome still in good condition. The owner was willing to sell the bike for 5.000 Dutch Guilders (apr 2.250€) and I still regret it that I didn't make the purchase... I guess it would only take a few months for the bikes chrome and paint to deteriorate from the moist under that plastic sheet.

Anyway... a few years later I found my first XLV750R (the black one), literally a 'barn find' (actually it was a garagebox find)

But I still love those 4 cylinder Honda's from the 70ties!

[Bønne]

Oh yes, there are still bikes out there to be discovered! This picture is from David Silver himself, from his latest trip to the US:



This morning I went to the garage, tilted the engine and took off the oil pan to check the oil strainer:



Not much dirt there...

Turned the engine around again (and gave it a new cloth to stand on), and took off the valve cover:



Cut the camchain and secured it... later I´ll use it to drag the new chain through:



Dismounted the camshaft holder caps... they seemed to be okay after 40 years and 148000 km... :



The camshaft bearings and cams look fine too:



Here we have the "sinners", the rubber seals underneath the camshaft holders (3 out of 6)... :



... which covers six holes in the cylinder head (3 in each side):



At time the rubber seals shrinks a bit and gets "tender" caused by the heat in the cylinder head. They will then start to leak oil out in the middle of the cylinder head, which will flow out around the spark plugs and out around the cylinder head.

[Two Plugs]

At this moment one of the most interesting topics to follow, Bonne! Looking forward to learn about your progress!

[Bønne]

Nice weather today... so when home from work, I went to the garage a while...

Had modified an old spark plug with help from a colleague and did some experiments. What worked was a constant air pressure, then 1 Bar was enough, on the combustion chamber, to secure the valves when taking off the valve springs to renew the oilseals.
Here the old seals:



The old seals was so hard that they broke into pieces when I twisted them off, the new ones just slipped right into place:



And so the springs got in place again...



... then it was "same procedure" on the other three.

Thanks to Rune, my son, for helping getting the spring cotters out and in place again (I was in lack of hands ).

Here´s a picture of the modified spark plug:



And the "compression-tool" for taken off the spring cotters (the tee is to have something to hold on to when pressing the springs down):

[MrKiwi]

It is fun reading this, but I'm not sure my lack of technical knowledge means I can completely understand what it is you are doing.


But thanks, great to see what it is you are doing.