Starting Honda cafe bike build today

I now have the frame and engine apart.
I just layed the frame on its side and lifted the frame right off by myself.
It was very easy.
I have cut many things off of the frame and sanded the frame in those areas with a 100 grit flap wheel to prepare it for powder coating.

 

Below is a detail photo.
I removed that center stand mount tabs also. I want to get the weight of this bike as low as possible. I will have to wait to get the seat to find out if the rear of the frame needs any welding.

I also removed the bearing races to prepare for installation of tapered bearings.

 

I have been cleaning years of grease dirt and layers of spray paint to get to the aluminum.
This engine had 28,000 miles and I did not want to rebuild it if it was not necessary.
I might have to anyway.
There was a LOT of grease on the front of the cylinder heads and I noticed that there were no copper sealing gaskets on the exhaust when I removed them.

 

This dremel wire brush tool works really good for cleaning the engine case. Only problem is that they cost $4.00 and only last about 20 minutes at low speed.

I removed the breather cover to clean it and found this hole in the cylinderhead cover near the cam.
I does not seem like the cam chain could rub this hole in the cover because the cam would have to shift sideways a long way to contact the case.
I almost looks like a defective casting but it could put a lot of oil out the breather tube.
I will be removing the valve cover to put on another valve cove I have that is not covered with black spray paint and then I can get a better look at the inside of the case and find out what is going on.

Back to the cleaning and scraping !

 

Well I found out about that hole in the valve cover.
The casting was made that way.
There was no damage inside the cover.
The valve covers ARE different from the 1978 and earlier models.
This is a photo of the earlier model. It does not have the same venting as the later model. The later model vents are smaller.

 

Well I found out about that hole in the valve cover.
The casting was made that way.
There was no damage inside the cover.
The valve covers ARE different from the 1978 and earlier models.
This is a photo.
And the later model(1978)
My cams looked in good shape for 28,000 miles.

 

One again I'm verry interested in one of your builds...

 

Thanks for the interest.
I do not know what caused all the double posts.

i will try to correct the problem.

 

I have a 1978 Honda CB750K.
It is a 1978K model.
The sprockets were 15-41 stock making it 2.7:1 ratio.
The problem was that the sprockets were massive and heavy.
They were the #630 sprockets and chain.

I wanted #520 sprockets and chain.
Yamatoya Motor Sports was VERY helpful to get me the right sprockets.

I got the #530 sprocket and it was very well made and fit like a glove.
It was a JTF 288-17 It was made to fit early models 750's and up to 1978 models.

Yamatoya Motor Sports is now going to help me with getting a 45 tooth
alloy sprocket #530 for the rear wheel. That will give me 2.6:1 ratio.

They answer the phone and call you back too!!!

 

DISCLAIMER: I may use capital letters to emphasize the importance of what I am talking about.

I am not mad at you or being condescending.I continued with the scraping of the grease and the paint on the engine today.
I did get a couple fun things finished.
I installed the valve cover that I cleaned and painted.
I also got new screws for the cover.

I used carburator paint on it because it has a sand cast look.It is fuel resistant and temp resistant up to 250º.

I removed the alternator cover which was damaged and had fiberglass or epoxy sloped on it to keep it from leaking.

I discovered the MESS that you see.
A motorcycle engine cannot have this kind of gasket sealer on it unless you want some real trouble. A little piece of that junk can break off inside the case and get in the oil pick up screen or a rod bearing oil journal anything!
IT told me that the person working on it did not have any motorcycle mechanical training. And they must not be able or want to read a repair manual.
I replaced the case with a brand new OEM case.
I also replaced the gasket.
You put GASKACINCH on one side (case side) and on the other side a light coat of oil or Vasaline so if you have to remove the case the gasket will not get torn up.

This was the next stop -the points cover.
It had blue silicone mess all over it too.
Even the condensation drain hole at the bottom of the cover was plugged up with fiberglass.

I will be cleaning all of this up also.
The points cover from the factory usually had a cork casket and it was glued to the points cover and you could just remove two screws and it would fall into your hand.

I had to pry this one off. A mess.

 

Those valve covers look GREAT!!! In that picture it looks as though the head is black, did you paint the head and the fins black?

 

Thanks, who_iz_phil, and you are right, the cylinder head and cylinders had been painted
black so I will stay with the black. If I was rebuilding the engine I would get the
cylinder and head hot tanked. Those two parts are very difficult to clean when they are mounted on the engine..

 

Great job hs been done Donal.
Keep continue with your update... we are waiting for your day by day creation...

 

You keeping the points or going digital ignition?

 

I will switch to electronic ignition.
I was a mechanic during the "points" days and know all about the drawbacks.
They do work though. But they wear down with in three months and need replacement.
The dwell keeps changing as they wear.

 

You're going to want to upgrade that fuse box. Those heat up and melt fuses all the time. I converted my 1976 CB750F to blade type fuses, electronic ignition and upgraded the coils; I've never had a charging problem or electrical issue since. I'll see if I can find the replacement fuse box i used if you're interested.

Also If i remember correctly all engines on the CB's after 1977 were painted black from the factory. the 1976 model was the last with the silver engine.

 

If I could ask, how did you find Yamatoya Motorsports?

 

Darn it!! I just bought a brand new OEM Honda fuse box for a 1976 CB750.
Is that a good fuse box?
They do not have wiring harnesses for the 1978 model like mine so I just decided to
wire the bike as a 1976 and skip the clutch switch.

Thanks for the info too!

 

Stepping back a little here is the engine so far.
All cleaned to bare aluminum and painted.
Cam chain slack adjusted.
Valves adjusted.
Carbs cleaned and waiting.
New alternator cover and new polished left side case.
Clutch replacement next ,just waiting for the tool for the nut.
And new spark plugs.
And the scary part a compression check. I say scary because if the compression is too low or uneven I will have to rebuild the top end and that is at least $500.00!
The odometer showed 28,000 miles ,not that much for a CB750.

 

OK, this is the fuse block I used on the CB. I tried to go the OEM route as well and it melted also. They are notorious for doing this.

FUSE BLOCK LINK

The terminals are on the back and the cover makes a nice waterproof cover.
I have a wiring diagram around here some where for the 76...
Oh, here's mine...