Topic: CB750K7 cafe racer build.

[stou]

Thanks algophobe! I know I should have taken more pictures to better document my build, but I often forgot to take pictures, too much concentrate on my work.

About the K7 gas cap, I can't really tell. I rode the bike only once before I modified the gas tank, and it was only to go to the inspection and there was only a small amount of gas in it. Right after that I started to work on the bike. Now with the flush mount cap, it is well sealed and the vent is really well made in the cap. The only way to have an overflow is if I filled the tank up to the cap. Since I know it, I will take care not to filled it too much when I'll do the fill up.

[physician]

Nice build. Wich 826 kit is that?
I have troubles finding someone to bore out for 836... they all say its too thin... even while i tell them its common they dont want...

[stou]

It's a Wiseco kit. I bought this kit because the machine shop who did the work on the engine, already have one in stock. I had a really good price for the kit. It's a bit more expensive to have it bore for the 836 because they have more pass to do to remove all the material. They did a nice job on the cylinder and the head.

This is the shop who did the work: http://jprecision.com/

Wiseco 836 kit: $593 CDN (very very good price!)
Bore & hone : $430 CDN
Work on the head: $426 CDN (new guide, work on the seat and head surface)

[physician]

It had quickly! But thats a good price for a good job! Cheaper than doing it twice they say..

[stou]

Unfortunately, I don't have pictures for many steps. But those steps where relatively simple regular jobs on motorcycles. The next important thing to do was the electric work. Everything is connected in the headlight. In order to do that, I needed to install the headlight and I don't had any mounting brackets that where working whit the CB headlight and the GSXR forks. So I decided to machined one.

I started with a 3" piece of aluminium and machined it to the right inside and outside diameter size.







After that I did the parts that hold the headlight



And powder coated them in satin black

[calj737]

You started with 3” material to turn them down to maybe 2”? That’s a lot of wasted material  Would have been easier and cheaper to use some tubing with a thick wall and turn just a bit off. Probably Schedule 40 or 80 6061 would have worked and for 6” you’d easily get both sides out. About $10 of material versus a blank worth $60...

[754]

Thru Midwest Metals 6 inches of 3 inch is 23.08
 I suspect my local supplier is around that  or less.
 Tubing in many places is harder to find, and 1/2 foot of 3 inches tubing is a very small tube order.
 I think tubing cost is  higher per pound than bar stock.
 
 The headlight mounts look really good, do you have a TIG welder Stou ?

[calj737]

Tubing in many places is harder to find, and 1/2 foot of 3 inches tubing is a very small tube order. I think tubing cost is  higher per pound than bar stock.   

Not around here, Frank. I bought 12” of 2” Sched 80 on Thursday for $8. I bought 8’ of 1” .125 wall for $15.

Admittedly, 3” solid may not be $50, but the time to turn it down is surely worth that much!

[stou]

I already had those 3" pieces of alu, so it was cheaper for me to do that. Also I'm not sure I can find those kind of tubing around here. I took the easiest and cheaper solution to do it.

Admittedly, 3” solid may not be $50, but the time to turn it down is surely worth that much!

That's not a problem, I'm retired, so I had plenty of time to do it ;-)


Yes Frank I have a tig welder. But I need more experience on welding aluminium to do very nice weld ;-)

[Godffery]

 Some pretty nifty work you're do'n there Man!

[754]

On my lathe punching the hole is easy, cept my lathe is not wired up now. I have a 20 inch I can use ocassionaly..
 If you have them, or can borrow  one  Rotobroach  thru, 1/2 way from each side.
I got drills that big anyway.
Stou, what lathe are you using ? What size in talistock, M3 ?

[stou]

Some pretty nifty work you're do'n there Man!

Thanks Godffery!

Stou, what lathe are you using ? What size in talistock, M3 ?

I had a very old Southbend, something from 1947! But I replaced if for a French lathe, Precise brand. It'S a 7"x24". I think this one is from the '60, a lot better than the previous Southbend. I'm not sure about the tailstock.

Here's a picture of the old Southbend and the new to me Precise

[754]

 I thought I had seen a South Bend   in your pics.. the  I saw the other one.. hmmm
 The French lathe, looks like lever operated tailstock, very nice for most drilling. Looks like a good machine.
And a very nice collect selection,  are they some oddball type or somthing we use here ?
 So you have a milldril, too, you are set.

 I thimkmi will be using my South Bend soon my 16 inch lathe, needs 3 phase and I got nowhere to set it up.. right at this time. 

[stou]

Yes, the tailstock is lever operated, very usefull. The collets are in mm and very good quality.

I bought the milldril last year at Busybee tools in Ontario. It's a small one but I don't have enough place in my garage for a big old one.  My friend have an old industrial big mill that work on 550V. He paid less than what I paid for my small one but it is so big, he had to rent a lift to move in his garage!

[stou]

To complete the build, I made a small bracket to install a digital multifunction gauge, an Acewell MD052.



I made a fiberglass seat pan from this cardboard to have the seat made by a local guy.


An here's the complete build. The wheels was powder coated black. The paint I did is special. Unfortunately, you can't really see the effect on pictures. I did a solid black base. Then I masked the middle stripes and applied a prismatic pearl black paint. After that, I did a faded silver on the top, and finished it with red pinstripes and my Stou Design logo on the tank.











Next the winter, I'll shop for a 4 into 1 exhaust. I also want to put the front brake oil reservoir lower and maybe replace it with an aluminium black one. I also need to powder coat in black some other parts like the levers and some other smal parts.

[754]

Wow that is nice, i see it as a Bike of the
 Month nomination in the near future...

[stou]

Thanks Frank!

[SOHC4 Cafe Racer Fan]

Nice job, Stou.  Let us know how the stock rotors/GSXR calipers work out together with more miles. 

[stou]

Thanks!, I'll let you know but probably only next year. Here we already had a bit of snow last weekend and there's not much riding days left for this year.

I have a question for you guys. I installed a LED lignt beside the Acewell gauge, and use it for oil pressure. I was always on, so I checked the oil pressure sensor and it was bad. So I bought a new one but the light is always on. I also have a gauge on the side of the engine and it indicate 60 psi on idle and go up when I give some throttle. So the pressure look ok. Is it because it's a LED? Or a bad connection? Or pressure is too low? Is 60 psi on idle is ok? The light is connected to the pressure sensor wire (blue/red) and 12v.

I also have another electric small problem. The high beam blue light is always on. If I remove the headlight, it work but when I connect it, the high beam light is always on even when on the low beam. I'm connected on the blue wire.

[Shtonecb500]

This was a very inspiring build to review with great ideas, thank you for sharing this.

[stou]

Thanks Shtonecb500!

Unfortunatly, I think I have a lubrication problem on my bike. I openned the tappet inspection cover and there's oil but it look like there's not enough. I put lot of money to rebuild the engine. I don't want to seize the cam.

I read a lot about the 750's oil starvation problem and I will need to check many things before I can ride it.
  http://forums.sohc4.net/index.php?topic=163920.0

Anyway, we are supposed to get some snow next week... 

Yesterday we had a very nice trial day, it was the last of the season. So now, I will have plenty of time to look at the oil problem!

[stou]

Yesterday I take the time to remove the valves cover and had a look on the lubrication channels. I found that there was actually a lubrication problem on the left side, cylinder 1 and 2. If you look at the pictures below, you can see that the left side is much less lubricated than the right side.

Left


Right


So I decided to have a look at the oil jets under the cam supports and also at the small channels in the cam supports. I found that the left jet was clogued, probably by a small piece of gasket, and 2 channels has not free flow. So I clean everything with a guitar string and a can of carb cleaner.



The 4 o'rings was brand new, so I reused them and put the cam back. Before the rockers installation, I decide to do a test to be sure the oil was flowing freely from evary places. As you can see in the video, everything was now working fine!



So now I will have peace of mind knowing that the lubrication of the cam is ok! 

[754]

Was your cam ok ? Looks like the rockers got very hot..

[stou]

This camshaft was in the other engine and it is good. When I rebuild the engine, I took some parts in the other engine. Some rockers was very bad and I took those who where looking better. And this camshaft was in better shape than the one in this engine. You are right, the color indicate that they were very hot at some point. Probably with the other camshaft, who has probably seized. But those rocker's surface was in better shape, that's why I took them. Do you think they can be more fragile because they have overheated?

[754]

Just take a real good look at them.  I ruined a few this year and a 9 month old Andrews cam  that pissed me off.,
 I think it was fuel in the oil though, on mine.,

Some Honda rockers seem to have lighter discoloration than those but similar, from the factory.