Topic: 74 CB750 first build

[Broseph]

Hey all,
I have been rebuilding a 1974 cb750 for the past 6 months. Thought id start a build page for others to see as well as for my reference. I am nothing close to a mechanic. I didn't even have my license when I picked up this bike! But with help from a friend who rebuilds motorcycles and my own research I am determined to create a cafe racer. Here is a photo of the 74 as well as a 75 cb750f the day I picked them up.

[Broseph]

Here are a few photos of the 74 once pulled into the garage where it will be staying until completed. Was so excited to get the build underway, the bike was down to its frame in 2 days, all parts bagged and tagged as well as photos of every part of the bike for future reference.

[Broseph]

First thing I did once the bike was apart was to cut off back frame, weld in hoop, and then create template for seat. originally wanted to go with a traditional cafe hump seat and may still make one but had created this seat for the time being. Traced template of seat onto wood, cut out shape, then took it to my seamstress (mom) who made the seat cover for me. I used two layers of 1" thick foam for padding. also tore down the engine.

[Broseph]

While tearing down the engine I had found a few problems. Believe the last owner had left this bike outside so there were a lot seized and rusted parts including piston cylinder. used wooden dowel and hammer to knock piston out of cylinder.

[Broseph]

Found chipped area right under points section on crank case which would let in dirt and water while riding. My only options were to try and fix the hole or swap the crank case from the F to the K. everything was taken out of crank case and engine body was painted.

[Broseph]

once paint was dried and clear coated it was time to put everything back in. While trying to install the shifter I broke the stud that holds the mechanism on. Thank god I had the cb750f and the stud was same size. Was very worried about what parts were interchangeable between the F and K.

[SOHC4 Cafe Racer Fan]

I must admit that completely tearing down a bike and cutting the frame on a first rebuild is ballsy.  I assume that since you "committed" you have a solid plan of what you are going to do.  If you can, please let us know, since that can inform some of the advice we can provide.  In particular, frame mods, suspension, engine mods.

Good luck with your build.  In the interim, try to get some seat time so you will be ready to ride your 750 before it's finished.

[Broseph]

Thanks Racer Fan,
I don't think I could of done it without having a friend, i guess you could call him my motorcycle mentor, who has helped me along the way. At the moment the bike is mostly together, just waiting for rebuild parts for the petcock as it leaks and fixing a carb that has been pouring gas. After draining the tank yesterday, there was enough gas in the float bowls that i could start it up. Here is a recent picture of her. Thanks

[Broseph]

Painted the rest of the engine and sanded down the fins. Reinstalled engine components. Was wanting to put a big bore kit in the bike but where this will be my first bike, and a kit is expensive i decided against it.
http://i878.photobucket.com/albums/ab342/T-RITS/IMG_1204.jpg

Got new gaskets, sprockets, o-rings and piston rings. Cam shaft was worn so I swapped it out with the better looking one from the donor bike. Also got new full engine bolt kit. There was no way i was putting the rusty bolts back into the engine!

[Broseph]

Now that the engine was done, time to move on to frame, swing arm, shocks and rims to make this thing a roller. Rims were pretty pitted so I bead blasted and painted the rims black. Got new spokes and laced them up. Dropped them off at a local bike shop to let the professionals true the rims and install rubber. Drum brake pad looked almost brand new so i was able to escape some cost there. Frame was detabbed and painted. Purchased new fork tubes because the ones on the bike were rusted out right where it would pass the seal. Front forks were rebuilt with progressive springs. New rear springs seem pretty stiff while sitting on it but will not know how they really act until on the road. Swing arm got new bearings and dust seals.

[Broseph]

engine was put in to the frame and put the tank and side covers on her to get an idea of what she will look like. Hope no one minds that I refer to my bike as her/she lol. I purchased fork boots with not knowing how I was going to keep the top opening sealed and stop it from just bouncing around. My friend machined two round donuts that slide over the fork tube. these donuts have a slice taken out of them so that a bolt can go through sideways and clamp them tight against the fork tube. They have a divot on them so that the inside lip of fork boots would slide right in. Worked out really well. The handle bars I had purchased were not long enough between the bends so they were cut in the middle with a inch and half section welded in. The previous owner had welded on a unicorn style piece on to front of triple tree which I cut off to make room for mini gauges. The bike at this moment looked very high in the front end so I slid the fork tubes about an inch through top of triple tree.

[Broseph]

Next step I was to tackle the wiring. The old wiring harness was very brittle and worn out so I purchased a new wiring harness. I rebuild the old handle bar switches since some wiring had disconnected from the switches. I installed the switches and got everything connected to a battery to test current. The switches were not grounding through the handle bar switches due to painting the handle bars. I sanded down the handlebars, replaced switches and painted around switches. I also installed bar end turn signals so I drilled out a hole in each side of the handle bar to run the wiring. Then rubber mounted my mini gauges. I also installed an led integrated tail light. Due to clearance issues of the back wheel I wanted to place it right behind the seat. I made a metal bracket that bolts to the underside of the seat. My friend suggested that I wrap the bracket with the same material I had the seat made with and am very happy how it turned out. I loved the look of side mounted license plates so I took a metal lock box and cut out the shape, leaving two side walls for mounting to rear shock lower bolt. Purchased license plate bolt led lights to hold and light my license plate. It took me for ever to find out how to route the wires. I ended up zip tying them to the bottom of the swing arm.

[Broseph]

Here are some photos of the lights

[Broseph]

one of the last things for electrical I did was install an electrical ignition which I'm sure ill be very happy with once I get the bike going. Had an issue with blowing fuses when turning the kill switch. To find out the "e" clip that holds the switch on was turning with switch and was cutting into the wires causing power to flow when switch was off. "e" clip was pushed around switch so that opening was facing wires.
I pulled a favor through someone I knew to get the carbs cleaned and put back together by a professional. They came back in pieces. Two out of four carbs and the inlet where the main jet goes broken off. Not happy. So I purchased a box of extra crabs from a guy to replace the two broken ones. Couldn't help but to sit an extra tank I have on the bike to see what it looks like before the parts come back from paint.

[Broseph]

Got the tank and side covers back from painter. Installed petcock and ran the lines. Petcock leaked from contact area between petcock and tank. Have ordered new seals. Carb #4 poured gas out of the pod filter (don't have the air box). There was enough gas left in the float bowls for me to start the bike up for a few minutes. It was super loud since i did not have a muffler on. I still have a few things left to do. My gauges have different back lighting, one being an led, and would like both to be the same. also trying to figure out an exhaust. I had cut a baffle out of an exhaust and might attempt to create and insert for the 4-1 exhaust. Kind of like the discrete look of it being hidden under the bike. Any ideas would be appreciated.

[Broseph]

Here are some photos of the bike so far

[Broseph]

A couple pictures I took tonight after putting on tank badges. Have the brake hose tied up while caliper arm is off to figure out brake issues.