Author Topic: My 78 750 build (Read 5220 times)

67camaro · « **on:** April 26, 2015, 05:21:16 AM »

I just signed up here andI'm copying this from another forum I belong to. Bought a this cb750 a couple months back from a friend on the cheap. Pretty rough shape, didn't run, pipes were rotted out, and the front caliper was frozen. Got the itch to start on it the other day. Got it running and started taking stuff apart. This is the bike the day I brought it home.

I had a gsxr 750 front end and swing arm that I was going to put on it but just wasnt feeling the big swing arm. I then found a set of roadking wheels on craiglist. I had the front hub narrowed to fit the gsxr forks and the rotors drilled to fit the roadking wheel.

I had a gs550 swing arm and a set of covered shocks laying around so I decided to try them. I bought a set of fatboy tanks and a set of shinkos today. Threw everything together quick to see how it sits. I think I'm gonna lower the forks more and then cut the frame up. I plan on cutting out the triple backbone and dipping the seat rails to start.

I got the right bearings for the front end and had the stem machined to fit right. I shortened the fork internals to lower the front end 11/2" and put in new fork seals. Got bearings to make the rear wheel work with the suzuki axle. I made spacers and a caliper hanger to run an sv650 front caliper on the rear. Still need to make some sort of anchor. Found out I need a 1/4" spacer for the rear sprocket to line up. So I ordered a spacer, chain, and front sprocket. I cut up a virago tank I had and just tacked it together. I think I'm gonna end up using it.

I put it up on the lift and started cutting. I cut out the backbone and seat rails. I bent up some tube to loop the vertical rails in front of the seat. I turned some slugs before work today to tie the new tubing to the old frame tubing. Tonight I cut up a piece for the backbone and fit the pieces I bent for the loop. Next up is the seat rails and the new shock mounts.

I made the shock mounts and got the seat rails tacked on.

Restoration Fan · « **Reply #1 on:** April 26, 2015, 05:25:59 AM »

First of all, welcome. Looks like you're biting off a big chew but you certainly seem to know what you're doing.

What's your vision for the bike? It appears you're going for a fatboy styled Harley-look-alike?

Stev-o · « **Reply #2 on:** April 26, 2015, 06:07:42 AM »

Welcome from Texas. That was quite a first post! Looks like you have some serious build skills, what else have you built?

67camaro · « **Reply #3 on:** April 26, 2015, 09:01:37 AM »

Thanks guys. The bike is almost done but my computer was acting up this morning so I have to finish adding progress and pics to the thread. I've built a few bikes in the past but this is my first cb.
07 sv650

81 gs650

80 gs550

86 virago 1100

67camaro · « **Reply #4 on:** April 26, 2015, 09:04:42 AM »

86 virago 1100

67camaro · « **Reply #5 on:** April 26, 2015, 09:38:54 AM »

Now back to the cb750.

I made new shock bushings out of some Delrin.

I wanted to finish welding the frame before I went any further. I added some gussets at the rear shock mounts and where the seat rails meet the back bone. Also added a small piece at the pinch weld behind the neck to make it look more finished and welded on a small piece for a new steering stop. It's back to being a roller again now to make an oil tank and finish the gas tank. Then onto the seat and rear fender.

I started fitting the tank and trying to decide which fender to use so I can make the seat. I have a piece of an old ford spare tire ring sitting on it right now but I have a sportster fender I'm going to cut up and try tomorrow. Also have a sportster king tank that I might narrow and use instead of the virago tank.

Got the rear fender mounted. 3/8" rod and some bungs I made fro sch 120 pipe.

Then I made the tunnel for the gas tank

This was the first time I pushed it outside

I started making an oil tank to fit the new frame.

I finished the tank by welding in the filler and the bung for the petcock.

Stev-o · « **Reply #6 on:** April 26, 2015, 09:54:10 AM »

Nice. I see the Camaro in there too. Pic? I had a '68 Firebird Convert a few years back.

brandEn · « **Reply #7 on:** April 26, 2015, 10:06:13 AM »

What did I just stumble into?! WOW, what a cool bike. You have some good fabrication skills! Are you doing all that metal work in your garage or do you have access to some great tooling? That GS550 is awesome.

SOHC4 Cafe Racer Fan · « **Reply #8 on:** April 26, 2015, 11:53:56 AM »

Those are some clean, tight welds. Obviously, you have some great fab skills.

Aside from wanting a single upper rail (making tank fitment easier), was there any other reason to replace that portion of the frame? What is the overall design? Bobber?

martin99 · « **Reply #9 on:** April 26, 2015, 12:14:21 PM »

Love threads like this. If I had a quarter of your skills I'd be a happy boy

Looks like fast work. How long in real time to get where you are now?

67camaro · « **Reply #10 on:** April 26, 2015, 12:25:39 PM »

I have a slip roll and a finger break at work but 99% of it was done in my basement shop.

I mounted the coils under the down tube to fit in the tunnel of the tank.

Made a battery box for the tiny battery. I mounted it where the center stand used to mount on the frame. Turned some 3/4 shaft down to fit and welded that to the sides of the battery box.

Made the tail light/plate mount.

I had not been working on the bike much do to getting my lathe working that I bought a few years ago and my vacation. I did manage to get the choke cable mounted in the steering stem today. I turned a piece of delrin down so that it would press into the stem. I drilled and tapped the center of it so that the choke cable would thread into it. Then I turned down the choke cable housing and threaded it to match.

67camaro · « **Reply #11 on:** April 26, 2015, 01:11:14 PM »

Quote from: CB750 Cafe Racer Fan on April 26, 2015, 11:53:56 AM

Those are some clean, tight welds. Obviously, you have some great fab skills.

Aside from wanting a single upper rail (making tank fitment easier), was there any other reason to replace that portion of the frame? What is the overall design? Bobber?

No reason other than tank fitment and clean lines to go with the back half of the frame. I guess you could call it a bobber. I just build what I like to look at.

67camaro · « **Reply #12 on:** April 26, 2015, 01:12:55 PM »

Quote from: martin99 on April 26, 2015, 12:14:21 PM

Love threads like this. If I had a quarter of your skills I'd be a happy boy

Looks like fast work. How long in real time to get where you are now?

I've been working on it on and off for a little over 2 years. If I would of stayed on it steady I could of been done long ago.

67camaro · « **Reply #13 on:** April 26, 2015, 01:56:48 PM »

I then moved onto the exhaust. I used a 750 super sport header and a Cone Engineering muffler and made the pipe in between.

I cut up the stock kick stand and welded a new foot on the end.

Mounted the speedo on the motor.

I pushed it outside one last time before I took it apart to finish the welding and paint the frame.

I didn't like the first set of shock mounts I made for the frame so I made another set.

I was going to use a hidden toggle switch for the ignition switch but I couldn't decide what to do with the spot on the top triple where the gsxr switch was mounted. I bought a universal ignition switch and this is what I came up with.

I made the seat and had it covered by a local guy.

In the last few weeks I painted almost every part of the bike and started assembling it. I started on the wiring so it shouldn't be long now.

brandEn · « **Reply #14 on:** April 26, 2015, 02:40:14 PM »

This bike is really turning out great. Did you do any engine work?

67camaro · « **Reply #15 on:** April 26, 2015, 03:03:50 PM »

No the motor is stock for now. After I get it on the road I plan on at least a cam and maybe an 836 kit or something like that.

SOHC4 Cafe Racer Fan · « **Reply #16 on:** April 26, 2015, 08:21:47 PM »

Ef me! The welds on the exhaust pipe are spectacular!!

GaryCrox · « **Reply #17 on:** April 26, 2015, 10:28:08 PM »

Great post, I am busy with an oil tank design for my cb 750, what is the capacity of your oil tank ? I live in a warm climate do u think I should increase the capacity?

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P.abrera · « **Reply #18 on:** April 27, 2015, 07:50:18 AM »

New guy to the scene, but i can tell when the work is good...and this is more than good. So inspired with the work here. Really nicely done..

67camaro · « **Reply #19 on:** April 27, 2015, 06:00:22 PM »

Quote from: GaryCrox on April 26, 2015, 10:28:08 PM

Great post, I am busy with an oil tank design for my cb 750, what is the capacity of your oil tank ? I live in a warm climate do u think I should increase the capacity?

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My tank holds about 1/4 quart less than stock. In your case I would think more is better.

Retro Rocket · « **Reply #20 on:** April 27, 2015, 06:35:44 PM »

Quote from: GaryCrox on April 26, 2015, 10:28:08 PM

Great post, I am busy with an oil tank design for my cb 750, what is the capacity of your oil tank ? I live in a warm climate do u think I should increase the capacity?

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Just measure the volume of the stock tank, its plenty, if you have an over bored motor with cam and so on, install an oil cooler... I live in a very hot climate...

GaryCrox · « **Reply #21 on:** April 28, 2015, 09:45:38 AM »

Thanks for the advice, will do as you suggest.

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knowsnothing · « **Reply #22 on:** April 28, 2015, 11:49:23 AM »

Damn man, great work!

67camaro · « **Reply #23 on:** May 10, 2015, 06:29:39 AM »

I got the bike running this week. I still have to fix some issues with the carbs but at least it runs. Yesterday I made a button out of delrin for the seat hold down and I mounted the speedo pick up. I had to make a new magnet holder and a bracket to mount the pick up. The magnet holder that came with the speedo did not fit in the rotor buttons so I turned one out of delrin.

SOHC4 Cafe Racer Fan · « **Reply #24 on:** May 10, 2015, 08:11:36 AM »

Nice work. That's a big piece of delving stock in your lathe.

67camaro · « **Reply #25 on:** May 10, 2015, 06:36:26 PM »

I buy the delrin from McMaster-Carr, it's pretty cheap. I sanded and cleared the tank yesterday. Today I put the tank, seat, and fender on and pushed it outside. I'm hoping to take it for a ride this week.

Retro Rocket · « **Reply #26 on:** May 10, 2015, 06:57:53 PM »

While i'm no fan of the tires on this bike, i really like the way it turned out, good skills mate...

Restoration Fan · « **Reply #27 on:** May 10, 2015, 08:34:46 PM »

Nice result for the bike. There's not a lot of clearance between the rear fender and the tire. Better hope you don't hit a bump that compresses the shocks or you're going to be rubbing that tire. Possibly enough to stop the wheel?

SOHC4 Cafe Racer Fan · « **Reply #28 on:** May 10, 2015, 08:50:04 PM »

Those are some truly impressive fabrication skills. I bet those rear shocks are pretty stiff given the small amount of travel and the clearance to the rear fender -- a flexi-rigid.

P.abrera · « **Reply #29 on:** May 11, 2015, 01:22:43 AM »

+1 really enjoying the fabrication work that you put in.

67camaro · « **Reply #30 on:** May 11, 2015, 01:21:02 PM »

Yeah the rear shocks are very stiff. Barely any movement at all. The bike is pretty much a rigid.

67camaro · « **Reply #31 on:** April 09, 2016, 04:55:23 PM »

I haven't updated this in a long time. I didn't do much to the bike over the winter but I did make a new set of foot pegs and handlebars. The bike also got 2nd place in the Martin Moto modern classics show a few weeks back. Now I'm just waiting for warmer weather to get out riding.

Stev-o · « **Reply #32 on:** April 10, 2016, 06:36:05 AM »

Congrats!

underdog · « **Reply #33 on:** April 10, 2016, 10:31:53 AM »

Wow, that turned out really nice!!!

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Author Topic: My 78 750 build (Read 5220 times)