79' DOHC CB750 Canadian Build

[Nust]

Greetings guys and gals,

I'm still a pretty new member to the forum but thought I'd start a thread for my current project and share my work and probably ask a few questions along the way.

So I picked up this 79 cb750 sitting just as you see it here in the truck.

This past weekend I started working on it at the shop. Stripped everything I didn't need, chopped off and ground flat most of the tabs (still got a few to do). The plan is to re-wire the bike including the install of an m-unit blue. I swapped a 17" spoked wheel onto the back to replace the comstar wheel it had. Next I'll chop up the subframe to add a hoop and flatten it out. My plan will be to raise the rear some to accommodate that and lower the front to get level. The rest of the build includes a new pipe for the 4-1 header, clip ons, new controls, round headlight, new gauges, rebuilt forks with progressive or racetech springs and new shocks on the back. Lithium battery to be hidden and then a motor rebuild. Treat the whole thing to powder and paint and I havnt decided on a style of rubber yet.

Any input or thoughts are always appreciated and considered but not always followed.

 

[Nust]

Got some more work done on the project today. Tore down and removed the engine out of the parts bike finally also. If you need some stock cb750 parts from a 79 just msg me.

As for the project I sliced up the subframe and tacked a piece of tube on to mock up the levelled look and check for issues, fit etc. Seems to work so now I'll bend up the hoop and weld it in place of that piece I test fit.

Getting the motor out of the parts bike was more work then expected. Makes me think maybe I'll just reassemble the rebuilt engine inside the frame one piece at a time instead of trying to avoid scratching anything installing it as one piece. Anyone got a suggestion on that?

 

[TheCoffeeGuy]

Where in Canada? I am just outside Toronto.

 

[coyote13]

Not sure on the DOHC but on the SOHC CB750 the head is not able to be removed or replaced with the engine in frame, you may want to check clearances before you start assembling the engine in frame

 

[Nust]

Coyote thanks for the info, I'll double check that but I'm sure I'll be putting the motor into a bare frame when it's all been powder coated.

Coffee guy I'm in Sudbury about 4 hours north of Toronto

Was gonna fab and install a hoop today but rushed a bit and kinked my tube when I was bending it. Sadly was the last of my tube so I'll have to get more tomorrow and get that done.

 

[pacomotorstuff]

Ah, another Canuck.
Nice project - the frame mod is a good one.
I, too am just outside of Toronto (northwest of it) - but don't have a hangar to work on my bikes in LOL.
Pop me an email when you're getting ready to look at some bodywork - we've been supplying folks with our made-in-Canada fiberglass products for over 15 years...
Keep posting your progress.
Pat.
Pacomotorstuff
P.S. nice Cub, must really dance with the O-235 on the firewall.

 

[Nust]

Well I got back to work on the hoop today and after a couple kinked attempts at the bend I got it. So as you can see I still have to cut its length as it's way to long and still needs a 20 degree upward bend. Either later tonight or tomorrow I'll take care of that and weld it all up.

Paco, thanks for the advice, I'll certainly reach out once it's time for bodywork but it's mostly just going to be the tank. As for the cub I can't honestly speak to it. Belongs to the father in law. I've been up once and given my fear of flying it certainly seems to move. Luckily his interests extend to bikes and under his extensive tutiledge We've done some cool work. As for the flying and the work on that thing I stay well clear lol.

I've also attached the last project we finished in the spring.

 

[teazer]

That hoop looks like it's the right length, but would look better with a slight uptilt at the rear.

 

[Nust]

Hey Teazer, plan is to put a 20degree upslope on it. Its gotta loose at least 3-4" to be to my taste. If I was keeping a café bump on the back then maybe it would be fine. Just gonna finish with an upslope and a thin seat to go with a brat style look in the back.

I appreciate the interest guys feel free to chime in with suggestions or ask some questions.

 

[Nust]

Well I got a little more time in on the cb today, bent the hoop up on a 20 degree slope, trimmed it to length and made some slugs to weld it up. I'm gonna just clean up its portion around the shock mounts before I finish weld it.

I also built a small box for the bikes electrics in the form of an M-unit blue and tucked that away under the tank just above the carbs. Not sure how welll you can see that in the pic.

Tomorrow I'll finish weld the hoop and build a seat pan.

 

[CarbsAndCylinders]

I'm subscribed

 

[Nust]

Not much to update on the 79 as some repairwork got done to then MK1 in the way of a new R/R after the last one died and left me on the side of the road. I did finalize the m-unit housing and will wait to weld it into place once I’ve mocked up the electrical to determine The size of the holes it will need cut in it. Also I welded the tail section up and I did get a chance to chop up the front fender. To be honest I’m having an internal debate about the length, part of me wants it shorter and the other part debates even having it if it is much shorter. Regardless if it stays it won’t be staying chrome. Anyways let me know what you guys think about it’s length.

 

[cxman]

check your rotor resistance if its out of spec it will over heat the rr

 

[Nust]

Wasn't on the Cb was on my GSXR build, relocated the R/R to a slightly questionable area for heat and proved to be rightly worried, overheated the unit and killed it. Had to relocate it to an area that's a little more exposed then I would like but will guarantee it stays plenty cool. I understand the R/R on these CB's need to be swapped out for newer models to accommodate newer Lithium Ion batteries, can anyone attest to that? Also has anyone ever run an 8 cell anti grav on a 750 with elect start without any issue?

 

[TheCoffeeGuy]

I run a Shorai 8 cell on my 1980 GS850 with no issues. 4 years going now.

 

[Integra99]

Looks cool.. maybe its the photo but the seat and hoop look quite long.. are you planning to run a racer hump of a flat seat.

Nice colour on the GSXR, is that Audi Nardo Grey? I want to do my CB400f in a similar colour!

 

[cxman]

i dont know of a mofset you can use on the dohc

the reg/rectifier on a dohc and cb650 sohc also control the electromagnetic rotor

 

[Nust]

The grey colour is actually a dodge colour called “anvil grey” I really like it too and get a lot of questions about it.

Good to know about the shoerai batter I’ll likely give the antigravity 8 cell a shot, the smaller the better. I’ll be fabricating a box for it this weekend along with a seat pan and then it’s on to foot controls.

The seats about 22” from tank to tip of the hoop, wanted it to sit two without being to tight. The seat will be a flat brat type.

Once again thanks for the interest and info everyone.

 

[Integra99]

I saw a car on Bitchin Rides last night done in Porsche grey (a new colour) looked similar but certainly the route for my CB400f, its in primer at the moment!

Understand with the seat.. I'm in the same position as wish to carry a passenger on this bike.. I've shortened it a little so hopefully she will fit ha ha!

 

[Nust]

That’ll look great in that grey. I gotta make sure my wife fits after removing the tail on the MK1 altogether. Keep up the goodwork. I’ll post some more updates over the weekend as I’ll be working on it again.