My frankenturd

V

vbtravisd

Been Around the Block
Hey fellas, I have been a lurker on the forum for a long while. I have owned a few bikes over the years, from an old virago 750 to an FJR1300. But I have always wanted a cafe. I am very big into cars especially 4wds but I love anything with wheels and a motor. I like to build/fab as a hobby... I have a CNC plasma table and a full fab shop out in the garage. My Jeep wrangler was completely custom with dana 60's front and rear, full roll cage etc... So obviously, I like to tinker with shit and i have to have a project to play with. Well, about 2 months ago I found out Im having my first kid! I decided to sell my jeep (but i managed to keep my boat!). My wife knowing that I will drive her nuts without a project to turn a wrench on suggested I find myself a cafe candidate. I dont know a ton about bikes... so I can see myself leaning on you guys for advice if you dont mind helping out a rookie.

So today after work I am going to go take a look at a 79 CB750 frame with a gsxr swingarm, front fork, wheels and brakes. Which was along the lines of what I wanted to do... classic bike with a little updated technology. The frame has a clear title and the guy only wants 200 bucks for it all. Hopefully I can find another 750 engine locally. I've attached a picture the guy sent me. Do you guys think it is a good platform to start with?

I appreciate any advice you guys can give me along the way!
 

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Re: My first build

Back of the frame has been hacked up, Can you weld?
Also, sohc4 750 parts are VERY ESPENSIVE nowadays. Ready to drop some serious cash?
 
Re: My first build

Yep, I can weld... I have a miller 220V mig and my buddy has a tig I can use whenever. I have a small diameter tube bender and the CNC so I figure frame modifications are the easy part.

Do I have to stick with the SOHC motors? Im not opposed to running a different CC engine. I plan on taking my time with this one so I'd rather buy quality parts and do it right then half ass something and it break/fail/kill me.
 
Re: My first build

With enough time and money, any engine can fit anything. But, unless you are into doing possible major frame mods, yeah, you are stuck with sohc cb750 motors.

The cb750 is not the easiest frame and engine to work on, especially when the motor is in the frame. Any, and I mean any, top end work requires the entire engine to be pulled. Head will not come off when engine is installed. Valve adjustment is about the only thing possible when engine is installed.

Also, the cb750 requires an external oil tank.

Not saying 'don't go for it', just saying you should know what you are getting into when you start a project like this.
 
Re: My first build

I hear ya! This is the kind of input and experience I was looking for. I am not against even building a 1 off frame. I am not dead set of the 750cc... so i guess it all depends on what comes up. Frame having a title is kinda nice. There are a ton of bikes for sale around here with no titles.
 
Re: My first build

You might be able to shove, say, a gs550 engine in there. GS750 or larger wont fit. GS550 engine can accept a gs650 top end with a tiny bit of work. Wouldn't bother with a KZ even if it did fit. GPz I would do. DOHC honda wont fit... I dunno what else you could try to fit in there.
 
Re: My first build

You have to remember that sprocket offset was different for all of these bikes. You aren't running a stock rear wheel on that, so offset would be different anyway, but it's something to remember. Dropping in 'any ol' engine' is kinda a big deal, lots going on there, so consider your choices, you'll end up spending 100X as much time fitting the wrong engine. How much is your time worth?
 
Re: My first build

I think that you should pick something far less ambitious for your first build. Start with a complete, running, (or nearly running,) motorcycle. A project of this scale is for an experienced builder.
 
Re: My first build

Well I say buy it. You should be able to get your money back if you find another deal. Build a frankenstein out of it, dont be like everyone else. ;)
 
Re: My first build

Assuming good condition, you can part that for more than $200. Hell you could probably get $200 just for the front wheel/brake setup.

-Deek
 
Re: My first build

You do realize most of this so far has been utter balderdash.
a 79 CB750 is not a SOHC it is the newer DOHC, it does not have a separate oil tank, and parts are not nearly as hard to come by or expensive as it is often over looked by the Cafe crowd in favor of the older more chic SOHC version.
 
Re: My first build

I figure I will be searching the end of the internet for info... but I know that my biggest asset are guys who have been there/done that. Bikes are the next thing I want to learn about and work on. It seems to me that a bike is all in the details and the little things that are easily overlooked (sproket alignment) and are the items that I figure experienced eyes over my shoulder are a must.

Hoosier, yeah, upon looking around... I see that the DOHC engines were 79-83.... "if its on the internet... it must be true!"
 
Re: My first build

looks like an awesome platform to start with. I'll be watching your progress. Good luck fellow bike newb!
 
Re: My first build

SOHC - WTH are we talking about. Isn't that a DOHC frame?

At that price it's not bad, but that's an expensive way to build a bike. I know because I have done it too many times and have another one like it waiting for me to pick it up. All I need are bodywork, controls, pegs, electrics, motor, carbs, exhaust, gauges, tubes, fenders, cables, chain, sprockets, etc

It always adds up to way more than I wanted it to, but it's the equivalent of an installment plan. In this case, it's $200 deposit and 200 a month for 36 months :)

I'm just about to pick up one just like it so I can't tell you not to do it, but think about it and work out a budget (a.k.a. a shopping list). AT least you won't have a large pile of discarded parts to dispose of as you go along. My CB900 came much like that as a basket case and ended up like this
CB900-0001.jpg


Of course the pods were a disaster and I had to find an airbox.
 
Re: My first build

I hear ya! I have built a few projects like this... the last being my jeep. I collected parts for a year before I ever tore into the thing. And like I said, I don't plan on riding this thing anytime soon and especially with a baby on the way... it is more of a walk out back and tinker for an hour or two and back in the house. Steadily researching... reading and collecting parts.

I found a cb750 DOHC motor locally... the guy isn't sure what year it is. What are some of the differences in DOHC motors over the years? I figure probably some different mounting configurations. Any way to lookup serial numbers to identify the model year?
 
Re: My first build

Hoosier Daddy said:
You do realize most of this so far has been utter balderdash.
a 79 CB750 is not a SOHC it is the newer DOHC, it does not have a separate oil tank, and parts are not nearly as hard to come by or expensive as it is often over looked by the Cafe crowd in favor of the older more chic SOHC version.
Click to expand...

Yeah, read straight over the 79 part.

My bad.
 
Re: My first build

So what are some of the frame differences between the SOHC and DOHC motors? What are the preferences to one over the other?
 
Re: My first build

vbtravisd said:
So what are some of the frame differences between the SOHC and DOHC motors? What are the preferences to one over the other?
Click to expand...


Huge differences, engine mounts, shock mounts, neck size for the forks... but yours is already severely modded so it's really up to you.
On a grander scale, imagine trying to put the drivetrain from a 1967 camaro into a 2013. Can it be done? sure.. but sticking with what was OEM is a lot easier.
 
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