building an '81 cb750c bobber

[bobbabouskie]

Hey guys, I purchased this 81 cb750 for 600 dollars in November.



after I made sure it ran and everything I started to strip her down.



I decided it needed some modernization



I purchased forks off a cbr600rr and a bearing kit from all balls racing. with a bit of persuasion we got the steering stem from the 600rr to work with the head tube, it was a bit shorter so we (My father is helping a bit) pressed it out milled it down to fit from the top and so the bearing would press on, then we welded a nut in the bottom and used a bolt washer and loctite to clean the bottom side up.



now that the front end is pretty much figured out (aside from lights and possible riser clip ons ,size yet to be determine) I decided it was time to go after the rear end, it is going to be a rigid frame, so I cut off the subframe and shaved the mounts.



I bought a 94 cbr 600 f2 for 300 dollars from a guy on craigslist. This gave me the swingarm I will use, the motor will be used in a shifter kart at a later time. so after getting the subframe out of the way it was time to mock the swinger up.



Seeing as I am making it a rigid we took the bearings out of the swinger and had our local machinist shop turn us out some steel bushings with 5/8 ID for the axle. then I TIG'ed them into the swinger. using some washers we had laying around we got the swinger spaced so the tire is in the center. It looked as though the sprockets lined up like it was meant to be! all I had to do was invert the now new rear sprocket!



And that is as far as I have made it to date. waiting on my seat which I will be using an airbag for suspension on. picking up a peanut tank for it this Friday and getting a front tire at the same time so I can set her down get my ride height set and weld some braces on the soon to be part of the frame/swingarm. then to tackle wiring. Let me know what you think!!

[shinyribs]

Cool looking build man!

Di you happen to have any pics of what you did to the steering stem? I can't quite figure out what you did. And my curiosity is piqued now.

[bobbabouskie]

unfortunately this is the only pic I have of it. but if you've ever seen a normal one you could probably see the difference. the stem pressed in from the bottom and only pressed in so far due to a ridge. but it was about a half inch too short. so we pressed it out and filed it down and used emory cloth to get it the right size to press in far enough and so the bearing and race would sit flush with the triple. and since there was now less material holding it in we welded a nut in as the picture shows. then to clean up the look we JB welded a nut in the bottom and used Loctite to hold the bolt and washer to clean the look up. not that many people would know to look there but it was for my own mind. hope you can picture what we did with that.

[bobbabouskie]

after ive been waiting patiently for a few weeks I have received some parts, on Friday im also picking up my front rim and tire and my jets!

[Al-X]

How come you're making a rigid bob with modern sport bike suspension, minus the monoshock, that is???  I mean, going by the pics, it appears to be a cafe bike with modern suspension.

[shinyribs]

Cool front suspension + Cool rear suspension = Cool bike

I have a hardtail BSA at the house I'm thinking about running some USD's on. That's the answer I give them. lol

[bobbabouskie]

i wanted the swingarm from the cbr600f2 because it was easier to use the wheel it lined up perfectly with the sprockets, instead of having the cush drive milled down and using an offset front sprocket with the old swingarm which weighed a ton compared to this one. i also like the look of old meets new. i like to think of it like this olds cool news cool (old school new school)

[Hellbilly429]

Sweet unique ideas man, I like it, looking forward to seeing more

[bobbabouskie]

got a couple updates here!

so I decided to use a peanut tank cause I like the look and don't necessarily plan on going cross country with the bike. well checking the fitment on it showed the petcock was right on the frame so what do you do? obviously cut the frame and turn it in right?





after I got that all squared away I bought some inch and a 1/4 wide by 1/4 inch thick tube for my hardtail, figured that would be strong enough seeing as I only weigh 180 on a bad day.



and just today I got my tank mounted and started to figure out mounting my seat.



not too shabby if I do say so myself.
ive been kinda going back and forth on paint scheme, I think for this year im just going to paint it all black and next year seeing as it is a Honda I am going to go with a repsol paint scheme!

couple questions what batteries do you use? I would like to run a somewhat smaller one seeing as all I will have to power is my headlight and tail light, how do you run an analog oil pressure gauge, and what is a good speedometer? I cant use the stock one seeing as it has been radically regeared for torque! do I run an expensive ass gps one? or can I run one off of my tach?? thanks Andrew.

[TOOLS1]

I would have just relocated the petcock in the gastank, but narrowing the frame rails sure cleans up the top of the bike. As for the speedometer, since it runs off the front wheel, changing the gearing will nor affect it.
TOOLS

[bobbabouskie]

the forks I put on it and the wheel in the front is off an '05 cbr 600rr and the speedo is ran off the tranny on those bikes I believe, that is how my 02gsxr 750 is at least. otherwise I would be all for running it that way.

[bobbabouskie]

I realized today I put the wrong pic on for the tank mount and seat mock up!

Here it actually is!

[bobbabouskie]

got my subframe made for my seat mount and snapped a few pics!









and I threw on my carbs and put the pods on as well, I know a lot of people hate on the carbs on the dohc with the CV carbs but its all in good taste I belive, can always buy different carbs later right??

[TOOLS1]

That's coming together nicely. I like the air ride seat.
TOOLS

[shinyribs]

A few guys here (and other places) have had good success with pods on CV's. I guess there are less success stories than there are horror stories,but it is doable.

Bike's looking pretty cool man. Keep it up!

[hellsford]

Any chance you still have that front fairing? I'm currently looking for some touring gear lol

[bobbabouskie]

I definitely still have it with the radio still in it. I'm not gonna lie it isn't in perfect condition though. 

Sent from my iPhone

On Apr 8, 2014, at 2:35 AM, "hellsford [via Honda CB750'S]" <[hidden email]> wrote:

Any chance you still have that front fairing? I'm currently looking for some touring gear lol

---

If you reply to this email, your message will be added to the discussion below:

http://honda-cb750-s.456789.n3.nabble.com/building-an-81-cb750c-bobber-tp4048848p4049921.html

To unsubscribe from building an '81 cb750c bobber, click here.
NAML

[hellsford]

I wouldn't mind too much unless it's badly damaged. Think you would be willing to sell it?

[bobbabouskie]

i certainly would be willing to sell it, i'll snap a few pics when I get a moment and put em on here.

Anybody have any ideas on oil pressure gauge? or does everyone just run the oil light?

still haven't decided about a speedo yet, ive seen the type with the piece you put on the wheel and it reads it but I have one on my quad and after 50 it peters out, do I just go ahead and spend an arm and a leg on a gps one?

another thing I have a question about is throttles, is there one I could buy for this kind of carb that doesn't look big and bulky like the stock one? I really want this bike to be minimal looking as possible, only headlight only tail light, wiring ran through the frame tubes etc.

[bobbabouskie]

Here's a couple pics. 

Hope the pics work I'm just doing this from email!
Sent from my iPhone

On Apr 8, 2014, at 10:39 PM, "hellsford [via Honda CB750'S]" <[hidden email]> wrote:

I wouldn't mind too much unless it's badly damaged. Think you would be willing to sell it?

---

If you reply to this email, your message will be added to the discussion below:

http://honda-cb750-s.456789.n3.nabble.com/building-an-81-cb750c-bobber-tp4048848p4049952.html

To unsubscribe from building an '81 cb750c bobber, click here.
NAML