Topic: CB750 drag cafe build

[B.O.X.N.I.F.E.]

Man I like a lot of what's going on here, go into as much detail as you want, post lots of pictures. This build is right up my alley.

Thanks man, i plan on updating this regularly.  I checked out your trip link in your sig. Thats awesome wish i could run a trip like that. btw, the second link sends me to an error page, or i just dont know how to use facebook.

I think you have to already be signed in to facebook when you click it. I'm trying to move all those pictures, glad you enjoyed the trip. I'm still watching for those rake pictures!

[Vbled1]

What size tires are you running front and back?

Front and back are both 120/70

[mynameismudd]

looking real good

[lucky]

Hey good for you for following through on this and I agree with everyone else - looks very good! So now I am very curious to know how it handles:

1. In a straight line at speed
2. In corners at say 40-50 mph. I am guessing your steering is going to be all screwed up but thats just a guess? So very curious for some real world feedback. Thanks.

Anyway love the look, very different!

cheers
Andy

why would the steering be "all screwed up" Makes no sense.
Larger wheels shorter wheelbase but more rake. Makes sense to me.

Harley Davidson XR750 won more races than any other motorcycle.
It had two 19 inch wheels and 30º rake. 56.75 inch wheel base.

[the technological J]

wouldnt the increased rake cause greater trail and a larger turning radius? i think the steering should be described as different... but technically the handling would be worse

lucky what was the trial on the xr?

[Vbled1]

Hopefully i will be riding the bike in about a month, need oil tank and a seat, finish rearsets, paint etc.. And i will update on the steering, truthfully too, lol. Also, just a note, i havent shortened the wheel base, initially it looked like about 6 inches longer but with chain on and tensioners set up its probably 4 to 5 inches longer. The bike looked a little too long initially, so i sucked up the rear tire, which i think will especially look better with the seat.

[Bluegreen]

Cool bike man!! Good job on thinking outside the cafe with those wheels . Eagerly awaiting a ride report.

[Vbled1]

Not much of an update, just posting some stuff i was working on over the passed few weeks. Oil tank inspired by some members here, Timdhawk and vtec. Also made an electrical tray. finished the rearsets, (thanks 754, for the wire hanger trick) bent the kickpedal. Cleaning up frame, painting frame and engine in next few days. Engine paint layout inspired by carpys tt special. (Which is going to be an awesome bike.) sidenote, im using carpys frame kit so anyone interested i will post some some pics of the mod.
I was impatient and bought a seat then cut it up as it was way to bulky for my taste, likewise it sat too high. After modifying it, it still doesnt do anything for the bike in my opinion, not exactly sure why but i just dont like it. Working on a new one that is more brat style but not so much. Anyone interested in buying it? PM me
Oil tank almost done, holds about 60oz with about an inch and a half of air.

electrical tray


kick pedal, actually sits nice against the engine.

[Swampotter]

Looks very cool.  Great job.

[Free Booter]

Hey there...been lurkin your thread. I'd been trying to figure out a way to swap out the stock swing arm. I even tried a dresda style, but that didn't work out. After that I borrowed my friend's cb750 custom (basically a DOHC type) and didn't feel like going through the hassle of chopping one up.
I read your post on another thread about your cb650 swing arm and bought one off EBAY for $18. Very cool in that it fit in, but has been a pain now with the drilling. I tried a black oxide steel bit measured at 5/8's" Dia. and it turns out that the thickest part of the pivot axle is 1/32" bigger so it only fit up to the thread...Any suggestions? Maybe you could mail me the bit you used?! LOL...I am kinda stuck now as I can't seem to find a drill bit that won't be too big.

Any suggestions or advise would be great. Link to my build thread is below.

Love the way your bike is turning out...hope mine turns out as nice..Would LOVE to try out the battery box and oil tank idea, but I'm a bit limited on time and tools/resources lately.if I could find a good one that would work or was pre-fabbed that would be awesome...what is the type you used or is it something you made?

[65Ch3v3LL3]

Looking really good.

[033A2]

Noticed you're running the stock front brake caliper, but an aftermarket master cylinder.  Been trying to find a way to improve the front brake on my 73 750K3 and MC is the next logical step.  What type/make are you running?, And, do you notice any considerable difference in braking as a result?

BTW, really like the look you've captured on this build...
K.

[lucky]

wouldnt the increased rake cause greater trail and a larger turning radius? i think the steering should be described as different... but technically the handling would be worse

lucky what was the trial on the xr?

I think it was very normal at about (excuse me)...3.44 inches.

Keep in mind there were different versions of the XR750 frame.
Some had 26º of rake.
Personally I would not want 26º of rake on a one mile track.
I would want at least 30º.
Some of the new Suzuki road racing bikes have as little as 24º of rake!!!
That is why when you see them come up over a hill the front end shakes even WITH dampers. It just helps with the real tight turns.

[Retro Rocket]

Under 3.5 inches of trail would make for a very nervous front end..... Closer to 4 inches would be better....

[Vbled1]

Hey there...been lurkin your thread. I'd been trying to figure out a way to swap out the stock swing arm. I even tried a dresda style, but that didn't work out. After that I borrowed my friend's cb750 custom (basically a DOHC type) and didn't feel like going through the hassle of chopping one up.
I read your post on another thread about your cb650 swing arm and bought one off EBAY for $18. Very cool in that it fit in, but has been a pain now with the drilling. I tried a black oxide steel bit measured at 5/8's" Dia. and it turns out that the thickest part of the pivot axle is 1/32" bigger so it only fit up to the thread...Any suggestions? Maybe you could mail me the bit you used?! LOL...I am kinda stuck now as I can't seem to find a drill bit that won't be too big.

Any suggestions or advise would be great. Link to my build thread is below.

Love the way your bike is turning out...hope mine turns out as nice..Would LOVE to try out the battery box and oil tank idea, but I'm a bit limited on time and tools/resources lately.if I could find a good one that would work or was pre-fabbed that would be awesome...what is the type you used or is it something you made?

Hey sorry i just got around to the thread. Sorry you are having problems with drilling the frame. As best as i can recall, it was 1 or 2 sizes up from stock. This weekend i can tell you what the bit was as i had to borrow the bit from my uncle. And the battery box and oil tank is something i made. sorry im not much help right now will get back to you this weekend.

[Vbled1]

Noticed you're running the stock front brake caliper, but an aftermarket master cylinder.  Been trying to find a way to improve the front brake on my 73 750K3 and MC is the next logical step.  What type/make are you running?, And, do you notice any considerable difference in braking as a result?

BTW, really like the look you've captured on this build...
K.

Sorry i cant tell you what make the aftermarket MC is because i dont know, it was some no name universal type one that was on the bike when i bought it.... so i cant tell you whether it is an improvement. and Thanks.

[killersoundz]

The 21" wheels are SICK! For the record I liked the fender better.

I'm doing similar thing with my bike

[Vbled1]

The 21" wheels are SICK! For the record I liked the fender better.

I'm doing similar thing with my bike

Thanks. Yea i liked the og fender too. Should have left it, it slimmed down the back end a lot and looked really aggressive. Im on to a new seat/tail section now. To be honest idk if i like the new one as much as the og fender. Btw your bikes lookin good. I still need to breakdown and paint.

[Vbled1]

Oil tank/battery box done also.

[killersoundz]

The 21" wheels are SICK! For the record I liked the fender better.

I'm doing similar thing with my bike

Thanks. Yea i liked the og fender too. Should have left it, it slimmed down the back end a lot and looked really aggressive. Im on to a new seat/tail section now. To be honest idk if i like the new one as much as the og fender. Btw your bikes lookin good. I still need to breakdown and paint.

Nah dude that's sick! So cool. I'm inspired for 21" wheels so hard. I want to do my next bike a hardtail with 21" wheels and raked out.         

[Vbled1]

[/quote]


Nah dude that's sick! So cool. I'm inspired for 21" wheels so hard. I want to do my next bike a hardtail with 21" wheels and raked out.         
[/quote]
Thanks man, at this point i just want to ride so i dont care how it look lol.

[Free Booter]

Oil tank/battery box done also.

Hey VBLED...Thought you'd like to know. I managed to get an 82 cb650 rear swingarm on there an it fits great. Only problem is I can't find any chain stops (the little blocks ) for it!? Its like freakin impossible...

My next question is:

What would you charge to make me an oiltank like yours? (minus battery box)...been looking for a slim oiltank to mount in there, but nobody makes one and I got no time. I'm using a little Ballistic 8 cell battery for mine. I'm likely mounting it into a box under the seet with the electrical THAT thing looks great!

PM with a price if you're interested.

[lucky]

Under 3.5 inches of trail would make for a very nervous front end..... Closer to 4 inches would be better....

I agree. But the XR750 was made for just racing.
It has only been lately all this interest in those racing bikes being put on the streets and calling them street trackers.
They are dirt track bikes with lights and license plates.

[johno]

Love the bike mate 
You will have to change the gearing lots, easiest way is to work it out is go to SOHC / 4 owners club web site , click on technical and then go to cb 750 gear calcultor a lovely XL spreadsheet wil pop up or down load .
Alll you have to do is put in your circumference , which at tyre diameter you quoted at 27.5 inchs equals 86.4 inchs circumference, go and just adjust the sprocket sizes one at a time until you get the speed you want at say 8,000 RPM.

You may end up with something like 17 / 46 or 17 /48

Lets see , thats around 150mph at 9,000 RPM      Oh yeh test the ol frame , geometry and tyres out . 
The V rated tyres are OK up to that and in the 21 inch you can get H or V ?
Enjoying your work,
cheers Johno

[Free Booter]

still inspired everytime I see it. Nice work.