Author Topic: cb750 racer build  (Read 5165 times)

0 Members and 1 Guest are viewing this topic.

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
cb750 racer build
« on: April 25, 2009, 06:04:59 AM »
I've been working on a major summer project and posting on dotheton a lot, so i figured i'd share this here too... i'm building a 74 cb750, with alloy tank, seat and fiberglass race fairing which will have a vac molded plexi windscreen.  this has been a real learning experience for me, as I usually do the body work in fiberglass only.  I'm liking the aluminum though as one off parts don't seem to take as long to do... I'm mocking up the parts on another 750 i have still assembled, then moving them over to the new frame.   


getting close to a finished swingarm, got the axle blocks back today from my machinist friend and they are KILLER!!! so I welded those up, forgot to tap one before I welded it and went DUH so now I'll have to come up with some kind of 6" tap extension before I can ride... got a 77lb piece of 1/2" plate steel for my jig too, seems to work really well, good and flat and great for clamping.  machined up my pivot tube too, it's got needle roller bearings and needle thrust bearings, and the swingarm is still 4lbs less than stock, should help the back end really stick to the ground!





tacking up the pivot tube to make sure everything clears before final alignment and welding, there's going to be a crosstube in there too, 2X1" al tube





Almost done with the body too!








almost done, just gotta weld on the shock mounts, and a tab for the brake bar and we'll be golden... I think had I had it all to do over again, I may have just powdercoated the old stock one....... I guess we'll see how much of a performance difference I get



all assembled, I'm actually going to do a more square alloy seat for it, the tank came out looking less round than I imagined, so now the seat doesn't quite match
« Last Edit: April 25, 2009, 06:11:55 AM by roccitycafe »
www.roccitycafe.com <- my sideline turned living

Offline SOHC4 Cafe Racer Fan

  • Speak up, Whipper-Snapper! I'm a
  • Really Old Timer ...
  • *******
  • Posts: 15,733
  • SOHC/4 Member #1235
Re: cb750 racer build
« Reply #1 on: April 25, 2009, 07:18:24 AM »
Hey Sean,

Great looking swing arm.  I think your aluminum Dunstall seat looks amazing.  Fantastic finished look!
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline FunJimmy

  • Who you calling
  • Old Timer
  • ******
  • Posts: 3,802
  • Vancouver
Re: cb750 racer build
« Reply #2 on: April 25, 2009, 10:35:22 AM »
It's a thing of beauty!

Keep us posted.

FJ
You never see a motorcycle parked outside of a psychiatrist's office!

CB550 Cafe Interceptor a Gentlemans Roadster
http://forums.sohc4.net/index.php?topic=27159.0

Offline ev0lve

  • Master
  • *****
  • Posts: 1,930
Re: cb750 racer build
« Reply #3 on: April 25, 2009, 11:11:40 AM »
Jaysus! This will be a righteous build. Subscribed!

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #4 on: April 29, 2009, 11:41:37 AM »
got the engine in!  starting to look like a bike now, and I love how there are so few extra things on this bike.  very minimal and light!

www.roccitycafe.com <- my sideline turned living

Offline cdoggy81

  • Enthusiast
  • **
  • Posts: 174
Re: cb750 racer build
« Reply #5 on: April 29, 2009, 08:51:00 PM »
very cool!

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: cb750 racer build
« Reply #6 on: April 29, 2009, 09:23:14 PM »
Looks good,
 Hope you are running a hardened shaft or collars on them needle bearings, and  that you are heat treating that swingarm..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #7 on: April 30, 2009, 04:30:52 AM »
the heat treater actually recommended a stress relief, I don't know if that restores temper, but I'll leave it in the hands of the pros
www.roccitycafe.com <- my sideline turned living

Offline papp101

  • Enthusiast
  • **
  • Posts: 174
Re: cb750 racer build
« Reply #8 on: April 30, 2009, 08:31:15 AM »
Excellent build, can you give some more details about your process on making the Front Fairing?

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #9 on: April 30, 2009, 04:09:00 PM »
Looks good,
 Hope you are running a hardened shaft or collars on them needle bearings, and  that you are heat treating that swingarm..

thinking more about this, the shaft is hardened, but there's no collar around the bearing unit, it's self contained and sealed, but do you think I should machine a bronze sleeve for it to distribute the load over a wider area?
www.roccitycafe.com <- my sideline turned living

Offline burmashave

  • Forum Immoderator
  • Old Timer
  • ******
  • Posts: 2,876
    • burmashave.net
Re: cb750 racer build
« Reply #10 on: April 30, 2009, 07:00:58 PM »
Very impressive build! I'm looking forward to progress as well.
Quote from: SOHC Digger, RIP
'Ere's whatcha do, Guvna', just throw a couple dookie logs in the hearth and bob's your uncle!
'77 CB750k

Offline kghost

  • Really Old Timer ...
  • *******
  • Posts: 6,855
  • www.facebook.com/RetroMecanicaAustralia
Re: cb750 racer build
« Reply #11 on: April 30, 2009, 07:03:08 PM »
Shame you bondo'd that tank....Aluminium looks so nice polished.

Dig your swing arm....May do one like that on my build.

Looking good.
Stranger in a strange land

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #12 on: May 01, 2009, 12:29:07 PM »
yeah, it's one of my first tanks, so it wasn't perfect enough to polish and i meant for the whole bike to be done in honda red anyway
www.roccitycafe.com <- my sideline turned living

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: cb750 racer build
« Reply #13 on: May 01, 2009, 08:19:58 PM »
What I was getting at on the needle bearings was, if they are not shaft size, then you either open up the holes in frame, or build sleeves to take up the difference.. but that would be tricky as they would be VERY thin.

Bronze aint the anwer, the bearings have to run on a hardened surface.. to the best of my knowledge
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #14 on: May 02, 2009, 05:33:32 AM »
oooh gotcha, yeah, the bearings are metric, so they fit on the shaft perfect, and they're a press fit into the swingarm pivot
www.roccitycafe.com <- my sideline turned living

Offline bill440cars

  • Feeling More & More,
  • Really Old Timer ...
  • *******
  • Posts: 12,358
  • Tryin' To Slow Down "Time"!
Re: cb750 racer build
« Reply #15 on: May 02, 2009, 11:40:14 AM »

       Have to agree with the others, about the quality of this build! :) So much attention to detail AND such features (swing arm, gastank, fairing, etc)!!!!!!!!!! :o 8) ;)



Member # 1969
PRAYERS ALWAYS FOR: Bre, Jeff & Virginia, Bear, Trevor & Brianna ( Close Friend's Daughter)
"Because HE lives, I can Face Tomorrow"                  
 You CAN Teach An Old Dog New Tricks, Just Takes A Little Bit Longer & A Lot More Patience!! 
             
Main Rides: '02 Durango, '71 Swinger & Dad's '93
                  Dakota LE 4x4 '66 CB77 & '72 SL350K2
Watch What You Step Into, It Could  End Up A Mess!

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #16 on: May 05, 2009, 07:51:39 PM »



almost finished with the exhaust... header pipes are all figgered out, just have to get the 1&2 pipes done from the headers back to the megaphones
www.roccitycafe.com <- my sideline turned living

Offline b20z

  • Full Member
  • *
  • Posts: 5
Re: cb750 racer build
« Reply #17 on: May 06, 2009, 01:20:55 PM »
Nice Build so far. What oil tank is that?

Offline 78CB750CAFE

  • I'm not really an
  • Expert
  • ****
  • Posts: 960
  • Ride, wrench, repeat.
    • Drewfus Nation, my podcast, bicycle collection, blog etc
Re: cb750 racer build
« Reply #18 on: May 06, 2009, 02:16:27 PM »
wow.
lots of work you have in this so far, can't wait to see it done.
any interest in doing swingarms for others?
"I believe in the bodies, I believe in the blood, I believe in salt around the rim of the glass because it makes us thirsty, and when we drink, then we all fall in love"
-212 Margarita by The Hold Steady
Build thread:http://forums.sohc

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #19 on: May 06, 2009, 05:18:13 PM »
wow.
lots of work you have in this so far, can't wait to see it done.
any interest in doing swingarms for others?

actually I have to build a jig to do a rework on the swingarm... if I do that maybe I'll look into building more of them, offer them for sale this fall after I see how this one performs, not sure of the price point though, the machined parts and material costs plus labor would probably put them in the neighborhood of $6-700, think there's interest there?
www.roccitycafe.com <- my sideline turned living

Offline moham

  • .fnord.
  • Expert
  • ****
  • Posts: 1,108
Re: cb750 racer build
« Reply #20 on: May 06, 2009, 09:15:40 PM »
What's the story with the motor? Have you done any mods there? Very convincing racer look so far. Something about a custom swingarm that turns heads...
78 750K-The Ocho
74 550-The Cherry Picker
70 750K0 motor-Dick in a Box

Offline themotoworks

  • addict
  • Enthusiast
  • **
  • Posts: 109
    • roc city cafe racers
Re: cb750 racer build
« Reply #21 on: May 07, 2009, 05:53:39 AM »
the motor is stock, just tuned up and checked over good.  the goal of this build was to get it done quickly, which is funny because it's been taking me a while since things have turned busy (not bad!!), i can't imagine how much longer it would take me with serious engine mods!! haha
www.roccitycafe.com <- my sideline turned living