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Is my bike ok?
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Discussion Starter #1
"Hackjob" '78 CB750 turning in to ......

...I really dont know. I have been fooling with this bike for awhile( I started in April this year) and progress has been pretty slow. Between lack-o-funds,work and other bikes I've been fooling with I have not had the chance to wrap this thing up like I hoped. Anywho,I hope to jump on this thing this winter and be riding it in the spring.

Here's what I started with. A 78 CB750K bought from a friend of a friend for $200 w/title.And a truck load of parts. I was able to sell of most of the extra parts and actually ended up making a profit of off it! He had been cutting on the frame years ago with the intention of hardtailing the bike but never did much other than butcher a frame. Good news for me,though. I have been wanting to mono-shock a CB for awhile now.

PART_1334428586681 by Shiny Ribs, on Flickr

PART_1334446846047 by Shiny Ribs, on Flickr

I got a s-arm for an early Ninja complete with all the linkages and shock off flea bay. It's roughly a 2'' stretch compared to the stock s-arm

SANY0090 by Shiny Ribs, on Flickr
Got the s-arm in the frame with a simple spacer on each side and located my mounts for the linkage thanks to some help/measurements from someone on this site.Sorry,I dont remember who but THANKS!

SANY0070 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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15,020 Posts
Discussion Starter #2

SANY0046 by Shiny Ribs, on Flickr
I got my upper shock mount worked in to what was left of the original frame...

SANY0108 by Shiny Ribs, on Flickr
...but I never have liked the ugly sheet metal joint where the backbone meets the cradles on these old CB's. So I decided to whack all that off and start over.Much happier now!

SANY0177 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #3
Much cleaner and stronger,I think.

SANY0176 by Shiny Ribs, on Flickr
I'm gonna be running an old Yamaha triple gas tank and an XR style seat/tail
The rear frame section for the seat looks crazy as hell,but it's super light( thats tubing,not round stock)and plenty strong to support my fat butt and the fiberglass tail section

SANY0051 by Shiny Ribs, on Flickr
All of my electrical bits are located under the left side of the tank.Completely out of view.I molested the mounts off the stock electrical plate and just tacked them on the back bone

SANY0019 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #4
Here is a mock up with the tank and seat on. Not sure if I'm gonna run these wheels or not. They are so dang heavy it's pitiful.

SANY0042 by Shiny Ribs, on Flickr
I originally was gonna run the 81 Honda Custom front end in these pics cuz of the dropped legs on the forks. I thought it gave the bike a bit of a sumo look to it,but these forks are just so dang small. Over the weekend I was able to fit a GXSR front end onto the bike.Thanks for the advice Mustapha,sorry I totally ignored you :) I'm pretty stoked about actually having good brakes going on this bike now. I have two other CB's ( one cafe-ish and a chopper) and I know all too well how much 70's Cb brakes SUCK !

SANY0064 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #5
These are dry sump motors and run an external oil tank. I didn't want that to show so I made (well,still working it) a tank to fit into the frame area right in front of the shock. I still have to mount another tank under the tank to give me full oil capacity and plenty of room for the tanks to breathe. A couple hoses to join it all together should be pretty easy to hide. I still have yet to figure out a filler cap area and a way to check the oil level yet. Like I said,still working on this part:)
Crappy cell phone pics

PART_1343275334056 by Shiny Ribs, on Flickr
Battery went under the seat. I'm planning on running some sort of side panels so that will be hidden as well. I really wanted to put this weight lower on the bike,just couldn't find another place it would fit.

SANY0041 by Shiny Ribs, on Flickr
Here you can see how well the oil tank hides right under/in front of the battery. Once it all gets powder coated black it should be near invisible.

PART_1343275414318 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #6
I've started building pipes for this thing,but haven't really settled on what I want to do with them yet.
Oh,heres a pic of the tank and seat before it got blacked out. You can see the lines a little better here.I wanted to see what the bike would look like all murdered out. Not sold on it yet.

SANY0031 by Shiny Ribs, on Flickr
First set of pipes I started on

SANY0039 by Shiny Ribs, on Flickr

SANY0038 by Shiny Ribs, on Flickr

And another set I have been fiddling with putting together. Nothing suits me yet,but the second set tucks away a little better.

PART_1344226022016 by Shiny Ribs, on Flickr

PART_1344225800387 by Shiny Ribs, on Flickr

PART_1344225800387 by Shiny Ribs, on Flickr

PART_1344225741987 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #7
And thats about it so far. I did mount my tail light/tag bracket. My next decision is whether to go with these heavy Comstars or something else. Obviously a GXSR front wheel would be an easy deal to just bolt on but I dont really want a short 17'' tire on this bike. I already reworked the ears on the ZX s-arm to hold a 20mm rear axle( what the CB's use) so I' kinda gotta work around that.Of course it can be changed in need be. Oh well,I'm oughta money for now so I guess I'll just try to brainstorm on the exhaust and see what I can come up with there.Oh yeah, I got a pair of Guzzi cans ( i liked the color of the finish) I gotta cut down and gut. Those dang things weighed 20lbs!!! Way too long for this bike too. Right now I am at $701 invested in this bike.I'm wanting to build a strong running 836 or possibly bigger engine for it. My original goal was to finish under $1500. I don't think that's gonna happen if I build the engine i want. I do know of some guys getting 90 rwhp out of some reliable 836's.That's the plan.Alright,well there ya go.Here's what I'm building and people keep asking what I'm building. Motard? Streetfighter?....I dunno. I dont think it really is either of those. I just tell 'em I'm building a hackjob. That is the official name of this bike right now:) Later guys.

SANY0048 by Shiny Ribs, on Flickr

SANY0102 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #8
Hmmmm,I might now be using those Guzzi cans after all. I messed around with the exhaust some more and came up with this. Small,light and not real noticeable. I might stick with this setup. Maybe put a small baffle in each side. Thoughts?

PART_1350961473630 by Shiny Ribs, on Flickr

Good Lord,that kick stand is ugly. Gotta do something about that.

PART_1350961494932 by Shiny Ribs, on Flickr
I mounted some junk tires to get a better feel of the mock up today. 110/90-19 front and 120/90-18 rear. Not a real big tire,but I like the tallness of them. it's the main reason I want to run these 18 & 19 inch wheels. But,I weighed the complete rear assembly-wheel,rotor,cush drive,sprocket and tire comes in at a whopping 48 pounds?!?! Holy sheet thats heavy! I turned the wheels silver side out and I gotta admit I'm kinda digging the silver wheels against the blacked out bike. Might just stick with this setup.But who really knows....The weight of the bike is sitting on the rear suspension in these pics. The GXSR gives me 1.5'' of drop compared to stock forks.The front tire is sitting 1'' below the surface of the table right now. With the front end under weight I hope to come in with a slight nose down stance that I was hoping for.

PART_1350962283763 by Shiny Ribs, on Flickr

PART_1350962306636 by Shiny Ribs, on Flickr
 

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Is my bike ok?
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Discussion Starter #9
I sat on the bike today and the foot pegs felt too high with this seat. 1'' lowered felt just right. I'll get to work on those soon. I want to get my bars sorted out while I am it so it sits comfy. I dunno if I;m gonna mount risers for 7/8'' bars or make something else.Def dont wanna run clip ons on this build,shooting for bars on this bike.I love the dirtbike bars on my 76 CB750F so I'm sticking with that setup here. Suggestions?
 

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Bitches love Fighters
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5,325 Posts
those wheels with those forks look great. definitely use that setup.
 

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Is my bike ok?
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Discussion Starter #12
I like the proportions and stance a lot. Cant wait to see more progress.
Thanks! Hope to make some real progress on this bike over the next few weeks.

those wheels with those forks look great. definitely use that setup.
Thanks man,glad someone else agrees! Everyone else is busting my balls to run modern wheels. I just dont think they jive on this bike. Old tins need big rims IMO.


What do ya'll think about a 70/30 knobby on this bike?Bad idea. I wonder how they handle????
 

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2,225 Posts
I like the look of those wheels a lot, but consider if you're happy with 90hp on a 120 rear tyre?

Also, more modern stock wheels will easily cut the 48lb you've got there down to about 30lb, which will make a real noticeable difference both to handling and the speed your bike revs up at.

The front will also have a significant benefit. How are you going to run big fat 70's discs through modern calipers? It won't work. So at the least you'll need to fit modern discs to old wheels, maybe you're lucky or maybe you need adapter rings. Then consider the weight difference of thick undrilled discs versus bigger, thinner, drilled discs and the effect this has on "flickability".

Odd size wheels means odd sized tyres. These will only be available in bias ply, no radials for you. This means they're heavier, and don't grip or steer as well as more modern rubber.

Go with the old wheel by all means, it looks cool, but don't try to think they'll work anything like as well as newer stuff.
 

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Is my bike ok?
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Discussion Starter #16
Thanks for the comps guys.

a morti- youre spot on bro. Everything you say I agree with 100% . I got all those thoughts swirling inside my limited brain space as it is.Do you think 90 rwhp is too much for a 120? I dunno. My other bike only makes 55 rwhp so I got no idea how that will act. My 55 rwhp does even attempt to spin.It'll just stand up if I clutch it.otherwise it just bogs. LOL If I stick with these wheels I'll def go with adapter plates and modern rotors.The old Cb rotors have poor friction coefficient ,or however you say that.And they squeal like a pig! I might end up HAVING to go to a small set of wheels.Looks like I got some serious front tire to header clearance right now. I gotta get these forks despringed and see what I'm working with. Got one header and muffler done tonight. Can't get to the other side til i turn the table around.Wish it had casters!

SANY0074 by Shiny Ribs, on Flickr
Wrapped the baffle with header wrap.Looks hokie but it has held up for 8,000 + miles on my other bike

SANY0075 by Shiny Ribs, on Flickr

SANY0076 by Shiny Ribs, on Flickr
Pipes and muffs come in at 8lbs per side.Not too bad

SANY0078 by Shiny Ribs, on Flickr
Shaved the side covers and made a lexan window for the sprocket cover.May end up with a LED in there.I figured this helps kill some the the vintage look of this old motor. I want a mechanical look for this bike,if that makes any sense

SANY0069 by Shiny Ribs, on Flickr
Got the side stand angled up.Looks a little better now.Still ugly.Gonna hold off on any other mods to it til I get her on the ground.I dont know what the new ride height will dictate needed to this thing

SANY0082 by Shiny Ribs, on Flickr
 

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Can you take a better photo of the window you made for the sprocket? I like the 'mechanical' look of things too. Have you ever seen frankenstuffs points cover? I have one, its pretty cool if you decide to keep the points around...

[/url] Untitled by [email protected], on Flickr[/IMG]
 

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Have you ever seen inside a typical sprocket cover? Your options are going to be remove and clean it every ride, or quit lubing your chain...
 
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