Author Topic: Project BCC Racer - CB750 frank cafe build on a Yammie Frame  (Read 10989 times)

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Offline speedfoos

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Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« on: September 02, 2013, 06:20:10 PM »
Right, I'm new. I like to work on things that consume oil, gasoline and money.  I've been a wrench for a long time now. I like working in my garage, I don't really like people.  Projects have been turbo'd Honda Civics, V8s stuffed in old Volvos, a love/hate relationship with my Nissan Frontier (recently converted from auto to manual), I've got a Harley that is too expensive to buy parts for so I don't, and then I picked up a basket case on Craigslist for $300.

Here it is, a '79 Yammie XS400.



Key thing I like about it is that the frame has a clear title. The guy dished one side of the tank as well as the top, lied about a seized motor, bent valve and flat spotted cam and a host of other issues. But hey, its a project so I'm cool with it.

I've been grinding on the frame, taking bits off it, smoothing things out. It's got a Yamaha Radian (unknown year) swing arm, a misc Yamaha front end, and had some bull#$%* front pegs welded to the frame. I grabbed an extra set of sportster shocks and mounted them up.




And then a guy over on TCU sent me an XS650 tail hoop that I straightened, widened and slugged into the frame. In retrospect, I shouldn't have straightened it, but more on that later.




All that took me about a year what with deployments and stuff (been in the Army 16 years now) and I've finally found some moto to get this project done. I got a killer (I think) deal on the CB750 motor with carbs and oil bag, but it turns out that a CB750 motor is way too big for an XS400 frame.

So I stretched the frame three inches.




With the slugs tacked in to place, I wanted to see what the stance looked like.




Yeah, I dig it. Went to Bull City Rumble in Durham a few days ago and saw a bunch of cool bikes that gave me some great ideas and motivated me to get cracking on the bike.

I bought a bag of play sand, scraped the rest of the paint off the tank and paused for a photo op.




Then I grabbed my ball peen hammer and did work.



Not bad for my first attempt. Sure I'll have some bondo work to do but I'm okay with that.  I evened up the tank dishes today so they're nearly the same now, close enough that there isn't anything noticeable anyway. Then I welded up the two holes on the left side of the tank from the old emblem, threw some primer on it so she won't flash rust and set to getting it mounted properly. I cleaned up the tank mounting brace, positioned it where I wanted and welded it up.




Remember what I said about wishing I hadn't straightened the tail hoop? Yeah, with my fat ass on the bike, I had zero clearance for shock compression between the tail hoop and the tire. Instead of moving the shock mounts like I thought originally, a guy on TCU suggested I bend the hoop. Good idea.

Getting everything set up.




Donned my OSHA-certified welding shoes. Safety always kids.




Yep, got clearance now.




Next step will probably be tackling the rear fender because I want to see it, no other reason. That said, I have no idea how to wire this thing up. I've been searching around and have discovered the coils I need to use (5-ohm ones) and have looked at basic wiring, but need to wire the bike from scratch and all I have is a handful of odd XS400 wiring and whatnot. I know these are simple and the only thing I need really is the regulator/rectifier, a flasher for the turn signals (to help with resale when I'm done) and the brake switches. Oh yeah, brakes should be fun. Regardless, I'm learning as I go and having a good time. Once I do fender, I'll move on to motor mounts and then make the rear sets for it.
« Last Edit: September 07, 2013, 05:33:00 AM by speedfoos »

Offline BPellerine

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #1 on: September 02, 2013, 06:36:46 PM »
the stretched engine bay is cool.surprised there are no cbs done that way .looks long and lean!bill
1978 CB 750K ard and webers
another anfob

Offline speedfoos

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Re-post because of the damn Captcha
« Reply #2 on: September 02, 2013, 06:48:38 PM »
OK, this stupid Captcha thing is getting old. That's the second time I've lost a post because of it. Hopefully its not a permanent thing and is only there because my account is new.

Anyway, I would imagine it isn't done very often because it's a pain in the ass. Especially when you can buy a frame that fits your motor of choice for next to nothing on these old bikes. The only reason I did it is because I'm stubborn and cheap.

Offline apetersonboy

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #3 on: September 02, 2013, 09:19:33 PM »
That stance is gnarly!

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #4 on: September 03, 2013, 05:06:56 PM »
Thanks. We'll see how things balance out with the full weight of the bike to see how I'll even it out.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #5 on: September 04, 2013, 05:43:32 PM »
Moving right along. Got home from work and took a stab at the rear fender tonight. Did a little measuring and figured I need to narrow it by an inch and shorten it by about 3-1/2 inches. So I grabbed the old masking tape, square and Sharpie to sketch things out.




Seemed pretty simple so I grabbed my favorite tool (4-1/2" die grinder) and got to cutting. A few minutes later that was done, cleaned up the edges with a flapwheel disk and tacked things up.




I massaged a few places with my ballpeen hammer, stitched the entire joint up and smoothed things out with a 40, then 80-grit flapwheel. I'm happy with it. It's not perfect because if it was, building bikes would be a career not a hobby. Besides, Bondo is the great bodywork equalizer.




And now for some mock-up shots. I'm quite happy with the way it's going to look.






Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #6 on: September 06, 2013, 10:52:47 AM »
Right, so we've been bandying this around the office this morning and I think I've got my mind set, but thought I'd stimulate a little conversation here and get some other viewpoints. Namely from people who build and ride bikes as a primary hobby.

Situation: CB750 cafe build. Dual-disc hydro front with a mechanical drum rear
Goal: Functional, but clean and simple, not a racer, more of a bar hopper but I don't want to sacrifice a lot of safety.
Idea: I want to keep the bars as clean as possible so I'm thinking about removing the front brake control from the bars, snagging a rear master cylinder and linking that up to the pedal and simply removing the rear brake functionality all together.

Pros as I see them: Front brake being the most important, it's still there. Cleans things up, which is my primary goal. Burn-outs become super easy now.
Cons as I see them: If things go squirrely in a turn, I'm #$%*ed if I forget to straighten the bike before laying on the brake.

Extra work is not a concern because I have to fabricate everything for this build anyway (CB750 motor in an XS400 frame).

Thoughts?

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #7 on: September 06, 2013, 03:59:12 PM »
Yep. I keep my thoughts to myself too.

Anyway, attacked the frame with a cutting torch and some more flapwheels today. I drilled a couple holes in the hold peg mounting spots in an attempt to create the spot for my lower engine mount brackets. That didn't work out so well so I decided to just go clean slate on them to ensure everything is straight when I go to hang the motor.

While oxy/acetylene is quick, it is definitely dirty.





But that's why Jesus invented flapwheel sanding discs.




Oh, and I scored a set of R6 rearsets with all the linkage and whatnot for $75. I'm chuffed about that deal.

Offline Tews19

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #8 on: September 06, 2013, 06:38:08 PM »
Welcome to the site! Very interesting build that's for sure. Subscribed!
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline Tews19

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #9 on: September 06, 2013, 06:41:02 PM »
What's the vin on your engine if you don't mind.
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #10 on: September 06, 2013, 07:52:44 PM »
Dunno. Will have a look in the morning and post it up.

Offline Tews19

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #11 on: September 06, 2013, 07:58:24 PM »
I think if you change your title to mention YAMMIE frame the frame builders will take a peek... This is seriously an interesting/cool build with the frame choice.. Shame if more do not know it...
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build
« Reply #12 on: September 07, 2013, 05:36:24 AM »
I think if you change your title to mention YAMMIE frame the frame builders will take a peek... This is seriously an interesting/cool build with the frame choice.. Shame if more do not know it...

Done. Not that I'm an attention whore, but it is nice if someone catches me before I do something permanently stupid on a project.

Oh, here's the motor VIN: CB750E-2464160

I'm sure that means I got an extra special Russian version of the bike or something like that, right?

Offline Tews19

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #13 on: September 07, 2013, 05:40:10 AM »
LOL no it's not a special KGB engine... I was curious if it were a K1 and lower...
Do you think the frame will flex since it was meant for a 400?

Do you plan to raise the rear end or keep the lower stance?
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #14 on: September 07, 2013, 08:55:22 AM »
Nope, just an old K5. 

I plan on adding a couple gussets here and there to help with the frame flex potential, in fact I may stitch a couple perforated strips of 14 gauge along the backbone under the tank. Frame flex is definitely a concern for me but I will address that once I finish up with the engine mounts.

I like the rear where it's at, but am not going to try doing any leveling until the bike sits fully dressed with new fork seals and fluid so I can see exactly how it sits. If I start messing with things now, there's a good chance it will be all out of whack once it's hung with its full weight.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #15 on: September 07, 2013, 01:42:53 PM »
Didn't do a whole lot today. Made a quick little engine mount template so I don't have to lift the motor in and out while I set things up.






And then I cleaned the garage as I had metal grit all over the place and it was getting on my nerves.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #16 on: September 08, 2013, 11:25:08 AM »
Was kicking around a few ideas on how to mount the motor so it won't vibrate the fillings out of my teeth. My Harley is rubber mounted, which is a definite plus for something as poorly engineered as a 1450cc motor that only puts out 70whp. Obviously a linear 4-cylinder Honda engine is a whole different animal, but it will still vibrate. I bandied about with rubber bushings, re-purposed sway stuff and finally hit it at Lowes today.

I will seat these bronze bushings into all of the mounts. Universal size, just the right amount of dampening and they are $3/each. All I had to do was drill a hole that slightly too small, heat everything up with acetylene torch and press them in with my vice.


Offline 754

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #17 on: September 08, 2013, 11:34:42 AM »
 Just a suggestion, dont even bother .. We all use solid mounts..for good reason.



Here is a 750 in a 175 frame.

W i have triedto post to this thread before, but seem to have trouble with it ? No idea why?
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 Tews19

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #18 on: September 08, 2013, 12:24:02 PM »
Frank, does that run?>
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline 754

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #19 on: September 08, 2013, 12:47:15 PM »
 He did run it on the ice a few times, i built a few bits for it. When it was created.
 Then when i saw it this spring.. It was out in the weather on its side as they were prepping to dismantle the owners estate.
 So i ended up with it..but I cut it up right away.. It looked as in the pic but no seat and Red Kawi tank on it . Turns out the alternator delete cover that looked just like mine.. Was in fact mine ! Was wondering where it had gone..!
 It was not what you would call a pro build...to be kind..
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 speedfoos

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #20 on: September 08, 2013, 01:50:03 PM »
Honestly I like the look of the bushings. Plus it will be a nice detail when everything is all painted up and the bushings are polished. Can't hurt to have the mounts bushed.

Offline speedfoos

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #21 on: September 08, 2013, 05:34:51 PM »
Not too much finish out the weekend. I had a look at my center stand and discovered that I stand to lose 3" of ground clearance if I use it. No thanks. So out comes the torch and off come those mounting brackets. Took the stock XS400 front motor mount tabs off too while I had the flame out.




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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #22 on: September 09, 2013, 04:41:02 PM »
Looking forward to the end result.

Offline Roach Carver

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #23 on: September 09, 2013, 06:46:34 PM »
marked to see wtf happens next.

Offline Tews19

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Re: Project BCC Racer - CB750 frank cafe build on a Yammie Frame
« Reply #24 on: September 09, 2013, 07:06:38 PM »
marked to see wtf happens next.


LOL.. I think this guy will finish his build though... I've been here a few years and seen a bunch of builds with non Honda frames or engine but into a Honda frame flame out....

This guy is a yooper... He will get'r done!
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.