Topic: 1975 CB750 Build! "Kona" - Sold and gone.

[Ravie]

Now that this build is just about over I have to look back a bit.

While I felt the build process wasn't terribly difficult, I look back at some of the things I said and was clueless about and even *I* think I was an idiot back then... While I have had and appreciate great help on this forum I think part of that is why this thread has many views but few posters. It's like watching a trainwreck. You don't want to get involved but you want to see the blood and guts!   

I had half a mind to take my introductory video down...I was so clueless in retrospect. It's hard to believe I was that naive about some things when I started. But like I said, this is the first motorcycle I've ever owned or built and it was DEFINITELY a process!  Heck, I had a job lined up at Twinline last fall. That's insane to me. If you had told me 2 years ago that I would have fallen this deep into these old Japanese bikes I would have laughed at you. Now I can't imagine life without them around.

I'm going to get this bike tuned and ride the piss out of it this summer and try not to kill myself or get killed by idiot drivers. We usually have a couple of moto-deaths each year in Topeka and quite often it is because drivers just plain weren't paying attention. I do not intend to be one of those deaths!  A full-face helmet, armored jacket, leather riding gloves and good riding shoes will be required gear on my bike.

I've got another frame but it has no title. Maybe someday I'll build another bike...  I would love to build a drag racer. Who knows!

Ryan

-----------------------original post----------------------
Hey ya'll.

Welcome to my motorcycle build thread, where Ryan changes his mind every 3 seconds and makes decisions and then goes against what he has decided. Such is life.

This is the first motorcycle I have ever owned and this will be my first bike build. I've been working on vintage and modern vehicles to include full restos since I was a kid, so I think I can tackle this without too much of a problem. I plan to rebuild the engine completely myself.

The name is a joke, sort of. I was trying to come up with a name for the bike when someone joked about "Well definitely not something that has anything to do with coffee"  Which sparked a long discussion that ended in the name Dark Roast.(now just Kona..) The color plans are flat black as much as possible except for the seat and tank which will be a "coffee" brown color.

I'm going for a sporty cafe style, one of the only bike styles I've ever had a keen eye for. I know it's "the thing" right now, but I'm doing it regardless of that. I just really like the style. Harleys bore me, crotch rockets bore me.

Below is my introductory video but know that a lot has been done since then (I'm updating this with 17 pages right now). I was a complete dolt when I made that video so pay no attention to my thinking that crap on the swingarm made it anywhere near the actual build...it went in the metal bin.

http://youtu.be/59MGfJ86jb4

Thanks and nice to meet you!

Ravie

[Tews19]

Welcome to the site! Swapping the damage free engine to the titled frame is definitely the way to go.  The modified swing arm looks kinda iffy. Clearance issues I would think. Use the search button and you will find lots of modified swing arm builds for the cafe look. Cafe overkill comes to mind. Member Godffrey built that bike. Check it out and it may give you some ideas.

From what I've heard club man's are a PITA when riding.  But to each their own. Me personally,  I always go with super bike bars. Cheap and great for all type of riding. 

[calj737]

Regarding that modified rear shock setup: uh, cut that off quickly! "Iffy" is a wicked understatement. If you desire a monoshock setup, there are some critical elements to engineer and fabricate, the least of which is correct shock. Using 2 shocks instead of a single unit that is designed with proper spring and damping rates is not a good design choice.

It also looks like the PO used angle iron. Again, not a great choice. There's definitely ways you can do it, and lots of great examples of it being done properly. I don't think that frame is one of them. Looks pretty unsafe to my eye.

As a guiding principle suspension (front and rear) needs to be engineered to be safe. Fabricating something, as the PO has done, that looks cool is not a sound approach unless it's been designed properly. Fortunately, you have an unmolested example to use when correcting or modifying that frame.

[Trad]

I'm with Cal on this one. Chop and weld the rear of the "paper work issue" frame onto the ghetto rigged, clean title frame. Or bring it to someone who can. That rigged piece scares me a little. 

[Ravie]

That's what I was expecting.

I'm sure you can guess what that ahem...issue..was..

Anyway, sure thing. It will come off. Thanks for confirming my suspicions.

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[SOHC4 Cafe Racer Fan]

That swingarm is unsafe, will have clearance issues and will make the bike much more difficult to turn.

[Ravie]

I looked at the swingarm. Will be easy to remove. Just cut that angle and pull the main bolt out. E-Z P-Z. Will use the stock piece from the other bike. There won't be any welding involved, just cutting out of the crap he added to the frame I'm using.

Squirted as many bolts as I could with penetrating oil to get ready for tear down. Looks like most of the main harness is missing from what will be the main bike. We'll see what kind of shape the one on the complete bike is in and if I can use it or if I will have to purchase a new one.

Build date is 10/74 on the frame I'm using.  The code I thought was the engine code doesn't seem to match the codes listed on http://www.sohc4.net/cb750k-serial-numbers/  that page, but it's obviously a K5. (E2420390)

[calj737]

If your budget allows, buy a MotoGadget M-unit to use as your electrical "harness". It makes wiring very easy, advanced capabilities, and highly reliable system. Runs about $380. Saves countless hours and headaches from troubleshooting 40 year old harnesses

[Ravie]

So, I had some free time today and decided to get the frame I'm using all torn down. I was successful. Managed to spill oil (and more water than oil...thank god I'm not using this engine!) all over the floor...that made things significantly more of a PITA.

So, the "complete" bike I got had Carpy's Clubman bars on it and...I hated them installed correctly. I could tell I'd be having to hold myself up every ride which isn't my personal idea of a good time. So Just for craps and gigs I installed them backwards and...I've got to say I like them better. I think they still look much better than the stock bars and I don't feel like I'd be doing pushups the whole time anymore. Anyone ever seen someone do that?  I know that's sort of the point of clubman bars (um...pushups and all that..) but...I like to be different.

With the huge long tank I'm going to use (does anyone know what that tank is from? I can't figure it out.) having those bars the way they were designed just has me reaching WAY too far.

If your budget allows, buy a MotoGadget M-unit to use as your electrical "harness". It makes wiring very easy, advanced capabilities, and highly reliable system. Runs about $380. Saves countless hours and headaches from troubleshooting 40 year old harnesses

Yeah. I think I may just get a new stock-style harness. They're only like 75 bucks...  The ones I have are terrible. The plastic is old and crumbly. I am not a rich man. haha

All I've got to remove of the "modification" he made to the rear suspension is cut off that angle. I've decided I'm going to use the Honda/Harley wheel he had done up. I like the fat tire. If I decide it's too short I'll just get a taller one.

A few pictures to illustrate...

[Greg H]

I like the look of your project ,and the more I look at the third photo the more it scares me . Whoever engineered that set up must have had a death wish,talk about form over function . Your work space is very much like mine ie organised chaos  , but I've got a hunch that your going to produce something good . Good luck  .

[calj737]

You said you spilled oil and water all over the place? What's the source of the water? There is no water at all in these engines; they're air-cooled and they are no radiators?

If the oil that came out of the engine has water in it, I got bad news for you...

When you finish cutting the franken-hacks off that frame, do yourself a favor and chemically strip it to bare metal. I would not usually say that, but that frame, I'd want to know that it was structurally perfect and not hiding some damage, crappy welds, or rust anywhere. Further, depending upon the weld process, it's quite imaginable that the PO but too much heat to the frame where those franken-mods attach, and he did burn through... It really needs to be thoroughly and comprehensively checked. For you safety.

Inspect the oil too. Make sure there's no gas or water contamination of it.

[Ravie]

I like the look of your project ,and the more I look at the third photo the more it scares me . Whoever engineered that set up must have had a death wish,talk about form over function . Your work space is very much like mine ie organised chaos  , but I've got a hunch that your going to produce something good . Good luck  .

The picture of the bike I haven't torn down yet?  It's pretty much stock except for that tank, which I'm going to modify the frame to fit because I like it and I don't have the money to spend on a new tank. I just need to make a rear bracket for it and lengthen the front one. That floor mat was just there because I flipped those darn clubman bars over because I was gonna be laying down doing pushups and I was curious how it might be if I used them upside down. Now they don't hit the Triple Tree and I can reach them..

You said you spilled oil and water all over the place? What's the source of the water? There is no water at all in these engines; they're air-cooled and they are no radiators?

If the oil that came out of the engine has water in it, I got bad news for you...

When you finish cutting the franken-hacks off that frame, do yourself a favor and chemically strip it to bare metal. I would not usually say that, but that frame, I'd want to know that it was structurally perfect and not hiding some damage, crappy welds, or rust anywhere. Further, depending upon the weld process, it's quite imaginable that the PO but too much heat to the frame where those franken-mods attach, and he did burn through... It really needs to be thoroughly and comprehensively checked. For you safety.

Inspect the oil too. Make sure there's no gas or water contamination of it.

Again, and I mentioned this before, I will NOT be using this engine. Yes. At least a liter of water and oil mixed came out of it. It's all drained out now, but I'm NOT using this engine for this build. The other engine is happy and has no water, etc.. I will be using the engine that is coming out of the more complete bike as I know that it was running just a few years ago (last tagged and ridden in '09). I haven't checked compression but I did oil the cylinders and kick it with the plugs out and it sounded healthy. I'm doing a complete rebuild anyway so I'm not worried about any minor stuff.

I plan to strip everything to bare metal, yes. To be honest I think the welds on it absolutely suck and they all look like cold booger welds. I think he actually didn't get enough penetration. It should be simple to take a cutoff wheel to them. I work at a large metal fab shop, so if there's anything wrong I can get help there.


As a side note - I really don't understand how that water got in that engine. It was mounted to the frame it came in and it was in a leak-free garage. The carbs were on, too. Beats me!

Has anyone had real good luck with vintagecb750.com?  They have quite a listing of parts at what look to be decent prices.

[Ravie]

Can anyone identify this tank? I'm gonna toss it on CL I think and get a better tank that already fits.




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[Ravie]

You know, wrenching ain't for the faint of body. haha.

I sort of "accidentally" went back out to the garage today. I started doing things and several hours later I was still working...haha

SO, I decided to tackle that dumb bracket. I was completely on base about the welds. Some of them were so cold that as I pounded and cut, some of them fell off the frame. Yikes!   

Aftermath of cutting


All cleaned up with a quick safety coat of rustoleum (I'm eventually going to strip the bike but wanted to protect them from flash rusting)


I took Greased Lightning and a wire brush and metal pad (one of those curly dish pad things you get at the dollar store) and cleaned up the frame as best I could. I figure once I do chem-strip it'll work better if it doesn't have 1/4" of grease to cut through, too 

I started pulling the other bike apart in between waiting for my slowass air compressor to refill. It is apparent to me I'm going to need all new electrics and a new main body harness at the very least. The wiring from the handles seemed OK though.



I'm going to need a new chain. The old one was rusty/crusty.

Also had a bit of trouble with the OF bolt which I have an adapter for my impact for...you cut a big slot and it works as a giant flathead on the end of your impact. It took a while but worked like a charm.



My body hurts. 

[calj737]

Make sure to replace both front and rear chain sprockets when changing the chain.

[Ravie]

Duly noted.

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[seanbarney41]

I think that is a CX500 tank that you were asking about.

[Ravie]

Thanks, Sean. That's what I came up with, too. Not sure where the best place to hock it would be but I think it's gonna go bye-bye so I can get a tank that will fit without modifications.

[Ravie]

Found out today that our paint guys at work also do powdercoat. Mwa-ha-ha...

Watched a How-to by Herm at DCC about forming a fiberglass seat...I'm pretty sure I'm going to attempt that.

I plan on keeping the wiring stock on my bike (but new harnesses)...  will LED's be relatively easy to wire in? I see there are some resistors you can buy to put in line (I imagine they stop them from glowing? not sure why a diode wouldn't work for this..)

Gonna chem strip this weekend. Hoping to get the engine out of the donor bike and get that bike all disassembled, too.

Amazingly, the old rotted tires and tubes hold air!  haha..

All I think about is this bike right now.

[Ravie]

Obsession.

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[SOHC4 Cafe Racer Fan]

Ryan,

I like your drawing.  I think it's good to have a visual goal in mind for inspiration and to keep you on track.  Of course, the drawings tend to change with the build over time, but it's something interesting to look at once you are "finished" to see how it matches up.

I'm really glad you are ditching that jerry-rigged swingarm.  It looks like a "fail" waiting to happen.  There have been many variations of extended swingarms and mono-shock set ups with other members' builds, but they looked much more sound.  A longer swingarm will tame wheelies (not so much of a concern with these heavy beasts), and they are generally used on drag bikes or for aesthetic reasons.  A longer wheelbase will give you more straight line stability for speed but decrease the bike's ability to turn.  I think that if your goal is a sportier cafe, then you should instead concentrate on saving weight and improving the handling and brakes.

I'm curious as to what the significance is of the number "27"?

Looking forward to more.

[Ravie]

Thanks for the reply. That's actually 21, which for no reason at all has been my favorite number since I was a kid.

Yeah, I like the look of the Avons I see a lot of guys using.

I'm ditching the stock air box, center stand, cutting down the fenders, and building a fiberglass seat. That should save a few pounds anyway.

I decided I'm going to use the cx500 tank and have someone here at work cut it short and weld in a flat there. When I make the form for the seat ill just butt it up to the tank.

Any thoughts on using LED's with stock wiring?

Carpy said he sells 2" risers for those clubman bars so I may try that with them flipped back down to their "normal" position.

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[calj737]

I just installed LED bulbs in standard indicator units. Bought them online form superbriteleds.com. $4/@ and they require no change in wiring or diodes...

[Roach Carver]

don't be too quick to ditch the stock airbox. It will save a ton of tuning and headaches. I've tried airbox, pods and just stacks. The box is the best all around followed by the velocity stacks and in the rear is cheap pod filters.

[SOHC4 Cafe Racer Fan]

Ryan,

The centerstand comes in handy, but you can substitute it with a rear paddock stand and save more than a few lbs.  I'm not sure how much weight you will save by losing the airbox.  You may hang onto it and see how it runs with it before removing it.  Velocity stacks look way cool and provide better performance, but they also provide more exposure to the elements (even with screens).  Many people don't like pods, but I've had decent luck with mine.  I agree with Roach: keep the airbox for now, and do not throw it away if you switch to something else.

As for LEDs, I have not simply changed the bulbs, the most inexpensive solution, but Cal has and did not need a new digital relay.  If you buy new LED indicators (not just bulbs), you can purchase a LED relay for approximately $10-20.  New housing or bulbs will not save much weight, but they will draw less current than the stock incandescent bulbs. 

Along with Carpy's site, you should check out Dime City Cycles for parts/accessories, and David Silver Spares US site for rare parts.  2 inch risers may help with the clubmans OR you could go with drag bars, eurobars or riser clip-ons if you still want a sportbike style ride with more comfort to your wrists.  The problem with clubmans is not just their height but the sharp angle, which is more severe than a pair of modern clip-ons -- one of the reasons I swapped mine.

There are a whole slew of tires out there.  The Avon Roadriders provide decent grip.  If you want something more retro but still grippy, the Bridgestone Spitfires are good, too.  If you plan on doing any cornering, I would rule out Firestone's; people like them for their old school hot rod look, but they have no contact patch for leaning at all.