Topic: '79 CB650 First Build

[colinbrogan]

Bought a project CB650 on ebay for $2k.  This thread will post my progress, along with tracking all my parts and costs. Let's start with images:

Below is the original image taken from the guy I bought it off of on ebay:



Here is the bike sitting in my current work space:h



The most salient thing to notice is the front fork. The first guy pulled it off a ninja ZX-7, with the claim that it will improve performance. I suppose the dual disk brakes would support that claim, we will see.

Next, he stripped and painted the frame black, rebuilt the carboretor and engine, painted part of the engine black, bolted it back to the frame. You can also see below the after-market 4 in to 2 exhaust pipes.



What is left is the electrical, air filter, chain, strapping on the carboretur, re-upholstering the seat, blinkers, mounting and plugging up all of the meters and ignition (on a fork they weren't meant to go on), spark plugs, bolting on the exhaust, putting on the chain, and finally starting it up.

I will begin with my plan for the carboretur and battery.

I have bought 4 emgo 48mm pod filters here:

http://www.amazon.com/Emgo-12-55748-48mm-Clamp-On-Filter/dp/B000VJSQ5Q

I plan to clamp them directly on to the carboretors, shedding the giant air cleaner case, for an open air feel.

To further that open feel, I am going to try and get a compact lithium ion battery to hide inside the bottom of the seat, so that there is open space all the way between the pod filters and the back wheel, in a manner similar to this inspiration:



I love the simplicity of this bike. Luckily, my current gas tank, seat, and frame color are similar enough to go strongly in this direction.

To elaborate on the battery plan, here are the parts I am looking at:

http://shop.antigravitybatteries.com/antigravity-batteries-ag801/

and

http://shop.antigravitybatteries.com/lc-fabrications-12-16-cell-battery-box/

I am waiting to hear back from these guys, because apparently you need a voltage regulator upgrade for these lithium ion batteries to  charge correctly (they are reported to turn into duds on pre-85 bikes, would hate to waste $250 in trial and error!)

I should be able to follow up by the end of the week when all my parts are in.

[SOHC4 Cafe Racer Fan]

If you are trying to achieve the look of your inspiration bike, you may want to source a CB550 gas tank.  It should fit your '79 frame directly, and is smaller and sits lower on the frame. 

Any type of magnetic pick-up or GPS speedo should work.

I don't think a new regulator is required, but it is a good idea to use a solid state regulator/rectifier.
Check Rick's Motosport Electrics (http://ricksmotorsportelectrics.com)  Just plug in your model information.  They have the reg/rec, plus replacement CDI boxes if yours craps out, stators, rotors, starter parts, etc.

[colinbrogan]

Gentlemen,
Invaluable information. Really glad I joined this blog a week ago or so and decided to post, I can already tell this will be crucial to the project.

I'll address Cafe Racer Fan's comment about the regulator first, since it is the priority for moving forward from here:

The last guy did upgrade the voltage regulator to one manufactured recently (but designated for CB650's in this year range). Here is a link to the exact model:

http://www.amazon.com/Electrical-Aha6024-Rectifier-Regulator-Nighthawk/dp/B0081SJYEQ

Any idea if this is solid state? If not, I will order a new one from your ricksmotorsport tonight.

[colinbrogan]

I just sent an e-mail to the manufacturer of that rectifier. I found the actual page for it here:

http://www.dbelectrical.com/p-12343-rectifier-voltage-regulator-honda-cb650-cb650c-nighthawk-79-82.aspx

I will post what their response, if / when they get back to me.

[SOHC4 Cafe Racer Fan]

That's exactly what you want.  I don't think there is any significant difference between that manufacturer and Rick's. 

[colinbrogan]

Great, I just ordered the lithium ion battery and cage.

[colinbrogan]

While I am waiting on the battery and pod filters, I will address the suggestion of a CB550 tank.

Looking around, it appears that both the cb650 and 550 have a 3.7 gallon tank, which makes me start to wonder if the one I have is a 4.7 off of a CB750. I could consider going down to the 3.7, which could shed some weight (6 lbs. less gas on a full tank + however less the smaller case would shed in metallic mass), it would certainly match the inspiration bike posted above. I assume the locking lid could just be drafted on to another bike, to keep the key matching the ignition.

However, as a web-designer by trade, it would be a cop-out to try and mimic the previously shown bike. Meditating on the look and feel of the current form, the bike has sort of a mean, front-heavy look. As much as I love an elegant cafe racer, with the massive ninja fork (the suspension is probably twice the diameter), front-disk breaks, more vertical positioning, the thing sort of looks like a charging bore. The bulge of a tall-sitting tank sort of naturally gives a stalky posture to the thing, and I think I will use that as the starting point of the spirit of the bike.

Moving rearward, bellow are a few seat styles I am considering. My friend is a talented upholsterer, and I plan to take advantage of that for use on this bike:



This one ignores the usual cafe tail panel, stretching flat all the way to the end of the frame. I bought a bigger bike originally to make 2 people more comfortable, so I definitely will want comfortable room for a second person on the back.

Returning to the contour and posture of the bike, I made a sketch below to attempt to familiarize myself with it's angles:



This sketch flirts with the idea of using 3 small headlights, set lower, as a way of giving reason to the broad shoulders and neck of the bike. Also, I have some sort of silencer on the end of an exhaust pipe which is probably terminating a little before the current foot pegs, with the silencer (hopefully if I can find one the right length), terminating right before the rear wheels. This sketch also assumes the tires are both bigger and the same brand / size / rims. I don't know much about the relationship between bike performance and wheel size. I am assuming the sprockets would have to have a different number of teeth to get the engine to wheel torque ratio right.

Below are color iterations, using the pencil drawing as a frame. Since I am stuck with the bronze colored shocks from the ninja, these iterations try to use bronze as an accent color.





Bronze exhaust tape and headlights buying candidates are listed below:



http://www.viperperformance.co.uk/productsearch.php?xscId=10091


Copper:
http://www.ebay.com/itm/4-1-2-ROUND-BATES-HEADLIGHT-COPPER-H4-BULB-CUSTOM-HARLEY-DAVIDSON-BOBBER-SPORTY-/331395707859?hash=item4d28b933d3&vxp=mtr
http://www.ebay.com/itm/vintage-torpedo-side-automobile-headlight-Copper-make-unknown-/171761453641?hash=item27fdc7ca49&vxp=mtr


Brass:
http://www.ebay.com/itm/OLD-SCHOOL-SOLID-BRASS-4-EARED-YELLOW-HEADLIGHT-HARLEY-XS650-BOBBER-SPRINGER-/231406124493?hash=item35e0e13dcd&vxp=mtr

Bronze:
http://www.ebay.com/itm/Black-Powder-Coated-Bullet-Headlight-with-Antique-Brass-Plated-Ring-Bobber-/231211215724?hash=item35d5432b6c&vxp=mtr
http://www.ebay.com/itm/Vintage-Antique-Pair-1910s-Cadillac-Headlamps-by-Gray-Davis-Brass-Headlights-/251941025848?hash=item3aa8daf838&vxp=mtr

[SOHC4 Cafe Racer Fan]

If you plan to ride this bike in anger or for any significant duration, the brat seat is going to get old really fast.  There's nothing to keep your ass from sliding rearward on quicker acceleration, and the lack of padding will start making your butt numb. 

Some people build their bikes for looks -- brat seats and Firestone tires.  Some build them for actual function and/or performance.

[colinbrogan]

Points taken, I suppose I am a dilettante at this point. Style over Functionality. Howard Roark would hold me in contempt.

But to prod your point, does pushing the foot controls back with another rear set ameliorate for the flat pan? I am speculating here, but I would assume that the forward gravity of leaning combined with legs tilted down and feet behind your body would hold you in place naturally, without the need of the seat matching your but contour. I don't know, would love to hear any opinions. If not, I am convinced, and will work on a different seat.

[SOHC4 Cafe Racer Fan]

Points taken, I suppose I am a dilettante at this point. Style over Functionality. Howard Roark would hold me in contempt.

But to prod your point, does pushing the foot controls back with another rear set ameliorate for the flat pan? I am speculating here, but I would assume that the forward gravity of leaning combined with legs tilted down and feet behind your body would hold you in place naturally, without the need of the seat matching your but contour. I don't know, would love to hear any opinions. If not, I am convinced, and will work on a different seat.

I agree with Cal.  Rear sets will help a little by making it less likely to slide off the motorcycle, but the lack of traction for your backside still puts added load on your arms, especially on take off.

At one time, I was considering using a brat seat on a build, but reconsidered -- but I am old and uncool anyway! 

Just some points to think about and disregard if you see fit.

[colinbrogan]

Yes, I am dreaming with the flat-seat a little beyond the logical consequences of hiding the battery in the seat pan. My thought was, though, that given a 2.25" depth on the lithium-ion battery, I could have it nest 1.125" into the seat, and 1.25" hanging below the frame, above the tire (assuming that position is not a vacuum tube for debris and rain by the wheel which would spin up toward it). This would not be a true brat seat, but kind of a hybrid with a slight slump up for the back passenger. All of this is speculative, though, I should wait until things come in. I have read in the Knott Motorcycle blogg that there is space under the gas tank. That AG battery is tiny and 1/6th the weight of a normal battery, I suspect I can find places to put it.

Staying on the subject of comfort, if you guys have any experience / opinions with this, I have another question. With the rear set further back on the bike and tilted posture, does that make things more awkward for a 2nd rider on the back, even with your ideally curved seats? If it did, I am considering trying to find different handlebars which would sit more upright like the standard cb650, and keeping the feet controls in stock position.

[SOHC4 Cafe Racer Fan]

Keep in mind that your passenger will have no grab rail so s/he will be pulling on you on acceleration, so "yes" it will be more awkward with a passenger.