I originally bought this bike in 2004 after I wrecked my 1988 Super Magna. The plan was to ride it around in stock form while I fixed the Magna, and then chop it into something ridiculous. The chopping part happened before I got around to fixing the Magna, and here’s what came out.
Parts
This is a true one-of-a-kind traditional frankenstein chopper. I used Honda parts whenever possible, aftermarket for the minor stuff, and plenty of custom-made parts.
- Frame: CB900C ’82, modified
- Engine: CB900C ’82, rebuilt
- Carburetors: 34mm Mikuni, from ’81? Suzuki GS1100E (I think)
- Carb boots: Custom-made from two diameters of radiator hose, 1.5″ and ?
- Carb reinforcement mount: custom-made
- Exhaust: ’93 CB750SC Nighthawk header tubes, with 1-3/8″ OD tube tacked in after the underside bend
- Wiring Harness: full custom
- Fuse Box: custom made, under tank
- Battery Tray: custom made, in/under swingarm
- Front Seat: VF700C ’87, re-covered
- Rear Seat: VF700C ’87, “interestingly” mounted
- Fuel Tank: VT1100 ’87-’94, repainted and petcock mount moved
- Forward Controls: Mapam Restyling Universal, on custom-made mounts with custom-made linkages. One linkage piece pulled from some 1979 Suzuki, the other fabricated from a 1980 CB900C brake pedal.
- High/Low Suicide Shifter: Custom, with skull on top
- Swingarm, shaft & joint: GL1200 ’84, U-joint shortened
- Rear wheel and rotor: GL1200 ’8?
- Rear Brakes: CB900C ’82
- Final drive: GL1200 ’8?
- Rear Suspension: Harley Dyna OEM shocks
- Rear Fender: None, but it needs one
- Triple Tree: GL1100 ’81
- Forks: VT750 ’83
- Fork Brace: GL1200 ’85
- Front Wheel and Rotors: VF1100C ’83
- Front speedo gear: VF1100C ’84
- Front Axle: VF1100C ’83
- Axle and caliper mount spacers: Custom-made
- Front Brakes: VT700 ’85
- Handlebars: aftermarket 10″ apehangers (7/8″ tubing)
- Hand Controls: GL1100 or GL1200, don’t remember. Shortened throttle sleeve for standard 7/8″ grips. Changing out for different ones.
- Headlight/turn signal mount: Aftermarket
- Headlight: GL1000 ’76
- Turn Signals: Aftermarket fluted bullet lights
- Tacho and Speedo: Aftermarket 2.25″ mechanical drive
- Oil Cooler: ’93 CB750SC Nighthawk
- Wet weight: 650? pounds
- Horsepower: 75hp at 8000 rpm (less HP, more torque)
- Fuel Capacity: 5.0 US gal, including 1.0gal reserve
- Engine Oil: 4.7 US qt
- Transfer Case Oil: 0.6 US qt
- Final Drive Oil: 0.2 US qt
- Final Drive: 2.89:1
- Primary drive: 2.04:1
- Secondary Drive: 0.72:1 low, 0.62:1 high
- Seat Height: 26 in
- Wheelbase: 69 in
- Ground Clearance: 6.5 in
- Rake: 33 degrees by my measurement – 4.5 degrees over stock
- Trail: 4.25 in
- Compression Ratio: 8.8:1
- Octane recommendation: (r+m)/2 method, 86 octane or better
- Spark Plug gap: .9mm (.035in)
- Valve Clearance (cold):
- Intake: .127mm (.005in)
- Exhaust: .20mm (.008in)
Replacement Parts:
- Spark Plugs: NGK DPR8EA9 works fine. There’s a compatible Autolite plug if you’re really in a bind.
- Oil Filter: Fram #6009. Available at Wal-Mart and most Auto stores.
- Tires:
- Front: 110/90-18
- Metzeler ME880 Marathon
- Rear: 150/90-15
- Dunlop Elite II or Metzeler ME880 Marathon
Modifications
Frame:
The original frame was used. Any unnecessary pieces of metal have been ground off the frame. There were a lot of accessory mounting pieces on the frame in strange places.
- (Done) removed the steering lock and turn stopper from the steering neck. The new triple tree didn’t mate up with either one. I might weld my own steering stops onto the neck later.
- (Done) I built a custom fuse box to replace the god-awful beast that used to sit right under the ignition. It’s a 4 blade fuse design. I zip-tied it inside the triangle section of the frame, a few inches behind the ignition coils.
- (Finally Done!) The kickstand has been seriously relocated. A custom mount was made out of angle-iron and welded to the swingarm. Using the upper part of a stock kickstand, a new and VERY LONG kickstand was made from 5/8″ solid steel bar. The weight of the bar required more spring tension to hold it up while riding, so the upper perch of the retainer spring was moved off the stock mounting plate and onto the swingarm.
- (Done) The seat beams (used to support the tank rear and the battery housing originally) are lowered 0.5-1 inch in the front and 3.5-4 inches in the back, with a cross-bar across the rear made of 3/4″ 12 gauge steel tube. The frame support for the rear of the tank needs to be supported, but the current bridge-tube gets in the way of the new tank. I’m going to use the same 3/4″ 12-gauge tube stock to create a cross-beam just under the existing support tube and weld it up.
- (Done) A super magna front and rear seat have been used. Because of the electrical relocation and the frame bar changes, no modifications will be needed to the seat itself. It will fit perfectly onto the frame of the CB900. However, I will have to fabricate different metal tabs that bolt from the bottom of the seat to the frame – they need to be wider and a little lower.
- (Done) The frame cross-member that goes across the top of the rear seat area (above the shock mounts) has been removed. A new rear-section was built to mount a really nice sissy bar I got for free from a friend. Solid steel shank reinforcement holds it to the original frame.
- (Done) Side Covers – I made side covers out of aluminum diamond plate, mounted to the bike via cotter pins w/ rubber grommets. The new ignition and other control switches will be mounted on this side cover, eliminating all of the wires and electrical controls from the handlebars.
Engine work:
I bought the bike thoroughly used with 60,000 miles and a very recent rebuild. The guy was certainly no master mechanic and didn’t rebuild it well at all.
- Head gasket: The head gasket is leaking pretty bad near cylinder 1. It needs to be replaced.
- Valve cover gasket, bolts, and bolt seals: I’ve bought all-new bolts, bolt seals and valve cover gasket. Many bolt holes were stripped and re-tapped with SAE threads and bolts. The valve cover overall leaks like hell, but that’ll be fixed when I put in the new stuff.
- (Done) Carbs: the stock 36mm keihins were pretty spanked. One of the jets is stripped into the carb and can’t be removed. I’ve replaced the carbs with 34mm Mikunis off a ’81 Suzuki GS1100E. I had to make custom boots from 1.5″ spa/pool hose. I’m going to try to make better boots out of radiator hose- the rubber should grip and seal better. The main jets that came in these carbs were 122.5 and the slows might have been 45. Need a special screwdriver to get to them. The low-end power is MUCH better than it was before, but it’s still running lean in the top-end. I will probably have to upgrade the jets in order to fix it.
- (Done) The clutch basket bearings were destroyed. Really destroyed. The clutch would make the most hideous clatter, and shake itself into slipping under heavy load or at high RPM. The bearings have been replaced and the clutch noise is now pretty normal for a 24-year-old bike with a bad basket design
Rake and front end:
The CB900 has 28.5 degrees of rake stock. However, the stock triple tree has a negative rake on it! I’m not sure of the number but based on some measurements of high-res photos I’d wager a guess of 3 degrees. This means that the frame itself has a stock rake of about 31.5 degrees. With the lowering of the rear end, I’d estimate that the rake is 33 degrees. By doing measurements of photos, it looks to be just over 33, like 33.2 or 33.3 degrees. The trail is 4.25″ (a quarter-inch shorter than stock). I’d like a longer trail, but I don’t see a good way to get it other than by raking out the steering neck some more.
- (Done) I took a triple tree from an ’81 Goldwing (39mm forks, 8.4″ spread and same neck length, but no rake adjustments). The stock ignition control is mounted straight to it. I’ll eventually relocate this to somewhere hidden, either under the tank or seat.
- (Done) I got the front wheel off an ’83 Magna V65 – the same style as the 1983 CB1000C. Real nice looking wheel (compared to the Comstar’s)… MUCH better rotors than on the CB. Also needed the V65′s speedo gear because of the different rotor mounting stance.
- (Done) Forks – 1983 Shadow 750 forks… Dual disc, no TRAC, removed air ride (it was optional on the shadows- 0 psi was fine), of course 39mm diameter, my favorite. They have a slightly different look than the stock shocks (no ring grooves on the fork lowers). Like stock, they have the forward-set axle to slightly reduce trail geometry.
- The fork uppers are being replaced with 6″ longer tubes and progressive springs. This will raise the front end quite a bit, allowing for better ground clearance and overall evil appearance.
- (Done) front brake calipers and mounts from a 83 Shadow 750. Reused the stock brake hoses because they’re about 1.5″ longer than the Shadows’. Used a brake line splitter from a GL1100 because it mounted best to the triple tree.
- (Done) The V65 Magna axle sits about 2mm inside the forks on the right (it was made for a narrower spread). A stretch, but it works. Spacers had to be fabricated for the axle. The right side went from 27mm to 33mm, and the left side got a new 7mm spacer. All of the bolts for the brake caliper mount plates needed 7mm spacers as well.
- (Done) Fork brace from a 1200 Goldwing. Perfect fit.
- (Done) Front fender from an ’88 Super Magna.
- (Done)Stainless Steel brake hoses all around. 40″ rear, 23″ front master cylinder, 21″ to front calipers, plus the length of the joints. I could have probably gotten away with 21″ from the master cylinder.
- (Done)Stainless steel extended clutch cable and stainless tach cable from Barnett Cables. TOP notch work, better than the Motion Pro cables I have.
- (Done) Turn signals mount directly to the side of my headlight mounting ears (see chopper link below). An old 7in Goldwing headlight sits inbetween. That light is HUGE!
Controls and bars:
- (Done) 10″ high mini ape hangers are mounted straight to the triple tree. Originally I had these 4in Dogbone risers mounting up to the bars from an ’86 Rebel 450, but it was cluttered and ugly.
- (Done) I took some controls off a GL1100 or GL1200 (I forget which) that use the same wiring harness as the CB’s controls. I had to move two pins on the left control harness to make them work. Since the color coding is the same between the bikes, a quick glance at the old and new control harness made it easy to fix.
- (Done) a single throttle cable runs down to the carbs.
- (Done) I have a good master cylinder off a 83 Shadow 750, plus a chrome reservoir cover. A spare (identical) master cylinder from a GL1200 is sitting around in case I need it.
- (Done) For gauges I’m using these 2.5″ generic aftermarket units. They’re just straight up cool. The electrical for those is run down the center of the steering neck (it’s hollow).
- Grips… gotta get new grips once the new controls are finished.
- (Done) I have fabricated forward controls that mount to the front-most engine mount points. I made spacers out of 3/4″ steel rod (length 4-3/8″) that go from the frame to a 5/16″ thick steel plate. 10mm (about 3/8″) drilled holes to the frame, 12mm (about 1/2″) drilled for the peg bolt.The spacers are held in place by 10x160mm 1.25-pitch bolts on the left side and 10x200mm 1.25-pitch bolts on the right (Honda Parts). I had to add about another 5-10mm thread to each of the 200mm bolts. They really only need to be about 180mm long, but Honda doesn’t offer any in that size. The part numbers are 95800-10160-00 and 95800-10200-00.
I have Mapam Restyling Universal Controls that are bolted to the steel plate. The Mapam controls come with two heim joints and two clevis-type joints, tapped to 6.0mm/1.0 pitch. The shifter linkage rod is made from 3/8″ rod, and the brake linkage is made of 1/2″ rod. The brake linkage lever is made out of the old pedal mount piece, chopped and flattened around a piece of 5/16″ plate. This piece has been drilled to allow for the clevis joint to pivot as the brake is pushed.
- (Half-Done) I am making a suicide shifter for the high/low gear. I’d like to put a big chrome skull on top. I’d also like to put LED’s in the eyes that are hooked to the ignition coils, to flash with the spark. In the meantime, the original gear shift lever has been flattened and had the toe cut off. It’s hooked up to the high/low and can be ‘kicked’ into the right gear.
Rear end:
- (Done) Swingarm – GL1200, which is 4 inches longer than stock. With the swingarm and new front-end, the wheelbase is now 68.75 inches, and it’s gonna be longer! ** NOTE **: The driveshaft has a longer thrust out from the swingarm housing on the GL1200. I had to shorten the U-joint by at least 1/4″ in order to let the swingarm mount up properly. To play it safe, I cut about 1/2″ off the long side and 1/4″ off the short side. It was SO close to mounting without the shortening, but I don’t trust its behavior during potholes and other heavy load on the rear suspension.
- (Done) Final drive – GL1200, 2.89:1 versus the 3.08:1 of the CB. Lower RPM for long-distance cruising.
- (Done) Wheel – GL1200 – 150/90/15 stock.
- (Done) Shocks – from a late-mode HD Dyna. American bike, but Japanese shocks!
- (Done) Electrical Relocations – I built a custom pan for the battery that lets it hang inside/below the open gap in the swingarm. The electronics have been moved to a folded piece of 26ga sheet metal that mounts across where the stock mud-guard mounts (JUST above the new battery location). Tabs were notched out of the metal to hold the rubber mounting pieces for each device. Once I move the rear brake reservoir, this will clear up space for my seat frame modification.
- (Done) Sissybar-mount license plate & taillight – For a while I ran a side-mount license plate. I actually hate side-mount plates, but at that point in time I didn’t have the rear frame section attached to the bike and needed to get my earbleed fix. The new mount is pretty simple. Just a flat steel plate welded between the two tubes of the sissybar. Light is bolted to it. The license plate is elegantly zip-tied, because the screw-hole width on the plate is a little too wide. Who knows, I might redo the rear frame section to tidy it up.
- Relocate the rear brake caliper. The Goldwing has a very functional but cosmetically horrible way of mounting the rear brake caliper. There’s a wedge-shaped plate that mounts to the axle and the left suspension mount that covers about 1/4 of the wheel. The caliper mounts on the top-rear of this huge, ugly plate. I’d like to put the caliper under the swingarm, if I can provide enough support to mount it there.
- Fender – I need to come up with some kind of fender to stop splash-up. It’ll probably be JUST long enough to stop the splatter and mount the tail light and license plate.
Tank:
- (Arrived, needs modification) The stock tank just sucks. After doing a lot of research I decided on a 1987-1994 Shadow 1100 tank… Here is a picture of the same style tank. It has MUCH nicer curves than the ’96+ tanks. Its capacity is 5.0 gallons, over a half-gallon more than stock! It looks GREAT on the bike but it’s got a big problem…. the stock petcock location lands RIGHT on top of the left main frame rail. I’m going to build an extension that sticks inwards from the side of the tank (where the CB’s stock petcock was) and re-weld it in there. That should be an interesting bit of work.
- I’ll be repairing and painting the tank myself in flat-black most likely, then clearcoated. I might get creative and do something strange like silver decals covered by red clearcoat, but at this point I’m far from making a decision.
Exhaust:
- The bike came with a very rusty Mac 4-1 setup. I took off the can and fitted a downturned tip onto the header for a little while. It sounded like unholy hell and scared the crap out of anyone who hears me rev it up past 4000 RPM.
- (Done) I pulled a beautiful set of ’93 Nighthawk 750 exhaust pipes off a bike in a junkyard. The airflow characteristics of the header tubes are almost exactly what I was going to have custom fabricated! I’ve cut the downtubes just before the 4-2 junctions, so basically they come down the front of the bike, turn to point toward the rear, and stop before they get to the oil pan. I have the downtubes criss-crossed, so cylinders 1 and 2 make an X and cylinders 3 and 4 make an X. It looks really good, leaves tons of room for accessing the oil filter and drain bolt, and leaves the most ground clearance (which isn’t saying much!). And yes, they DEFINITELY blow fire.
- Lengthen the exhaust pipes. Now that the kickstand is out of the way, it’s fair game. I got 16 feet of 1-3/8″ OD steel tubing, now I just need to chop it up, bend it and weld it into place.
