009 Steves yellow and Black CB750/4...

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Prof
Founder, Choppers Australia
Posts: 5904
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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009 Steves yellow and Black CB750/4...

Post by Prof » Wed Jun 16, 2010 11:26 pm

you've seen this pic on one of the other Chopper Shed threads.
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Since this time Steve has gotten the bike together and painted and brought it down here for forwards, ignition switch mount, plus I offered to do up a rear guard late 70's style for him to try out... and we might have a go at a set of 4-2's as his drag pipes hang very low.


Here's just a couple of forwards pics. Lever parts pre assembly... right lever and top pieces make up the brake and the rest are for the gear lever. All in stainless.
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Gear lever completed. Foot rubbers are handle bar rubbers...
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Brake lever. Split steel increases 7/8" diameter so throttle grip can be used.
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Ignition switch and starter button hide behind left side cover in a stainless box.
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Rear guard fabricated from mild steel sheet... similar style was popular with US digger styles of mid to late 70's and 80's
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Taillight is a Universal Lucas style. Forgot to predrill the number plate holes!
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Last edited by Prof on Mon Oct 18, 2010 11:56 pm, edited 1 time in total.
Chopit'nrideit... Prof

Prof
Founder, Choppers Australia
Posts: 5904
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
Contact:

Post by Prof » Mon Jun 28, 2010 8:55 pm

Steve came to collect his bike on Friday. Liked the rear guard, forwards and pipes....

A better pic of the rear guard. Number plate/light section is form 3mm mild steel. Guard section is lighter gauge. Very very strong. Uses original Honda mounting bolts. A piece of auto brake line is welded inside the guard to carry the wiring...
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Rear brake treatment. Rear brake is cable operated (using a heavy duty Harley FX clutch cable).threaded end is a stainless steel yacht fitting (1/4 UNF) swaged onto the end of the cable... allows for a lot of adjustment. A hand operated hydraulic swaging press is readily available. Think mine cost $120. Outer cable is retained by a stainless bracket using brake anchor bolt. A 3mm roll pin stops it from swivelling under pressure. Adjusing nut on end of cable was turned form aluminium in lathe. After a bit of practice I've gotten the time to make them down to 17minutes each when doing foru at a time!. Thread only goes half way through. Remainder is drilled slightly larger.
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Pipes...
Steve has drag pipes but they hang under the bike and restrict ground clearance... and he wanted to use lowering blocks to drop the rear of the bike. I said I'd have go at some 4-2's ... and if he didn't like them I would use them on another bike.
Here are two pics of themfinished and on the bike. headers pipes are mild steel which he will paint black. Collectors are made form 2.5" stainless, bent at 30 degrees and tehn trimmed close to the straight section for the turnout effect.
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My more recent forays into pipe making, use prebent mandrel bent pipe. You can get them in virtually any size from about 1" to 3" and beyond. PC gave me some good advice when I started.

Here the two left headers are welded up out of four pieces each. Right ones ready to start. The ends of the headers that bolt to the head have been expanded by the pipe bending folks to fit the Honda manifolds.
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On these pipes I used all 90 degree bends. They were perfect for the first bend, but the second bend was slightly more; achieved by cuttting and joining part way into the bend. Downside of this is that bending shrinks the pipe slightly so a couple of cuts are needed so the straight section can compressed slightly with a hammer to match up. This could also be done without the cuts by heating with the oxy... time consuming when having to charge for your time. Welds are done with a MIG. could also be done with small arc rods or fusion welding with oxy. Set welder up for full penetration through the metal... protrudes about 1mm into inside of pipe. You can also see that pipe ends are chamfered 45 degrees so the is a full thickness weld once pipes have been linished back.
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Collectors are of stainless. Two pipes for each collector are mounted on a simple jig to maintian correct spacing and allow me to cut and shut the inner pipe into the header.
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When joining pipes, weld them on the inside to get a complete seal. Then outside that will be seen can be welded to allow a nice finish...
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The 2.5" collectors were squashed in a vice. The opening is left slightly larger than the 1 5/8" pipes. The resulting width then dictated how much the two pipes needed to be "siamesed" to match the header. Once the sides have been welded as seen here, the collector can be hammered in to match the slight courve of the two joined pipes. Once polished the jion will not be seen... just nice smooth curves.
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Two views of the collectors ready for polishing. The brackets are made from 5mm stainless. Anything thinner, whether mild steel or stainless is likely to crack eventually so play safe. Care has been taken in their design to ensure they are welded to the collector on two facets (weld goes around each corner in this case) to prevent cracking of the thinnner collector tube along the weld
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The headers enter them at a 45 degree angle. this is to keep theright side narrow enoughto clear the kick start.
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On the left side, the gear lever curves out over the pipes.
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So there you go, with mandrel bends and a bit of patience you can knock up a pretty nice set of pipes.
Chopit'nrideit... Prof

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