WARNING:-
Brake linings may contain asbestos. Take care especially when working on the rear drum brake, the dust can collect in here. As with aerosol painting use a high quality face mask.
Tips:-
Pump out the caliper piston before draining the hydraulic fluid from the system if replacing pads or servicing the piston/seal.
Replace the bleed nipple with a stainless replacement (Inox Fasteners). Note: the Honda bleed nipple is non-standard, being 2.25mm longer than normal. To remove a corroded/seized nipple soak in releasing fluid for days and apply lots of heat. Should the nipple still refuse to move or snap off spark erosion is the only answer try SEP-Kegworth
EBC 'Kevlar' pads are the best available for this bike. These have a coating on the outer edge of the pad that may foul the cylinder, some fettling may be required.
Fit Earls stainless steel braided hoses, these don't swell under pressure and therefore give more power to the slave cylinder. Available in kit form from Inox Fasteners- state whether you want to keep the bottom rigid pipe or not.
Known problems:-
Make sure the front calliper pivot is free to move. Do this by loosening the adjusting screw and pushing the calliper toward the wheel. It should move freely about its pivot arm, if not.... The front calliper support bar has a pin running through it, attached by a stud and a nut at the bottom. Water gets between the pin and bar and causes corrosion, seizing the pin to the bar. Remove, clean and grease the pin (heat may be needed). There is also a sealing o-ring at the bottom of the pin. Fit a slightly oversize o-ring to give a better seal and stop the water entering. Use a high quality synthetic grease like 'Super Lube' when re-assembling, NOT copper based types.
The calliper piston can seize causing the brake to stick on and run hot or stick off and not work at all!! Remove the piston and seal. Thoroughly clean the piston and cylinder, especially the seat for the seal. NEVER use anything made from steel i.e. wire wool, try scotchbrite (pan scrubbers) or anything stainless steel. NOTE: The seal is usually re-useable. Assemble the calliper using brake fluid as a lubricant, the piston should now push home by hand.
These early ohc fours were fitted with stainless steel discs making wet breaking a problem. There is only one powered piston calliper and not a large contact area for the pads - take extra care in the wet. Classic Motorcycle Mechanics Guru Graham Curtis recommends that only Silicone DOT5 brake fluid be used after first thoroughly cleaning all traces of old fluid from the braking system. This has the advantage of not absorbing water like other fluids from the atmosphere (every time you open the reservoir to check the level). Disadvantages are a lower boiling point which may be a problem if the bike is ridden very hard. Hydraulic systems will continually collect water from the seals etc. and therefore the brakes must be bled regularly to remove this from any low points in the system.
Brake noise can be a problem. Clean the rotor thoroughly, first and easiest job. If that fails remove the brake pads clean the rear of each pad and use fresh anti squeal grease on the back of each (NOT THE PAD ITSELF) then reassemble. If the pads have worn enough so that the bevelled edge is now flat, sanding the pad edges to make a fresh bevel may also help, DO NOT however remove the red wear indicator when doing so, if either pad is that worn - replace them. Also make sure the pads are aligned correctly by loosening the retaining bolts, hold the brake on full and then re-tighten with the brake still on.
Dirty brake fluid in the master cylinder indicates the need for a clean and re-build. A parts kit is still available for this in 2004.
Wheels
The spacer (with central groove) goes against the brake plate, the plain (shorter of the two) goes next to the sprocket. The inner diameter is 17mm, outer 30mm. Lengths are approx 33.5mm and 29.5mm.
I balanced the wheels, the front wheel was spot on but the rear required a 42g weight opposite the valve. Weights are not easily found for spoke wheels these days and you may have to use the stick on type intended for cast wheels. UK riders try Joe Hughes International for a screw on balance weight in 26g and 42g weights, around £4.00 each in 2004. Although expensive they look good and are re-usable. The old lead (cheap) weights are now illegal in EU countries.
Tip:-
Before replating the rear axle and swinging arm pivot bolts, I used a lathe to centre mark each end with a small dimple. This I use as a reference when aligning the back wheel, Hondas markings are not that accurate and are difficult to see anyway after powder coating the frame. A pair of callipers can now be used to measure both sides for perfect alignment giving best possible machine handling and maximum tyre, chain and sprocket life.