Head stock bearings wear at around 40,000 miles, replace with taper roller kit. Old bearing shells tap out quite easily with a mallet and soft metal drift unless they are already taper roller type. If so run a bead of weld to the old shell to allow you something to tap against.
Swinging arm bushes wear at up to 40,000 miles. If any play is felt at the rear wheel, an MOT test item – replace. These composite bushes are easily removed with a soft metal drift and hammer. If the replacement parts won’t push home with the palm of your hand, DO NOT knock in the replacements with a mallet as it may cause the composite material to crack. Use a length of studding and some large washers to just wind them in, turning the nut gradually with a spanner till seated. A large bench vice also makes a great press for these types of jobs. See also:- pattern parts
Wheel bearings, the retainers need special tools and therefore may need replacing at around 40,000 miles due to lack of lubrication. My bearing retainers were removed resulting in stripped threads. The two aluminium components welded together over years of neglect. These are not left-hand thread as someone told me at the time, so if they won’t move consider spark erosion or replacement hubs if they are available. Replacements are standard type front 2×6302, rear 1×6303 & 1×6304, do try to obtain the fully sealed type. Also do not forget to save the reducer from the sprocket side 6304 bearing.
Rear chain life depends on use/lubrication/cleaning routine etc. Around 6,000 miles is normal. I’m using RK heavy duty type, excellent with little adjustment needed. So far this chain has covered 12,000 miles and is still OK, it has been regularily cleaned and lubricated which is key to long life. O-ring replacement would require much less attention/cleaning/adjustment – however the pin length on most o-ring chains does not allow sufficient clearance to the engine crankcase, take care, I understand Reynolds may have a suitable type? MC-Again of Japan can supply a 520 o-ring conversion but is very expensive c£200.
Steering lock is often damaged from attempted theft. File the head off the retaining rivet, then use the key to remove old lock. In the event of the lock being snapped off in the locked position and no key available, carefully drill out the old lock. The new lock is held in place by a one way rivet and suitably sized washer.
Frame damage / corrosion is quite common around the side stand bracket. Clean up and re-weld as necessary. For extra strength consider a patch of mild steel tubing cut down the middle to give a ‘C’ section and weld over the damaged area.
All the chrome plated parts will benefit from some form of underseal, paying particular attention to any welded seams etc. I used Dinitrol rust prevention system, available from Frost Auto Restoration Techniques. I used 3125 to penetrate crevices followed by 4941underseal. A cheaper and more readilly available alternative is Hammerite Underbody Seal with added Waxoyl.
Powder coating in gloss black provides the best finish I know of after first shot blasting & inspecting the frame assembly.
Fuel tank often corrodes at its base near the welded bottom where water can collect. Most bikes will have had at least one replacement. Contact a specialist for repair, it is a dangerous pastime welding a fuel tank!
Removing dents from a tank can be difficult, one tip I overheard was to fill the tank with water and place in a chest freezer. The expanding ice will push out the dent. NOTE: It does require careful monitoring as it will destroy the tank if allowed to freeze too much. How long it takes for ice to form in 3.1 gallons of water is anybodies guess.
Removing the fuel tank involves unhooking the rear rubber strap and is not easy, maybe rheumatic hands or hardening of the 30+ year old rubber! A loop/strap could be fitted round the rubber giving something to get hold of. Do not use pliers as they will damage the rubber.
Stainless steel machined footrest/engine hanger as well as many other “machine specific” fixings are available from Inox Fasteners. Their web site has a wonderful technical section on stainless steel, worth a visit.
Exhaust system is short lived, around 20,000 miles is normal. Short journeys are the real killer but do make sure the drain hole near the collector box remains open. Some owners drill another drain hole at the lowest point of the collector (near pipe 1) to help with drainage.
Gear linkage rubber covers – These are not listed in the parts manual as a spare part. Good news, they are available under part number 24724-422-000. Bad news, they are difficult to fit. I greased the ball joint and thanks to the rubbers elasticity managed to slide them on. Below is another stainless replacement part, this time for the gear linkage.