Hi all, looking to purchase a 906, what needs checking to confirm that it's a great bike not a dog?

check
- service history (last belt change, valve adjustment, fork oil/brake fluid change, steering bearings greased, brake disc and pad thickness, sprockets & chain condition & wear etc)
- for coolant or oil leaks on engine (ie output shaft), forks & shock as for leaks/cracks of the coolant reservoir.
- How old do the dust seals of the fork look ? Are they dry and full of fine cracks ? If the fork spills or the slider tube feels oily check for chips in the chrome. If the fork is hard and non responsive it probably wasn`t serviced for a while
- overall condition, stress cracks in fairings/ rear light cover, paint job (original? are all decals covered by clearcoat?), rust on frame, clearcoat of rims (oxidation) etc
- if you can remove the fairings, at least a rear one so you can see the rear cylinder
- Scratches on the mirrors, less well fitting FAR replacement mirrors or small dents in the tank from the steering or scratches on the outside of the steering halfs can indicate that the bike fell over or had a crash. Hence look closely at the steering stops on the steering tube of the frame (above the lower triple tree). Are there any cracks or are they bent ? If they are bent the steering will touch the tank when turned fully in or a longer adjustment screw was used. Check also if the outer side of the footpegs and rear brake/shift lever are scratched or bent
- look if the color of the paint matches on all parts. Orange skin surface will indicate respray
- the engine should idle and run well and not smoke. If you can do a compression test.
- you should be able to shift and find neutral position with no problems
- the clutch should not rattle too much and there shouldn`t be any squealing noises when the clutch lever is pulled (when engine is running that is)
- check the right swingarm side for white/acid spots. If there are the battery spilled acid which it will do if it boils mostly due to a failing regulator/rectifier
- does the clock work ?
- does the bike start well and do the lights brighten and dim if you open and close throttle? If they do the electrics may need some checking
- does the shock work or does it feel soft and bouncy?
- if it stood outside for longer the original exhaust tends to start to get surface rust, specially on the inner/swingarm side and around the welds
- does the ignition switch/key turn with no big effort or does it feel notchy ?
- does the clear instrument cover have cracks or are its clips broken off (which you`ll probably won`t be able to see)
- if there`s little fuel in the tank try to look inside if you see some rust. Check the front edges of the tank and the area around the fuel filler cap for rust/ bubbles in paint
- age and condition of original Michelin tires is not a concern as they will be so old that you`ll need to replace them anyway

If you buy it I personally would check even closer and do all the work of which I don`t know if it was done or not before just getting on it and drive. Be sure all maintainance work was done.
- check all electrical connectors for oxidation or melted connectors/wires. Clean all ground connections
- if that`s done and the regulator is checked for proper function, measure the voltage at the coils. If you measure a voltage drop adding a relay will improve starting and idling. It will also take stress from your ignition switch
- grease steering and swingarm bearings. Wheels should turn freely and w/o (bearing) noises
- check/replace worn starter brushes
- replace rubber vibration dampers under instrument panel wich are most likely broken
- if the headlight is dim and you can`t properly see the reflector clean it ( http://tinyurl.com/39yqszj ). Then measure voltage at the headlight. If it`s less than 12V+ and cleaning all connections won`t solve it add a relay also here (Lo and Hi beam will require a seperate one)
- check fork, swingarm, shock play
- be sure the ground connection to the regulator/rectifier is good
- a stripe of clear self adhesive tank protection foil on the inner side of the fork legs will prevent getting scratches from the brake discs when removing or mounting the wheel
- replace cables for ground, battery and starter with thicker ones (10mm², less voltage drop will improve starting power)
- if using a standard battery get a battery acid overflow tank (costs only a few $ and will save your swingarm from acid spots) ie http://tinyurl.com/3676z97
The more you do at the beginning, the less surprises you`ll have later on.

Some things may be more important to check than others, this is just as it came to my mind.

G.

Thanks, that's great! Let you how it goes.

I would add:
- check the pipes which are very prone to get rusty, at least in the inner side;
- check for the notches on the swingarm: when the bike falls down, often the rear footpegs go back to the swingarm, so that it goes notched (I hate that...).
Ciao

bent and cracked steering stop with new/longer screw to compensate