Documents
There are few documents which are most important
Government registration certificate - The
details of this certificate should match with the basic configurations
and the details of the vehicle such like engine serial number, chassis
serial number, chassis color and etc..
Last annual registration license and annual insurance - It is better if you can obtain the last copies available or it won't be easy to attain new copies if those had lost. The annual insurance is not much essential but my opinion is to reject the vehicle that sells without last annual registration license.
Transfer paper copies - If the vehicle had been transferred among few people it good to collect the user's copies of transfer papers. (Ask for NIC copies if available for your own safety)
Performance
Engine
There are some basic but much important things you should check. First switch on, check whether it is on idle or not, put the transmission to idle, then start it... you may feel hard to listen to the engine sound with the noise of exhaust.. ok.. the trick is cover up the exhaust end with your hand.. its not too much hot yet.. so go on.. cover it up till you clearly here the sound of engine...
Now you need to concentrate your mind on just the engine.. you may find the RPM of engine clearly.. now listen more... in the inside of the top of the bore..(tappet valve cover/ rocker box).. check if you can hear some abnormal sound comes out the speed of twice of RPM? like metals hitting together rapidly? This happened normally when valves and rocker arms had worn out.. Now listen to the sound comes out of the bottom of the bore.. Inside from the crank case.. some abnormal sound accordingly to the RPM.. slowly.. If u heard that, it is the sound of crank rod or the sound of crank bearings.. those had worn out.. you need to go for a engine repair.. If you can found a rubbing noise from the left side of the bore.. it should be the sound comes from timing chain but it is somewhat hard to hear.. so you need to practice this with another bike before you are going to inspect the bike that you are going to purchase..
Now you have to check the exhaust gas for its color.. so go on and accelerate the bike to max RPM and check the exhaust gas color.. if you find it comes white.. bore has worn out so you have to replace the bore, piston and piston rings etc.. If you found that color as black.. it should be an error of carburetor adjustments, dirty fuel.. or may be the low electricity supply for the ignition plug.. but before you are going to check the electricity check the condition of clutch plates.. simple get on to the bike.. retract the main stand and squeeze the clutch handle.. put the transmission in to 1st and slowly release clutch while accelerating slowly.. if you need to release the clutch a small distance clutch plates are good.. but if it is required to release more to engage clutch, that means clutch plates have to be replaced..
so now switch off and stop the engine.. you need to remove the power adapter of ignition plug and get the wire out of the adapter by slowly rotating to disengage.. now you need to get that wire end to the engine cover.. or anywhere of chassis but don't let the wire to touch the engine.. please keep remember do not handle the wire with some distance about 6 cm from the open edge or you will get the electric shock grounded though your body.. keep the open edge 3 or 4 mm close to the chassis or engine cover and hit the starter button (or kick the engine) and you will notice that sparks comes out.. it this spark is strong with bluish yellow color engine electrical system is better or it is weak as spark comes with yellow and so weakly.. you need to repair the coil pack or the ignition coil of the bike..
Condition of other parts
Engine oil seals
You need to check for leakages of engine oil seals..inspect at the transmission pedal, kick pedal, exhaust manifold, around the bore and the lower side of the engine for any signs of leakages..
Fork oil seals
You need to check for leakages of fork oil seals.. if they have been covered up with rubber covers simply remove the clamp to inspect.. you can see any leakages persists.. push the forks downward by applying front brakes and pushing handle downward.. so you can see whether any of fork oil comes out through the seals..
Fuel tank
Inspect inside of the fuel tank by opening the filler cap for any sign of corrosion and the bottom edges of the tank for marks of cracks, paint removed patches, corrosion, fuel leakages and for any welded or sealant applications. Tank is much expensive and less repairable so you need to pay more attention always.
Rim and hub
Another common fault of old bikes is cracks on hubs and damaged or cracked rims. These things should visually check with care to get more value for you money and to prevent after repairs of purchasing. So its all up to you..
Test riding
You must ask from owner for a small test ride as it is the most important part
This comes with experience so how ever you need to go for that...check followings..
1. Vibrations you feel at idle due to loosen parts of the bike or due to a fault of engine
2. Smoothness of transmission shifting
3. Comfort of the ride
4. Condition of brakes
5. Condition of the shock absorbers
6. Any vibration of handle cup set.. or hub cracks may caused to sudden heavy vibrations
7. Acceleration of engine.. check whether any misses occur when accelerating the engine
8. Accelerate suddenly to higher speed and let the engine to decelerate by itself by applying clutch so you can find if any back fires occurring due to any available carbon deposits on exhaust manifold or by over fueling conditions..
* Finally please comment if there are any mistakes i have made or if there's any thing should be added to the post.. I don't want to argue as I'm posting this article with my knowledge and experience.. I'm always willing to correct myself with new advises..
