Which year is this bike? How many miles are on the odometer? Will you be able to ride it? Unless he is willing to remove the final drive, you won't know the condition of the rear splines. You won't know the condition of the transmission input splines either. This part of the sale is faith-based unless you're a trained interrogator. You won't be able to see much of the tank's condition if it is full of fuel. You won't see much of the tank's condition through the flapper in the filler hole either. The cap assembly would need to be removed—four screws.
Questions that need answers by observation:
• Does the oil pressure light shut off when the bike is started?
• Does the charging light shut off and stay off after the engine is revved and while it's idling?
• Does the engine idle smoothly at around 1000 rpm?
• Is the speedometer illumination working? That will be challenging to determine. You'd need your head and the instrument cluster in a dark sack together. Have the owner take a photo if you do that, then post it here.
• Can you see coolant in the coolant reservoir gauge? It should be above Min and below Max when the engine is cold.
• Does the tachometer work smoothly?
• Does the speedometer work smoothly?
• Can you see the oil level in the sight glass a few minutes after the engine has stopped running?
• Find the oil/coolant pump's weep hole. Is it damp with oil or coolant?
• Find the weep hole at the joint between the transmission and engine. Any drips there? Transmission fluid smells like sulphur. If it's wet, eventually you'll be replacing seals or o-rings.
• How old are the tires? Find the date code on the tires. Older than five years should be replaced so that's a bargaining point.
Questions to ask the seller:
• "Can we let it idle until the fan turns on? In San Diego, that probably should be 15 minutes or less. It will turn on or else hot ccoolant will be eventually discharged from the coolant reservoir. You'll want that fan to turn on during this inspection; otherwise, you'll need to determine why it isn't working. The engine fan might be seized and need to be replaced. If the temperature light is lit before the fan starts, that's another problem. That could mean a new fan, a new coolant temperature sensor, maybe replacement relays.
• "New or used driveshaft?" If new, "how much did it cost?" $350 new in New Hampshire
• "What type of spline lube did you use?" "Will you be needing it or can you include it with the sale?"
Keep in mind that buying this motorcycle isn't important. :giggles