Buying a Used Motorcycle

by Flyboy (Road-Apples Member)

Since it makes more sense to buy a used bike as a newbie - like myself, here are a couple of things to look for:

Global

Is the bike clean? A person that can't be bothered to wash the bike they're selling is more likely to have been neglecting it in other ways.

Was the engine warm when you arrived to look at it? I read somewhere that some people might warm up the bike to hide the signs of engine problems.

Ask a seller if he/she would mind a test ride (bring a helmet with you). Offer him/her your car keys and/or credit card to hold onto as an insurance (some owners might simply be worried that you're going to take off with a bike). If he/she refuses, walk away. There's plenty of used bikes out there, you don't have to have this one (Harley lovers excluded – you simply have to get that one right there, and no other). If he/she agrees, ride it at different speeds and go trough all the gears several times. Listen for the engine.

How long ago was the ad posted? This might not necessarily be an indication of a lemon, but it could be. It’s possible that more keen-eyed shoppers have noticed what a piece of crap that bike is. Alternatively, an owner might be asking for too much $$$, but there’s nothing wrong with the bike itself. In any case, if the add has been out for several weeks and the bike hasn't been sold you can bet your ass the price won't be as stiff as it was when it was first posted. If you can't afford the wait of few weeks, start thumbing trough Buy and Sell earlier and circle a few to keep an eye on, or better yet, go to Craig's List. There you can see the date the ad has been posted.

The seller. Don't laugh, it has been proven that people more often than not are well judged based on their appearance/first impression. If you get that funny feeling about a guy/gal - you're probably right. Ask a lot of questions (it would be a good idea to write a whole list of questions to ask in person ahead of time). How they answer may be a clue as to whether they're lying to you or not. This one is straight from a top FBI polygraph examiner Jack Trimarco http://www.jacktrimarco.com/ : if a person repeats a direct and clear question you asked, they're almost certainly concealing something relevant to that question, and are buying time trying to come up with an answer.
Pay attention to what they're saying and how they're saying it, but most importantly what they're not saying and how they're not saying it.

Specific

Engine is too big a topic to cover, and I'm the least of an expert on this subject, so a mechanic is probably a good investment. But if you're still reading all this, you're probably interested about the things you can look for yourself. Like the color/level of the engine oil. Charcoal black is not your color, regardless of how well it matches the rest of the bike, your boots, helmet, gloves or any piece of gear you might decide to put on. Ask when it was that a person changed the oil last time. Do they have service records? If not, ask them who worked on their bike in the past. If it was themselves, they should be able to answer without hesitation what is the specific oil, chain lube, etc that they used. If it was the shop, they should be as fast to answer when asked for the name of the shop.
Also, look for oil on the engine casing, specifically around the seals as well as around the bottom of it. The seals should be clean and dry to touch. Dirt sticks to the oily areas so look for dirt on and around the engine.

Fork seals. This is one I never saw on my bike, and I should have. Is there oil below the seal(s) -again, look for dirt? It's not unusual to have a ring of dirt on the chrome above the seal; every time the front suspension compresses, a few molecules of oil that were between the seal and metal are being dragged outside, and will pile up at the highest compression point, collecting dirt. If the dirt rings aren’t present (use a flashlight if fairings are restricting your vision) and the bike isn't one of those that has that corrugated rubber protection that keeps the dirt out, it has most likely been wiped clean. Feel around for oil below the seals with your fingers. If the fork is leaving oily residue on your fingers at few inches below the seal - you likely have a problem.

Tires. This one is simple; can you see the wear marks the manufacturer builds into them? If they're flush with the surface of the tire - you're shopping for rubber (steer clear of Trojans, they're too slippery). Has it been worn flat in the middle? Look for anything that might be lodged in the tire. Minute specks of debris are common, bur bolts and nails sticking out of the tire won't give you the much needed traction, and I'm yet to see someone secure their bike by nailing it to the pavement.

Chain and sprockets work into each other over the time stretching the chain. While one can tighten the chain by moving the rear wheel backwards, that's doesn't address the sprocket. When chain is stretched, the distance between two studs at the ends of each link get pulled further apart. That means that a chain that is wound around the sprocket isn't pulling all its teeth, but only the top one, causing accelerated damage to the sprocket. The seller might have tightened the chain recently, but you can still feel for wear and tear and this is how you do it:

Pull with the chain with your fingers mid-point-rear on the sprocket. For most street-oriented motorcycles, when measured like this replacement is warranted when there’s around 1.5mm of movement - being able to pull the chain 1.5mm off the rear center of the rear sprocket. I got this info from http://www.motorcycleanchor.com/motorcycle/how_to/mc_chains.html, go check it out, it's all about chain and sprocket care.
Also, if you see any rust discoloration on the chain – that can’t be good. Modern chains have sealed lubricant inside the chain roller mechanism, and rust (and dirt) can damage the nitrile rubber seal causing the loss of inner lubricant. Yes, that’s bad. The higher the speed the more stress on the chain – hence the greater likelihood of it flinging apart. Try taking a chain to your leg when going 120Km down the highway. It might ruin your day, but it’ll make evenings around the campfire rather interesting.

Cables should be free of rust, frayed wires, water, dirt or any other contaminants. Pull the rubber protection off the handle(s) and peak inside while squeezing the handle all the way. You should see a 7x7 steel cable (7 bundles of seven strands wound together), and the fine coat of lubricant (usually felt on your fingertips), and nothing else.

‘Nuff from me, I’ll let others contribute. Or even correct me if I was wrong with anything said above