What should I look for when looking at an older GS500? I'm trying to become a grease monkey but I would need to have a bike first.

Normally here are the things I look at.

Hooks on the Sprockets,
condition of Chain, cleanliness, rust, tension
Tires, (cracked? unusually flat in the rear tire. no longer a ")" but a "]"
Any damage on the front forks
any oil leaks.
color of break oil?
Damage on frame and overall condition of the bike and the attitude/style of the owner.
title

I normally don't test ride bikes because I don't want to accidentally drop it due to my lack of skills or some strange issue that the owner didn't tell me. Rather I have the person do a couple loops on the bike and try to listen to any engine abnormalities.

am i missing anything else? what do you do when you look at older used bikes?

Copying this from one of my posts elsewhere, but it's all relevant.

Things to look for: Check the compression in both cylinders. You can pick up a cheap compression tester from Harbour Freight. You'll need a 12mm sparkplug thread adapter for it to fit. If the compression is low, walk away. Good compression is ~140psi with the throttle wide open. Check that the front sprocket shaft hasn't been broken. If it has, it will be welded on. Walk away. Ask him not to start it prior to you showing up, you want to start it cold and see how it starts. Give it a try with no choke when you show up and if it starts, he had it going before you showed up and could be hiding something. GS's are extremely cold blooded (because they run lean) and generally require full choke to start if it hasn't been running recently. Once you have it running, keep track of how long it takes to go from full choke to zero choke. It should be less than 5 minutes if you're revving it at 3-4K rpm and once choke is off it should idle between 1300-2000 rpm depending where the idle screw is set. I keep mine at ~1700 rpm.

Heyooo,

http://www.clarity.net/~adam/buying-bike-content.html

a couple threads down.

Quote from: justinmc84 on May 29, 2011, 06:06:23 PM
Heyooo,

http://www.clarity.net/~adam/buying-bike-content.html

a couple threads down.

 

With the GS specifically, you want to know if the valves have been adjusted, esp on a bike with some mileage. A hot compression test will help - low compression can mean too tight valves. The factory spec is too close, and the valves don't hold their clearance very well. So, if it goes 20K without an adjustment, expect a sad top-end. Also check the condition of the front rotor - the single front brake disk takes some abuse. Check the oil level - the bike tends to burn some oil. You want to make sure the level is okay. Low is a sign of neglect.

Other than that, it's a pretty straightforward bike.

Quote from: jacob_ns on May 29, 2011, 04:20:25 PM
Copying this from one of my posts elsewhere, but it's all relevant.

Things to look for: Check the compression in both cylinders. You can pick up a cheap compression tester from Harbour Freight. You'll need a 12mm sparkplug thread adapter for it to fit. If the compression is low, walk away. Good compression is ~140psi with the throttle wide open. Check that the front sprocket shaft hasn't been broken. If it has, it will be welded on. Walk away. Ask him not to start it prior to you showing up, you want to start it cold and see how it starts. Give it a try with no choke when you show up and if it starts, he had it going before you showed up and could be hiding something. GS's are extremely cold blooded (because they run lean) and generally require full choke to start if it hasn't been running recently. Once you have it running, keep track of how long it takes to go from full choke to zero choke. It should be less than 5 minutes if you're revving it at 3-4K rpm and once choke is off it should idle between 1300-2000 rpm depending where the idle screw is set. I keep mine at ~1700 rpm.

Is there a walkthrough of how to check the compression. What about the sprocket shaft? Picture? Sorry I'm a total wrench noob. : /

PM sent but I'll repost here for posterity and for any corrections/additions people here might have. I'm nowhere's near an expert, I just read a lot to learn what I need to do.

Okay, first thing you'll need is one of these: A Compression tester. You'll need a 12mm adapter for it as well, that's the part that you screw into the sparkplug threading. I had a bit of trouble finding the 12mm adapter because it's kind of a weird size but eventually found one at my local NAPA Auto Parts for about $12. The compression tester was from Princess Auto (Harbour Freight kind of store) for around $20. It's just a cheap tester because I really won't need it often but I've seen compression testers for several hundred dollars.

Anyway, testing compression is really easy. The engine needs to be warm, not hot, so run it for about 5 minutes and then shut it off. Remove both sparkplugs with an 18mm deep socket and ground them to the engine block by just placing them on the block, still connected to the leads. Screw in your compression tester to one of your cylinders and make sure it's snug because you don't want any leaks (you are doing a pressure test). Open the throttle to full and hit your starter. Hold the starter until the pressure in the gauge stops climbing and mark down the pressure on a piece of paper. Purge the pressure from the line with the valve on the hose and repeat the test once more on the same cylinder for redundancy. Repeat the test on the other cylinder.

Below is an excerpt from the Haynes manual regarding the GS500 compression:
Standard: 142 to 199 psi (10 to 14 bar)
Minimum (both cylinders): 142 psi (10 bar)
Minimum (one cylinder): 114 psi (8 bar)
Maximum difference between cylinders: 28 psi (2 bar)

If you do your compression test and find it's low you can do a simple test to find out what your problem may be. Pour a tablespoon of oil in the offending cylinder and redo the test. If the pressure goes up it's indicative of worn piston rings. If the compression doesn't increase with the oil added it's pointing towards valves.

Once you're done, re-install both sparkplugs into their respective homes and you're done.

Thank you!!