So I just bought a gs500 a week ago and I think I lost the lottery. I started noticing a knocking you can only hear if your right next to the motor. Didnt hear it when I looked at the bike before buying. Here is the noise: https://youtu.be/izg-WJP6HMk
Suspecting a balence shaft bearing or a starter clutch loose I took off the left side cover. Well that's when I discovered this :
https://youtu.be/COdX8Ec_wIc
I did confirm that the slop is in the crankshaft, as it can be seen in the signal generator on the other side.
So my question is, I'm correct in assuming this is a death sentence aren't I?
I am also wondering if I'm better off swapping the motor or if I should just cut my losses and try and sell this one and buy another. Money is really tight for me after purchasing this bike (got it for 1200), as I'm a college student. If anyone has any advice as to what my best and cheapest path is here that would be appreciated.
Note: I am mechanically inclined and can perform all the work I need to myself maybe short of a full on motor rebuild.
GSs are known for CAMshaft end float which creates that sound, but typically only when hot.
Take another listen to see if you can identify that the sound is indeed coming from the crankcase and not from the cylinder head.
If it's CAMshaft end float I don't think you have to worry that much. If it's CRANKshaft end float then I'm not sure where to go from there.
It's definitely easier (mechanically) to swap engines than rebuild, but it may be hard to find a good, cheap, donor motorcycle or a trustworthy engine out of bike. Rebuild, so long as you do the work yourself, is likely the cheapest option.
Either way you choose (rebuild, swap, replace) you'll be spending at least a few hundred.
It seems the noise was coming from the low end and as hence I took the cover off. That's when I discovered that I could move the crank in and out slightly and it made the sound seen in the video. I'm sure that's not normal and wanted to confirm that I was screwed.
The bottom end is f%&ked.
Service limit for crank float is about 0.15 mm.......its quoted in the service manual.
Most people agree that these engines are not worth the time and cost to rebuild and I doubt you will have access to the kit needed to do the job properly.....ie micrometers, DTI, plastiguage. But don't let me put you off, buy a manual, study it and make your own call
My opinion........take the cheapest and easiest option, find another engine and swap it out.
With you being a college student, I'd recommend looking for an engine with a roasted top end - probably cheaper than a complete / running motor.
Thanks for the replies guys. Does anyone know what year range motors I'm restricted to with my 2002 frame?
Quote from: Big Rich on May 29, 2017, 05:06:23 AM
With you being a college student, I'd recommend looking for an engine with a roasted top end - probably cheaper than a complete / running motor.
With the toasted bottom end at 17k miles I'm imagining the previous owner ran her with no oil at some point, I don't trust any part of this motor anymore.
Before I think about replacing the motor I wonder if I should tear it apart and see if I can just fix it by replacing the thrust bearing.
I am really curious about this question. Sometimes, engines can run with a lot of crankshaft end play. For example, my old air-cooled Volkswagen Beetle was way out of specs, but it ran thousands of miles that way and was still running great when I sold it. Of course it did not have a cam chain to worry about. Some two-strokes have cranks that float a certain amount, but they, of course, have ball bearings on the crankshaft. What does control crankshaft end play in a GS500 engine?
The gs has thrust bearings/washers to control the end play I according to parts diagrams. Which is why I'm wondering if it would be worth it for me to tear the engine down and just replace them. Problem is I assume that the crank would probly also need to be replaced and that would be more money than it would be worth. Maybe someone can chime in if just replacing the thrust bearing would be a feasible way to eliminate the problem.
Quote from: jamesf on May 29, 2017, 06:17:45 PMMaybe someone can chime in if just replacing the thrust bearing would be a feasible way to eliminate the problem.
Yeah.....I will, just give me a minute to look in my crystal ball and find my x-ray glasses :thumb:
Quote from: sledge on May 30, 2017, 12:02:34 AM
Quote from: jamesf on May 29, 2017, 06:17:45 PMMaybe someone can chime in if just replacing the thrust bearing would be a feasible way to eliminate the problem.
Yeah.....I will, just give me a minute to look in my crystal ball and find my x-ray glasses :thumb:
Good point, guess I wouldn't know till I was in there.