GS500 Knocking

[Kyromatic]

So here's the breakdown:

I bought a 1999 GS500 a few months back, seemed to be running great minus some richness and oil problems (after researching online, they all seemed "typical" of a GS).
Two weeks ago, I suffered complete failure, ended up pushing my bike home. After some finagling, I managed to get it back on and there was a loud knocking noise. Terrified of it being a cam chain problem, or any number of things that could destroy my engine, I immediately turned it off and began researching.

I have poked around and have yet to find the problem.

IT IS NOT:
Cam chain (it is tense and not broken)
Valve clearance
Magneto
Counterbalance bearing
Nothing is in my exhaust

My bike wont start unless it is hooked up to jumper cables, and even then I get power loss. There are new spark plugs in it and the battery tests fine.

COULD BE:
The fabled "cam end float" but I can't find any solid info online
Connecting rod failure (I have my fingers crossed that this isn't the case)


Here's a video of the noise:
http://www.youtube.com/watch?v=fOYekbWuI0Y


Any help is MUCH appreciated. Thanks in advanced!

[adidasguy]

Can you tell us how you check the items you have ruled out?

Were you low on oil?

The fabled "cam end float" isn't much and is a little rattle at the top end. I think it is rarer than led to believe or not as serious as some make it out to be. There are different thicknesses of washers on the cams to make them run tight and smooth. Maybe serious cam noise is someone forgetting to put the washers in or swapped cams and had washers that were too thin. Can end float is just the cams sliding back and forth a few thousands of an inch and makes a little noise. Nothing that can prevent a motor from running.

Anyway, cam end float is not serious and is not what you have.

You might remove a spark plug and look in the cylinder. Those cheap $75 fiver optic snoop scopes are great (Harbor Freight). See if there is any damage to the top of the piston. If there is, then it is probably a broken valve. (But I though broken valves killed a motor).

What about the bolts holding the starter to the magnet rotor? They have been known to come loose. Did you remove the left cover and look at the magnet rotor and starter gear bolts?

Running rich is not common since the bikes are lean from the factory for US emissions standards.
Oil: Generally not an issue. Some older motors use up oil as the rings wear and the valve stem seals wear out. Most bikes use very little oil. Were you low on oil?

[Kyromatic]

Thanks for the response!

I was low, but not dangerously low. I have been keeping an eye on my levels since a buddy of mine said that GS's can be oil hogs. When the bike broke down, the oil light did flash on shortly before breaking down (within minutes) but did not stay on. I was planning on doing a full oil change before riding it that day, but an emergency came up and I had to leave before I could do the change. The shop I bought it from said they had done an oil change right before I bought it, I'm kicking myself for not doing one anyways. It has hardly been 1,000 miles since I bought the bike.

Here's exactly what I've done in more detail:
I manually turned the camchain with the crank shaft. Went full 360 a few times and checked every inch of the cam. I measured my valve clearances and they were within the correct specs from my manual. I have taken the entire exhaust pipe off and looked into the hole and did not see any damage. I did not check inside of the clutch basket when I opened that side up, because my main concern was the counterbalance bearing. I opened the magneto and everything seemed fine, but I did not check the tightness of each bolt, I can check that if you think that could be the problem.

I forgot to mention that there were some flecks (not chunks, more like very fine specks) of bronze/copper colored metal when I performed my oil change. This makes me think that it is some kind of piston problem, but I did not know how to check without tearing the whole engine apart. I will look into the spark plugs again, but I had not noticed any scoring or damage when I looked before.

Everything that I've opened and looked at seems to be well oiled and in great condition. I'm considering also replacing the battery to see if that could be part of the problems, but a failed conrod could explain my power loss and inability to start, right?

[Kyromatic]

Sorry for adding another question into the mix.. but.....

I found a 2004 GS500 with a busted magneto (was laid down). I was wondering how hard it'd be to replace it with mine, or if that was even possible (a 1999 and a 2004). They're willing to let it go for $150, and I am tempted to take that offer. I'm worried about fork damage, so I'd probably drop the engine into my bike and then use the spare stuff for parts.

THANKS AGAIN!

[Kyromatic]

You might remove a spark plug and look in the cylinder. Those cheap $75 fiver optic snoop scopes are great (Harbor Freight). See if there is any damage to the top of the piston. If there is, then it is probably a broken valve. (But I though broken valves killed a motor).

Here's two videos I just took of the pistons: valves:

http://www.youtube.com/watch?v=qZ5F5oYeE6A

http://www.youtube.com/watch?v=b2InsNf74n4

[gsJack]

No pistons in those vids, those are views into the ports looking at the valves.  At least those 2 valves aren't broken.

[Kyromatic]

Well, that was a fail on my part.. I guess I'll invest in that scope you mentioned.

[adidasguy]

Not a fail. It was a good way to look. You have to remove the carbs to see the intakes. Looking in through the intakes might give good info. At least it can help rule out the problems.

The oil light blinking on indicates you were low on oil. That could be bad. Had you checked oil levels and added more oil as it went down?
Bits of copper doesn't sound good. No copper in the bike but hot destroyed bearings can have a copper color from the heat.

From what I've read, I'd place my bet on a crank bearing.

You can swap magnetos. You also will need to swap the timing  pick up on the right side. I would wonder what other damage could have happened to the motor if the left side was so damaged. On the plus side: for $150 you can make more than that back by selling off as parts. A good engine head alone can go for $150. If the frame is straight and has a title, that's worth money. Lots of money can be made parting out a $150 bike. Get it and part it out! make some cash!

I have one similar to this. Bought it at Costco. They are handy for more than just bikes. Looking in holes in walls, in a pipe, up your nose (gross!) and places best not mentioned (no - I didn't. Just using my imagination as what the Ausies might do with one of these.)
http://www.harborfreight.com/digital-inspection-camera-67979.html



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[Joolstacho]

Sorry for adding another question into the mix.. but.....

I found a 2004 GS500 with a busted magneto (was laid down). I was wondering how hard it'd be to replace it with mine, or if that was even possible (a 1999 and a 2004). They're willing to let it go for $150, and I am tempted to take that offer. I'm worried about fork damage, so I'd probably drop the engine into my bike and then use the spare stuff for parts.

THANKS AGAIN!

I've just been mixing and matching magneto parts from an '89 and an '07. They do interchange, but the 07 stator is slimmer than the 89 by about 4mm meaning that it sits back in the casing a little. From my measurements it still aligns with the rotor okay but I don't know if it will affect ACV output yet as I'm still testing.
Have you checked your starter clutch? (mounted between the rotor and starter driven gear?) Mine was loose and making a nasty clattering sound, probably knocking against the rotor, possibly interfering with ACV output.

[The Buddha]

Oil light - I've seen it light for less than a few seconds before the motor was dead. The oil light is a pressure switch. It lighting up = pump is dead = no oil pressure to crank.
Cool.
Buddha.

[sledge]

Bearing shells are essentially a sandwich made from copper, steel and white metal 



From the sound of it somewhere in there you have a bearing that's worn the white metal (Americans call it babbit) away and is now down to the copper......see the drawing.

[The Buddha]

Sorry for adding another question into the mix.. but.....

I found a 2004 GS500 with a busted magneto (was laid down). I was wondering how hard it'd be to replace it with mine, or if that was even possible (a 1999 and a 2004). They're willing to let it go for $150, and I am tempted to take that offer. I'm worried about fork damage, so I'd probably drop the engine into my bike and then use the spare stuff for parts.

THANKS AGAIN!

Put that motor in yours, or better yet, put your alternator in it and rebuild it.
Cool.
Buddha.

[Ron888]

Lots of great help here

Just a quick query - maybe you should take to a mechanic and get an opinion.It could possibly be something bizarre like a faulty/mangled starter motor...?

[adidasguy]

Lots of great help here

Just a quick query - maybe you should take to a mechanic and get an opinion.It could possibly be something bizarre like a faulty/mangled starter motor...?

Starter motor is disengaged due to the one-way mechanical clutch on the starter gear. Starter motor does nothing once bike is running. So that can't cause the noise.
Bad bearing could cause excessive drag when starting the bike as well as the knocking sound. Starter motor could now be going bad due to the other problems, but starter motor is not the cause.

Metal came out when draining oil - right? I'd say drop the bottom oil pan and see what else is there. The shards of metal will let forensics determine where the metal came from.

I still vote for bad crank bearing. Drop the oil pan and let's see what is there.

[sledge]

You are going to find something that looks like this.....

[yamahonkawazuki]

You are going to find something that looks like this.....

I have a sinking feeling this is the case.  perhaps I overlooked it. but did you ( owner/OP)  poinpoint where the knocking was coming from?

[The Buddha]

Bad Counterbalancer bearing has my vote. The CB is about 2" above the crank, the thing may have had no oil pressure before the oil light came on ...
If your pump was working fine, you may have had a few loose bearings so you probably didn't lose much. if you blew the oil pump, very very unfortunate but well, that sorta crap happens.

Cool.
Buddha.

[Kyromatic]

Bad Counterbalancer bearing has my vote. The CB is about 2" above the crank, the thing may have had no oil pressure before the oil light came on ...

I already poked around in there. I didn't take it out (was worried about causing further damage) but I found one forum that said to wiggle it around and if it was loose, that was definitely the problem. Thing is, I couldn't get it to budge at all! Do you think I should go back in there and take the entire shaft out?

Thanks for all the replies! I won't be able to do anything to the bike tomorrow, maybe Thursday.

[Kyromatic]

Also! I have noticed a small oil leak out of my crank case in the last couple of days. Might be a faulty gasket? It's not enough to drain my bike of oil, but it could have caused my oil levels to unnoticeable drop over the few weeks I was out of town over the holiday.

yamahonkawazuki: It SEEMS like it's coming from where the pistons would be, but it could be radiating from somewhere else. I haven't used the ol' screwdriver test yet, because I couldn't get the bike to stay on for more than a few seconds let alone start most of the time. I'm also afraid of causing further damage if something is loose and banging around...

Have you checked your starter clutch? (mounted between the rotor and starter driven gear?) Mine was loose and making a nasty clattering sound, probably knocking against the rotor, possibly interfering with ACV output.

Would I just open it back up and check all of the bolts or do you want me to completely take it out?


THANKS!!

[Kyromatic]

You are going to find something that looks like this.....

What other bearings should I be checking? Like I said, I opened the crank case and tried to wiggle the counterbalance shaft, but it was pretty solid. I don't THINK the bearing is that bad, but it could still be in the early stages. Would you recommend me taking it out and checking the bearing? I can't find any solid info on how to take it out and put it back in. Feel like it would need to be torqued back down, and I don't want to mess the bike up even further by poking around in places I shouldn't be poking.