Bad engine vibration after a long ride / I think I broke her. :(

[adidasguy]

2 weeks? That makes it seem worse.

Two places gas can get into oil:
1. Blown piston rings. Compression pushing gas down around the piston into thecrankcase
2. Bad valve / valve stem seals. Compression pushing gas through the valve stems into the head, which then drains down into you know where.

Then there could be a blown gasket. That would not cause that metal grinding sound.

Do a compression test
Take valve cover off and look at the top end for pools of gas.
There's some other test... having a blond moment.. is it a "leak down test"?

[oz353]

Check compression. May have blown a ring. That might have been the metal screeching sound. That would account for low power and gas getting into the oil.

+1

[Raydr]

I just want to clarify that the screech sound was a one time, 1/4 second thing. It hasn't happened since. Will check on the other recommendations.

[adidasguy]

Wouldn't a ring going out screech for a brief time while it is wedged between the piston and the cylinder wall then - well - its ground away? maybe same if a valve has something go bad?
The screech means its disintegrating. Once gone, no more screech.... just stuff leaking where it shouldn't go.
I think only a main bearing might continue to screech because they are big. A ring is a tiny, fragile thing that would disintegrate quickly.

[dropitlow88]

If a ring seizes to the cylinder wall then breaks free, depending on the severity of it, it can score the cylinder walls, break the ring lands, break the ring, rip the gudgeon pin right out of the piston, etc. in all cases the engine will run very poorly if at all and smoke like a cheap prostitute.

[Raydr]

The deepest I've been into the engine is a valve clearance check, so a lot of this is new to me. On the ride home, she actually seemed to run normally except for the vibration issue. Of course, I didn't push her hard. Would a bad ring cause the vibration?

[dropitlow88]

The deepest I've been into the engine is a valve clearance check, so a lot of this is new to me. On the ride home, she actually seemed to run normally except for the vibration issue. Of course, I didn't push her hard. Would a bad ring cause the vibration?

not normally, no. bad rings cause little/no compression and oil consumption.

[Kijona]

If a ring seizes to the cylinder wall then breaks free, depending on the severity of it, it can score the cylinder walls, break the ring lands, break the ring, rip the gudgeon pin right out of the piston, etc. in all cases the engine will run very poorly if at all and smoke like a cheap prostitute.

Not to mention make a TON of racket that doesn't sound like "normal noisy GS motor".

As far as gas getting into the oil...of course it can. Remember the guy not too long ago whose GS puked oil all over the place? I'm pretty sure that was caused by running on only one cylinder for a long time.

Check the squid-head looking attachment on the large tube that's off to the right side of the bike next to the rear brake lever. It will likely be wet...but see what's coming out of it. Check to see if it smells heavily of gas.

Needless to say...you need to change the oil asap. If nothing else, you can do a preliminary check to see if there's any metal in it.

You'd know if the ring had bit the dust. I doubt the motor would be running at all, honestly. Especially would not "appear to run normally" with bits of metal flying all over the place.

The vibration could just be caused by one plug being more severely fouled than the other causing one cylinder to fire stronger than the other.

[dropitlow88]

There are already fine particles of metal in the oil. The only way to really find the damage would be a complete tear down. Ten to one says the bearings are excessively worn.

[Raydr]

Just got done flushing with a couple of oil changes. Went to replaces the plugs and realized I must've left them with the cashier. Will replace the plugs and update. Last thing to check before going deeper I guess.

[Kijona]

Did you check the oil filter?

Not to argue but if a bearing came apart or something drastic happened to the motor, you'd see the metal in the oil filter/oil pan.

Also, what do you mean? Microscopic bits of metal, sure. You shouldn't be seeing anything in the oil if your motor is okay, though.

[Raydr]

The vibration could just be caused by one plug being more severely fouled than the other causing one cylinder to fire stronger than the other.

I was REALLY hoping this was the case. Alas, I swapped out the plugs with new ones (old ones looked a little fouled but not horrible) and same result. She is actually running normal at this point (starts/idles fine, normal amount of power, etc) but there's still the vibration.

Where do I go at this point? Compression test?

Funny enough, when I got home one of the rear turn signal stalks was hanging off. The vibration loosened an already loose nut I guess.

[The Buddha]

Vibration ... and runs fine after that screech, and you dont have goats ...
I'd ignore it.
If its what I think it can be, you're dead in a short amount of time anyway. This = counter balancer bearing. Its a full on rebuild anyway if it is that.
If its not, you can ride it forever and not even make any difference. You think you could have an out of balance carb ?

I dont think 1 cyl being low on compression will let it run fine. It would have all the power of a wet fart. Why ... cos one cyl is driving the oher cyl and the rest of the bike.

You got gas instead of oil and rode it WOT for 25 mins. It points to the cb bearing if not the main bearing, and a main bearing it would run for precisely 5 mins before it will die with massive banging noises. The CB is more prone to silent creeping failure.

Cool.
Buddha.

[Twisted]

Is the vibration happening only when the bike is moving or does it still happen when you rev it up at idle?

[Raydr]

If its what I think it can be, you're dead in a short amount of time anyway. This = counter balancer bearing. Its a full on rebuild anyway if it is that.

You got gas instead of oil and rode it WOT for 25 mins. It points to the cb bearing if not the main bearing, and a main bearing it would run for precisely 5 mins before it will die with massive banging noises. The CB is more prone to silent creeping failure.

Based on this and some other posts I read...I think this is probably it.

It sounds like I should not rely on her as my daily commuter, nor should I ride her long distance (e.g. to Austin from Dallas).

Any guesses on how much more riding I could get out of this bike?

I really don't have the time right now or in the foreseeable future to do a rebuild; I think it's time to consider selling her as a project bike to someone.

Major sadface. I was just talking today to someone about how even when I buy my next bike this year I'd keep her around.

I think she overheard and said "no way".

[Twisted]

Try and buy a donor engine if you don't have time for a rebuild. And sell yours as a project engine instead of a project bike.

[Kijona]

Someone bought a used GS (newer gen) motor for like 299 off ebay. That's pretty freakin' cheap.

[Raydr]

Just wanted to give another quick update:

A girlfriend was in town so we decided to go for some riding. We both agreed the vibration was just a little too much. We were able to still get some enjoyment by trying to maintain the RPMs in a range that didn't hurt/tickle too much. A couple of hours of riding later I decided that her last big job was going to be teaching this girl how to ride a bike.

The girl drives a stick so fortunately she already knew how to work a clutch. An hour in the parking lot and she was riding in first and second gear comfortably, making some wide turns and having a lot of fun. It was really windy and gusty and she handled it quite well.

It was getting dark so it was time to head home. She rode the bike up to me, and right as she stopped a gust of wind knocked her over and off the bike (the first and only time she went down.)

The bike kept running; I shut her off and assessed the damage: a few scratches on the left fairing, broken turn signal stalk, broken clutch handle.

I figured after all this we should just have a little fun, so we started her up, ran up and down the parking lot at high speed, and suddenly she died again.

She idles fine (with choke on and off) but if I give any gas she dies immediately.

I turned on the choke and used the high idle RPM to get us home. I lovingly parked her in the carport and there she will sit until I make a decision on what I'm going to do with her.

[5thAve]

For certain, a donor engine is the cheapest and fastest solution to your problems if you decide to keep her (bike, not the girl). You will recoup part of your cost by selling the blown engine here as a project engine. You will find plenty of takers. Replacing an engine in these bikes is fairly straight forward (and easiest if you have a 2nd pair of hands nearby to help with the job). Hand tools and a floor jack are all that is needed.

Good luck!