Possible valve knock and engine dying

[jrtaylorthird]

First post on here so first off - hello.

Now past the niceties. I've just recently bought a '92 500e from a supposed "bike tech" in Jacksonville, FL. Bike rode fine for about two days, he warned me about the famous cam chain noise and it really wasn't a problem, everything's stock except for a K&N Lunchbox, good chain, recently changed battery and tire check. 63k miles and pretty decent condition for a '92.

Now here's my issue. The second day after buying it, I was riding about 55 on the highway for about 20 minutes, when the engine started sputtering like it was running out of gas. It ended up dying after about 30 seconds of this, so I thought it was maybe bad spark plugs or a clog in the tank petcock. Something simple. I wait a couple of minutes, start it again and ride about a mile before the same thing happens but this time won't start. Engine won't turn, starter tries to spin and start but nothing happens.

Fast forward a couple of weeks. Now the engine turns over, idles really low, and makes a pretty loud knocking sound from what seems to be the left cam. Or at least the left side of the engine. If I try to rev it past 3000rpm it just won't, and trying to pull the throttle back too much causes the engine to die.

The previous owner told me he had done valve checks and usual "check-ups" etc., and he told me things were fine.

TL;DR help.

PS: This is my first bike and I don't really know too much except hours of video and studying of my Haynes manual. I can do basic mechanical work but nothing major.

[mr72]

Sounds to me like a bent valve, but could be something more or less serious. Hole in a piston, bent con rod, missing valve shim, jumped time, bad timing chain tensioner

[kapiteinkoek]

But... with hours of video and studying the manual you can do major mechanical work on a GS500 so no problems there I see 

Can you post a video with the sound on youtube or something?

[sledge]

63k?

Probably dropped a valve.

[jrtaylorthird]

For some awful reason this was posted at 240p. But here ya go.

https://www.youtube.com/watch?v=v3-m-z6jOYk

[crazydred]

I would say bottom end crankshaft bearing?
Just my guess

[jrtaylorthird]

Anyone know how much it would cost to just go to a shop and have them tell me what it could be? If I order the parts I'm almost 100% positive I could do the replacements/adjustments/fix-ups myself, it'd just take some more work.

But if I could figure it out without spending that money, I'd be stoked.

[mr72]

I have no idea what it would cost for a shop to do it, but it's free for you to investigate

Probably cost a lot for a shop to work it out. I'd say if you are going to a shop, I'd just pay for getting a top end engine rebuild and have them check the crank bearings and advise if they need to replace the as well. It's not going to cost a whole lot more to get it rebuilt than it is to get them to tear it down and tell you what's wrong then put it back together with the bad parts.

[crazydred]

He is right

[Edward Joesph]

I have a 2006 gs500F, when I purchased it the piston ring were seized on the pistons, at the time, I had just moved to this area I had no tools or time to work on it starting a new job. I had the top end rebuilt at a shop in my city. They replaced the pistons, ring all new valve and stems, cam chain tightener gaskets etc. It was $1100.00 when it was done

[mr72]

They replaced the pistons, ring all new valve and stems, cam chain tightener gaskets etc. It was $1100.00 when it was done

FWIW I bet you could get the head work done (valve seats, stem seals) for under $200 and with a micrometer, a ball hone, rings and a handful of gaskets and misc. you could have the top end rebuilt.

This is what I was suggesting to the OP... pull the valve cover and turn the motor over like you are doing a valve adjustment like this: http://gstwin.com/adjust_valves.htm . I doubt it'd take even a pretty beginner mechanic more than two hours to get that far. You'll be able to see if you've lost a valve shim or a retaining clip that way. If you've lost a retaining clip and you have parts everywhere under the valve cover it'll be very obvious. If the top end looks good then you just have to keep going. Pull the head, look at the valves, pull the cylinders, see the rings, pistons, rods, you can look down into the crankcase and get a look at the crank and etc. I think in a Saturday you could have it all torn down and know what was wrong, no matter what it is.

Problem is if you get this far then you're basically stuck going all the way on a DIY repair. And if it's a bad rod bearing or broken/bent rod then you're going to have to tear down the entire bottom end and you will have wished you pulled the engine first etc. And you need a garage and a bunch of workspace and a half dozen weekends to commit to it to get it back up and running, plus parts and waiting on the machine shop for whatever they have to do. It'll potentially be a whole lot cheaper ... I mean one of the gstwin guys reported recently (in a thread I read) rebuilding the engine for under $1K complete and that includes buying a NEW crankshaft which was over half of the parts cost. But it took two months' worth of weekends.

BTW that's a horrible noise but the bike's still idling at the right speed so I would be inclined to GUESS you might have a serious valve lash problem, like the exhaust valve is not opening very much on one cylinder, and the cam hitting the top of the valve is making that racket. You might ruin the cam running it but at least those parts are on the top! Start looking there. Problem might be staring you in the face.

[jrtaylorthird]

Took off the seat, tank, breather hose, and breather cover, only to realize the center bar of the frame below the tank prevents me from getting to the forward-most three nuts of the valve cover. Rear three were no problem, but I can't for the life of me reach those others up front. Any suggestions as to how to do it without removing the engine entirely?

[crazydred]

You can! With a torque wrench and a hex bit for example.
Place the wrench between the left fork and the frame to undo the front bolt.

Take the engine breather thing out first.
Take any cables out of the way.
The other two can be undone with the wrench under that frame bar.

[jrtaylorthird]

Alright, so a bit of an update. I got the cover off successfully, checked the valve clearances and they were all in spec.

Anyone have advice as to where I should go from here?

[jrtaylorthird]

Also I found what looked to be fibers or some kind of weird fuzz that was chunky but came apart when I pulled on it in different parts of the engine. I can't really describe what these are. Just grey, oily bits of fuzz. Almost like lint? I have no idea.

[jrtaylorthird]

SOOOO I think I may have found the problem. After taking the valve cover off and removing both shims (they were all in spec thankfully) and underneath the exhaust cam I found one of the washers on the camshaft proper had moved somehow, warped and scored the actual engine case. It got so distorted it kept rubbing against things inside probably causing the noise. Now I've got the thing taken apart, and (after accidentally dropping a washer into the engine and spending about two hours trying to successfully remove it) will put it back together tomorrow.

https://scontent-atl3-1.xx.fbcdn.net/v/t34.0-12/14281582_943328059127180_1772322799_n.jpg?oh=bca5c6094bcc0101f4c9d1ff48b6b34b&oe=57D13A2D

https://scontent-atl3-1.xx.fbcdn.net/v/t34.0-12/14182525_943326035794049_6434418_n.jpg?oh=ae9c47006b7f539be11cc63887d470bd&oe=57D13BB3

Also, the bucket for the exhaust wouldn't twist easily or come out. I had to really tug it out unlike the others which just slid out using a magnet. Could the bucket being stuck have an effect?