Catastrophic engine failure (lubrication helps engines)

[chef1366]

If you were running lean the pistons probably overheated, expanded, and scraped on the cylinders. That may be where the flakes came from. When you pull the cylinders you'll know for sure. The piston skirt will show any damage.

If that's the case, mike the pistons and if they are still in spec you may be ok to use them again. Run a hone through the cylinders, possible install new rings and (best case) you'll be on the road again.

Good point!

[spchips]

Death tick and sucking power is often the Journal bearings.

(which the 650's do have) They are good bikes but not bulletproof roller bearing motors.

[MrZig]

Okay here's a small update. It might be related with the cam timing.

Clymer says that on the GS450's, I need 18 links between the cam marks. Even though mine is a GSX400, everything that the manual has said for the GS450 has applied for my engine.

As you can see, I have 20 links between the marks:




Now, with the timing marks setup like this (I'm not sure if it's correct?)



The exhaust cam is pointed here:




I think something is haywire here and I may have bent a valve.

I noticed that when spinning the engine with a ratchet, the chain in between the camshafts is pretty taught at times, then if I spin it some more it loosens up a bit, then if I spin it more it tightens up, rinse and repeat.

[mikluha]

Well, this one is easy. When the intake cam chaft opens the valves, it needs to be pulled by one side of the chain (top section). When it closes the valves, it need to be held back by the other portion of the chain ( that goes from bottom to top) and the top section loosens.

When you rotate you engine do you fill ups and downs? Why do you expect the tension to be the same?

I noticed that when spinning the engine with a ratchet, the chain in between the camshafts is pretty taught at times, then if I spin it some more it loosens up a bit, then if I spin it more it tightens up, rinse and repeat.

[mike_of_bbg]

Sounds like a problem with the cam chain tensioner. Messed with it recently? Did you try a compression test? If you had bent a valve surely you would have low compression.

[mike_of_bbg]

yeah, but does it visibly "droop"? There might be a bit of loosening, but the cam chain tensioner should take most of that out.

[waterman]

Okay here's a small update. It might be related with the cam timing.

Clymer says that on the GS450's, I need 18 links between the cam marks. Even though mine is a GSX400, everything that the manual has said for the GS450 has applied for my engine.

As you can see, I have 20 links between the marks:




Now, with the timing marks setup like this (I'm not sure if it's correct?)



The exhaust cam is pointed here:




I think something is haywire here and I may have bent a valve.

I noticed that when spinning the engine with a ratchet, the chain in between the camshafts is pretty taught at times, then if I spin it some more it loosens up a bit, then if I spin it more it tightens up, rinse and repeat.

Is it possible that the cam chain skipped a couple notches which resulted in the 20 links of space instead of 18? If the cam tensioner is wonky this could occur. Hopefully the valves haven't been bent from contact with pistons if timing was off. I found that the previous owner had the exhaust cam off by one tooth and the intake one tooth long also, bike ran okay. Are you going to pull head and check valves? I would suggest retiming intake cam correctly and then mechanically turn over motor while paying attention to valves to see if they are closing.

Just want to clarify that I do not know the correct cam timing for your model so please double check, I am only making suggestion from what you have disclosed to us. Hopefully it is only a bad tensioner.

[donimo]

The gsx400 is the same down below, but the head is totally different, I will check my book and see if it mentions anything.

[donimo]

My book says 20 is correct.

[MrZig]

20 is correct? Okay, howabout this:

Clymer says that with the T aligned correctly (meaning Cylinder #1 is at TDC, right?) the #1 arrow on the exhaust sprocket should be pointing foward at the gasket level.

On my engine, when the T is aligned and #1 is at TDC, it's arrow #2 that is pointing forward at the gasket level.

[donimo]

And I quote"

"With the "T" mark in exact alignment with index mark on the static plate of the ATU (#1 at TDC), the Exhaust camshaft should have the #1 marked arrow pointing flush with the upper mating surface of the head."

just like in the picture you sent me earlier:

http://img198.imageshack.us/img198/859/camshafttiming.jpg

sounds like you skipped a few teeth, hopefully nothing is wrecked and you can reset and go, not sure though from what you described...

[MrZig]

And I quote"

"With the "T" mark in exact alignment with index mark on the static plate of the ATU (#1 at TDC), the Exhaust camshaft should have the #1 marked arrow pointing flush with the upper mating surface of the head."

just like in the picture you sent me earlier:

http://img198.imageshack.us/img198/859/camshafttiming.jpg

sounds like you skipped a few teeth, hopefully nothing is wrecked and you can reset and go, not sure though from what you described...

Okay, here's the weird thing. Your manual says the TDC method is the exact same thing I've been doing. IF this is true, then both of my cams have jumped four ****ing teeth. How does this happen?

Step one: Make sure the #1 piston is at TDC and the "T" aligns with the mark.

Timing Mark:

http://img31.imageshack.us/img31/4304/dsc0016.jpg

Piston #1 at TDC:

http://img29.imageshack.us/img29/7478/dsc0018.jpg

Step two: Make sure the arrow #1 on the exhaust camshaft sprocket is
pointing forwards to the gasket surface

Arrow #2 which should be #1

http://img30.imageshack.us/img30/9910/dsc0017c.jpg

How the flargin blargin does this happen? How does it even run? Something can't be right here.

[reddirtrider]

I seriously doubt your cams jumped 4 teeth, let alone 1. If they are off, it probably means they were off since the last time the cams were out.

[MrZig]

I seriously doubt your cams jumped 4 teeth, let alone 1. If they are off, it probably means they were off since the last time the cams were out.

Exactly what I was thinking, them jumping 4 teeth just isn't possible. The questions now are A) Why is it running at all and B) Why only now is it causing problems for me?

This is mind boggling.

[donimo]

does having the Other" T mark (180* over) make it right? My book has the "Tl lF" one as being TDC, you might me on the exhaust stroke there?