Not really a GS, but I have a friend in need - knocking engine

[liloaty]

Hey guys, sorry I know this isn't a GS - not even the same family for that matter, but I have a friend who is getting desperate and a bunch of you guys seem to know what the hell youre talking about. Can you take a listen to this video and maybe give me some insight as to what is causing this knocking? Oddly enough it doesn't knock if the plugs are out.

Its a 1996 EX250 Ninja

http://www.youtube.com/watch?v=LzbisWQ9obk

The sound in the video doesn't do it justice, sounds like metal slamming into metal. Any and all advice is appreciated.

[Dave8338]

Not good...

Blown head gasket? Holed a piston? Broken ring(s)? Wrist pin? Could be any of those and maybe a few more. Hard to tell from the audio. If it only does it when the plugs are in, it would suggest that it is compression related and therefor lesson or go away, once the plugs are removed.

[derwood]

your friend didn't perhaps run it out of oil? thats what my wifes 440 sounded like when that happened.....ended up being a connecting rod.

[earlfor]

Its hard to tell from the vid. The sound isnt separated from the starter noise. Perhaps a microphone held next to the cylinder barrels on the opposite side from the starter would clairify it somewhat. It appears too deep a tone to be cam related, best guess at this point is a connecting rod bearing.
Can you get a more distinct sound vid?

Earl

[catbed]

thats exactly what mine sounded like when i bent a valve.

[TheCafeKid]

Sounds a bit like piston slap to me. One of my GS motors makes an odd sound, similar to that, but not quite as pronounced, tracked it down to the cam chain tensioner tho...Try using a screwdriver as a stethescope. Hold the handle to your ear, and then place the blade on various parts of the motor, will help to isolate the sounds area.

[liloaty]

Hey guys try this video out...much much better sound.

http://www.youtube.com/v/Y8yL-P88Tls

[earlfor]

Thats a lot more clear. I'll put my vote on a piston hitting a valve. Best guess is a bent valve and cam chain jumped a tooth. Did the guy miss a shift and seriously over rev it by chance? I would go ahead and pull the head.

Earl

Hey guys try this video out...much much better sound.

http://www.youtube.com/v/Y8yL-P88Tls

[liloaty]

Thats a lot more clear. I'll put my vote on a piston hitting a valve. Best guess is a bent valve and cam chain jumped a tooth. Did the guy miss a shift and seriously over rev it by chance? I would go ahead and pull the head.

Earl

Well that was my first guess. I suppose that makes me feel a little smarter and the girl who owns the bike a little more depressed. I don't actually know what she did, all I know is she called me to help her get her bike started and it was knocking like crazy.