vintage engine rattling noise

[usafstud]

Hi,

I'm wondering what you guys think about the (penny) tingng noise of my 1972 Yamaha LS2 is making.

I don't know if this is normal or not. I going to start commuting with it again and my wife is planning on doing the Lake Eeri loop event with me on the bike.

1972 Yamaha LS2

2stroke

100cc

The only mod i have done is taking out the baffle packing to it.

http://s96.photobucket.com/albums/l200/usaf060stud/?action=view&current=4fccdf4f.mp4

Thanks,

Frank

[Jcarlson]

Bad valve? Just guessing. Nice ride BTW!! That's sharp for its age.

[Strictly Street]

Hard to tell from the video.

http://www.cmsnl.com/yamaha-ls2-1972_model8408/partslist/

[dorifto240]

Apart from being an actual penny?

Maybe it's just something around the engine that has come loose and is rattling.

Or it's CLEARLY NOT the valves.

Or maybe the ignition wires are arcing somewhere?

Edited March 27, 2011 by dorifto240
to save face and avoid punching myself in the nuts.

[DAC]

Everyone that suggested it's the valves.. please punch yourself in the testicles' date=' right now.

That engine sounds fine to me. You're most likely hearing internal engine noise being amplified off the cooling fins on the engine. Don't sweat it.[/quote']

:lol:

[ReconRat]

If it goes away or gets less when it warms up, I'd say it's the piston, rings, and cylinder wall. Those can make a ringing or bell like sound, particularly when cold. There's a lot of expansion on 2-strokes. It's all the heat generated from double the power stokes. They can be pretty loose when cold. Worst case would be stuck rings or worn piston skirt, but I'd think it would start smoking out the tailpipe with that.

edit: And yeah, it doesn't sound bad from the video. Just louder than normal maybe.

[chevysoldier]

There's a midget with a hammer inside.

[oldschoolsdime92]

Bad valve? Just guessing. Nice ride BTW!! That's sharp for its age.

You gave me a good laugh though!

[usafstud]

If it goes away or gets less when it warms up, I'd say it's the piston, rings, and cylinder wall. Those can make a ringing or bell like sound, particularly when cold. There's a lot of expansion on 2-strokes. It's all the heat generated from double the power stokes. They can be pretty loose when cold. Worst case would be stuck rings or worn piston skirt, but I'd think it would start smoking out the tailpipe with that.

edit: And yeah, it doesn't sound bad from the video. Just louder than normal maybe.

i do get a bit of white smoke

[Strictly Street]

i do get a bit of white smoke

2-strokes do smoke normally.

White-blue smoke is very normal.

No smoke and you might want to think about adding a bit more oil mix.

[Bubba]

Tough to diagnose if something/anything is wrong from the vid. Sounds pretty normal for a ring-ding. It would be helpful to check out a few things: Is the sound only when cold/hot? Does the sound change with engine temp/RPM/load? If the noise is most noticable when cold with no load and goes away (mostly) when warm/under load, I'd guess maybe worn wrist pin(s), or possibly some excess carbon buildup in the combustion chamber. From the pics, it looks like it'd be worthwhile to do the repairs, as it's a clean vintage smoker--not many of them left!

[usafstud]

been riding it around the block lately and it seems to be fine.

another problem I been having is that sometimes the power just wants to cut out. I need to give it gas to keep it alive for a minute or two and be back to normal.