Cylinder Pinging

[hE]

I've got an '03 PW50, about 6 months old, and about 50 hours riding time on
it. About 3-4 weeks ago, I noticed a "pinging" or rattling noise coming
from the cylinder. Thought maybe it was running too lean but it checked out
OK. Then I thought it was the fuel so I switched to a 93 octane...still
pinging. Compression checks at around 115-120 psi. I removed the head and
jug and decarburized the piston crown and head and checked for signs of
scoring....didn't find any. I'm out of ideas. Any suggestions greatly
appreciated.

[The Older Gentleman]

Post by hE
I've got an '03 PW50, about 6 months old, and about 50 hours riding time on
it. About 3-4 weeks ago, I noticed a "pinging" or rattling noise coming
from the cylinder. Thought maybe it was running too lean but it checked out
OK. Then I thought it was the fuel so I switched to a 93 octane...still
pinging. Compression checks at around 115-120 psi. I removed the head and
jug and decarburized the piston crown and head and checked for signs of
scoring....didn't find any. I'm out of ideas. Any suggestions greatly
appreciated.

I think what you've got is probably normal two-stroke
ring-dinga-dinga-ding cylinder resonance.

Many air cooled two-strokes had rubber bungs rammed between the fins to
counteract it.

[Kaybearjr]

Post by The Older Gentleman
I think what you've got is probably normal two-stroke
ring-dinga-dinga-ding cylinder resonance.

The "ring-ding" sound comes from lean misfire when the throttle is closed. The
2-stroke has a large volume of lean fuel/air mix in the intake tract and
crankcase and it misfires under low load, closed throttle operation. The fixed
ignition timing doesn't help the situation. The engine would stall if the
inertia of the motorcycle didn't keep it turning and running. 2-stroke
motorcycle engines keep running, but 2-stroke outboard motors will often stall
when the throttle is closed...

Post by The Older Gentleman
Many air cooled two-strokes had rubber bungs rammed between the fins to

counteract it.

That was called "cylinder ringing". The "ring-ding" noise
is also called 2-stroke "yack yack"...

[The Older Gentleman]

Post by Kaybearjr
2-stroke "yack yack"

....don't look back.

[Kaybearjr]

Post by The Older Gentleman

Post by Kaybearjr
2-stroke "yack yack"

....don't look back.

Yakety yak (don't talk back)

Take out the papers and the trash
Or you don't get no spendin' cash
If you don't scrub that kitchen floor
You ain't gonna rock and roll no more
Yakety yak (don't talk back)

Just finish cleanin' up your room
Let's see that dust fly with that broom
Get all that garbage out of sight
Or you don't go out Friday night
Yakety yak (don't talk back)

You just put on your coat and hat
And walk yourself to the laundromat
And when you finish doin' that
Bring in the dog and put out the cat
Yakety yak (don't talk back)

Don't you give me no dirty looks
Your father's hip; he knows what cooks
Just tell your hoodlum friend outside
You ain't got time to take a ride
Yakety yak (don't talk back)

Yakety yak, yakety yak
Yakety yak, yakety yak
Yakety yak, yakety yak
Yakety yak, yakety yak

Coasters 1950-something?

[David Hajicek]

Thank you. That brings back memories.

Dave Hajicek

Post by Kaybearjr

Post by The Older Gentleman

Post by Kaybearjr
2-stroke "yack yack"

....don't look back.

Yakety yak (don't talk back)
Take out the papers and the trash
Or you don't get no spendin' cash
If you don't scrub that kitchen floor
You ain't gonna rock and roll no more
Yakety yak (don't talk back)
Just finish cleanin' up your room
Let's see that dust fly with that broom
Get all that garbage out of sight
Or you don't go out Friday night
Yakety yak (don't talk back)
You just put on your coat and hat
And walk yourself to the laundromat
And when you finish doin' that
Bring in the dog and put out the cat
Yakety yak (don't talk back)
Don't you give me no dirty looks
Your father's hip; he knows what cooks
Just tell your hoodlum friend outside
You ain't got time to take a ride
Yakety yak (don't talk back)
Yakety yak, yakety yak
Yakety yak, yakety yak
Yakety yak, yakety yak
Yakety yak, yakety yak
Coasters 1950-something?

[Kaybearjr]

About 3-4 weeks ago, I noticed a "pinging" or rattling noise coming from the

cylinder.

Check out that exhaust pipe restrictor. Baffle could be plugged up. If the
exhaust can't get out, fresh mixture can't get in and a 2-stroke engine will
start pinging...

Engine gets so hot, the oil starts dieseling...

Really rich mixtures diesel in a 2-stroke...

Spark plug heat range might be too hot, causing preignition...

[hE]

Post by hE

About 3-4 weeks ago, I noticed a "pinging" or rattling noise coming from the

cylinder.
Check out that exhaust pipe restrictor. Baffle could be plugged up. If the
exhaust can't get out, fresh mixture can't get in and a 2-stroke engine will
start pinging...

No baffle, and the spark arrestor has been thoroughly cleaned.

Post by hE
Engine gets so hot, the oil starts dieseling...
Really rich mixtures diesel in a 2-stroke...

That's interesting. I've suspected the stroke on the oil injector pump
needed to be adjusted down for some time now. I haven't done it because I'm
afraid I'll get it too lean and seize. These &*^!@ oil injectors are a bear
to adjust properly and even worse to try and measure. I didn't know about
the dieseling though...sounds like I might need to bite the bullet and do
it...or disconnect the pump and go premix...thanks for the suggestion.

Post by hE
Spark plug heat range might be too hot, causing preignition...

Another good suggestion. I'll check that out too.

[Kaybearjr]

I didn't know about the dieseling though...sounds like I might need to bite

the bullet and do it...or disconnect the pump and go premix...thanks for the
suggestion.

Before going to premix, be sure that the oil injection pump isn't necessary to
feed the rod big end bearings, like is Suzuki's practice...

Also, some 2-stroke crankshaft designs had big thin washers locating the rod
side-to-side. Those designs need lots of oil in the mix...

Post by Kaybearjr
Spark plug heat range might be too hot, causing preignition...

Another good suggestion. I'll check that out too.

I had hot spark plugs burn holes in my pistons at least twice before I figured
out that I couldn't run the same spark plugs in my car and my Yamaha too...

And, I also discovered that carbon plugging up the baffles made my Yammie
ping...

Pinging sounds like a loose valve, but you know that your 2-smoke has no valves
to get loose...

Pinging eats away at the aluminum piston top a little bit at a time...

Detonating makes a metallic clanging sound or bang, and detonating will break
the porcelin insulator nose of your spark plug...