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Discussion Starter · #1 ·
After my engine is at normal operating temp at around 3K rpm with slight acceleration the engine makes a sound that resmbles piston slap. It's a relatively annoying kocking that goes away with more or less throttle. I can reproduce it sitting still but notice it most in 3rd gear while moving. Maybe it's just echoing in my helmet at that point. Any comments?
 

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I think someone said that its the cam chains.....Do a search...Been awhile since I read it...Think it said they are self adjusting and it goes away after awhile...
 

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for us folks that are still learning about engines, what is piston slap?
 

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Whatever it is, this person doesn't like his Chevy doing it :eek: :swear:

 

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Discussion Starter · #5 ·
phaed said:
for us folks that are still learning about engines, what is piston slap?
This is when a member of a certain basketball team from Detroit asks for a sexual favor you aren't about to provide, no way no how!! You slap him!! That's Piston Slap!

No, seriously, here you go...It is the secondary (sideways or perpendicular) movement of a piston against the side of a cylinder bore where the primary movement of a piston is intended to be parallel (up and down) to the cylinder bore. The piston skirt "slaps" the cylinder wall.

Piston slap is caused by improper fit of the piston in the cylinder bore. Typically the piston is too small or the bore is too large, making the piston wobble back and forth in the cylinder. When the engine is running this slap can become very loud and annoying. It makes a regular car engine sound very much like a diesel engine.
The noise that piston slap produces usually clears up as the engine heats up. The pistons expand and fit in the bores more snugly.

Hope that helps
 

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Discussion Starter · #6 ·
J R said:
The pistons skirts are kinda short and can make a little noise.Im not sure of your mods but id make dang sure the noise your hearing aint spark knock.Im sure its prolly just a little piston slap tho these bikes make a little noise.Its not a problem.
JR,

The noise I'm hearing comes and goes with slight acceleration. Sounds metallic to me, but maybe it is a spark knock. No mods...everythingstock.
 

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"relatively annoying kocking that goes away with more or less throttle. I can reproduce it sitting still but notice it most in 3rd gear while moving."
Pobably not related but...my c50 had the exact same symptoms.
It had a slight ping from new. Took to dealer and they claimed it's "normal" for that type of engine. Got progressively worse over time, same symptoms you described to a t. Took it in and long story short after 2 weeks of testing everything and going back and forth with Suzuki, it was determined my fuel pump was not pumping enough gas. Replaced it (no charge) and the thing ran better than when new and ping / knock was non existant. Of course, I just sold that to buy my new 109r. Should be in Friday... :bigthumbsup:
 

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the clutch will produce some knocking sounds too. If the noises this bike makes gives you the heebee jeebees then never under any circumstances ride or own a Ducati with a dry clutch, Any air cooled HD, or any bike with Flatside carburetors. you will go insane...... ::)
 
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