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Piston knock on 301rr?

Featured Replies

In theory; your piston wobbled because of either tightness in the wrist pin bearing or a jam sandwich in the piston rings.

I’d be checking the internal diameter of the con rod small end. Even with the slightest play it will give a knocking noise. The piston doesn’t do much other than support the rings, which do all the hard work and wear considerably. If the con rod is slightly out of specification everything will wear as it won’t be runnng true and it will do the same again

Edited by jrsunt

  • Author

Lemur what do you mean with jam sandwich? 

 

3 hours ago, bobb said:

Lemur what do you mean with jam sandwich? 

 

When a piston ring pack becomes gummed up from bad fuel the rings stick in the piston grooves, then everything starts to go badly. Once you experience it you will know why I call it a jam sandwich.  

On 12/20/2025 at 9:02 AM, lemur said:

You sure you want to hone a plated barrel 🤔 don't think you are suppose to do that.

I've had a few plated dirtbikes & have given them a light hone before installing a new piston & rings, i know a lot of other Blokes that have done the same, as long as the mechanic has the correct tool & knows what he is doing there should be no problems. 

14 hours ago, eagle8 said:

I've had a few plated dirtbikes & have given them a light hone before installing a new piston & rings, i know a lot of other Blokes that have done the same, as long as the mechanic has the correct tool & knows what he is doing there should be no problems. 

So you are scratching up your fresh new spray coat of ultra hard nickel and silicon carbide that is actually harder then your piston rings for what purpose 🤔 

It's to prepare the cylinder surface for the new piston & rings plus it helps with lubrication :)                                                                                              They are given a hone before their first use with a diamond stones hone, most good mechanics have 1 in their assortment of tools .

Edited by eagle8

  • 1 month later...
  • Author

new piston and rings in the mont and it runs a lot nicer now no more rattle and it feels more powerfull.

 

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