Whether you need cleaning or not is questionable, but we all know you are going to do it anyway. ![smile](https://www.rotax-owner.com/media/editors/tinymce/plugins/emoticons/img/smiley-smile.gif)
The Rotax Powers-That-Be are never going to bless any of this.
The simple way would be to run a bottle of the many "Engine FLUSH" products through it just before an oil change.
Back in the day (>40 Years ago) we would pour a pint of kerosene into the oil and let it idle for 10 minutes before changing the Oil.
The "Flush" products are just a fancy bottle with the same procedure.
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If you really want to know if it did any good...
1. Do an actual Complete Oil change on a warm engine.
2. Run the engine up to operating temperature.
3. Drain out a pint of the new Oil and save it in a clean clear container.
4. Add a pint of the "Flush" product of your choice.
5. Run the engine again for 15 minutes at 2000-3000rpm. (High Idle Only - Do NOT Fly it!!!)
6. Drain out another pint of Oil and save it in a second clean clear container.
7. Compare the Before and After Oil. Share a photo of the results with us; especially if there is a big difference.
8. IMPORTANT!!! Do another COMPLETE Oil Change. Do not leave the "Flush" in the engine.
If you would be willing to sacrifice an Oil Change for the sake of knowledge, we all promise to be extremely grateful. ![cool](https://www.rotax-owner.com/media/editors/tinymce/plugins/emoticons/img/smiley-cool.gif)