Water injection or water/meth systems work very well (see Snow Performance kits) to cure and prevent intake valve deposits.
You can also perform a *direct application of water into the intake that can do a great job to reduce and clean the intake valves and also combustion chambers exhaust and top of pistons.
The only true way to determine if any cleaning process is useful or effective is by scoping the intake before and after the service.
Harbor Freight Digital Inspection Camera Cen-Tech®- Item#62359
* this has been a long performed service to remove carbon deposits and other contaminants over decades on both direct port F/I engines as well carburetor engines. It does require a little understanding and experience to be successful.
You can also perform a *direct application of water into the intake that can do a great job to reduce and clean the intake valves and also combustion chambers exhaust and top of pistons.
The only true way to determine if any cleaning process is useful or effective is by scoping the intake before and after the service.
Harbor Freight Digital Inspection Camera Cen-Tech®- Item#62359
* this has been a long performed service to remove carbon deposits and other contaminants over decades on both direct port F/I engines as well carburetor engines. It does require a little understanding and experience to be successful.