Here are the before and after pictures of the Arctic Cat atv carb. that I just finished cleaning by soaking in Pine-sol. The before pics were taken with my phone so they are a little out of focus.
I soaked this one in about half Pine-sol and half water because the boiler I was using was a little too big. I heated it over low heat on the stove to speed up the cleaning. Afterwards I scraped the remaining calcium like deposits off with a small screw driver.
You have to be sure to really rinse the carb good with water after soaking.
There are a lot more write ups here. http://www.bing.com/...&sp=1&sk=&ghc=1
You can use it full strength and it does not seem to harm rubber unless you leave it too long. It caused the bowl gasket on this carb. to swell, but I soaked it several times over about 2 weeks trying to remove the white stuff.