A moderate rolling boil for about 30min. remove all plastic or neoprene parts first. I would spray them out with cleaner and try to get all passages open. I also use compressed air to blow through passages. Some floats are plastic on newer carburetors. This dissolves a lot of varnish.
You will need a carburetor kit normally when you do this.
The only correct way to be sure they are correct, is to dismantle each one and thoroughly examine each piece, clean , and reassemble with new gaskets, and soft parts.
But if you are looking for an easier way out, you could try this. One at a time spray each one with spray Gum-out carburetor cleaner, or equal. The air bleeds need to be sprayed. These are the small holes that are accessible from the main air inlet. There are also some small holes that should be visible from the bottom of the carb where it bolts to the engine. These may be above and/or below the throttle butterfly.
You will also need to spray cleaner into the fuel inlet, slosh it around, then turn the carb upside down and dump it out. You should probably repeat this step a few times as the fuel inside the carb is what gummed up most.
If you are comfortable dismantling the carbs already, forget what I said. I was talking to someone else. good luck.
Very interesting information here. I have been a carburetor re builder for over 20 years and have found the best method of professional crab cleaning is to use a ultrasonic cleaner. The problem is a good ultrasonic cleaner cost $500-$600, but I found a company who sells them for $279 and even offed free shipping, just wanted to let everyone know out there because I am so happy with this purchase and hope to save you some money as well.
Carburetor Cleaning Method?
Re: Carburetor Cleaning Method?
Good Answers: