Cleaning Fuel Passages, Testing Seals

I have broken my carburetor rack apart to replace the fuel line o-rings and to test the throttle shaft seals. I have 2 questions: What type of cleaner is best used to clean the gunk out of the fuel passages? How can I test the throttle shaft seals with the carburetor off the bike?

 

Any good spray carb cleaner and a small round brush will clean them. Sometimes there is hard gunk in them and a piece of wire will get it clean.
You can't test the throttle shaft seals with the carbs off the bike. You have it down that far might as well replace them.

 

Rick had posted a while back about putting some Marvels Mystery Oil on the shaft seals. If it drained quickly through the shaft seal, then the seal may be suspect.

 

"Field strip" them; everything EXCEPT the butterflies and throttle shafts.

Clean. Replace o-rings on pilot screws and on outside of valve seats.

Here's an exploded Mikuni: http://xjbikes.com/Forums/viewtopic/t=31061.html

What you can do, is to look at the seals on each carb that you CAN get at. Without breaking the rack, you can only get to the outside seals on #1 and #4. YOU can get to one seal on each carb. Inspect those. CAREFULLY. If they're split, cracked, or have become a pile of little disconnected rubber rings, then you can assume that their trapped partners are in similar condition. Likewise, if they're happy little campers, then their hidden twins are probably OK too. DO NOT subject them to anything that might harm them. CAREFULLY, using blunted toothpicks, nudge them from their seats and inspect. Gently clean, and see how pliable they are. Mikuni bits can either be in unbelievably good condition for their age; or toast. Haven't seen much middle ground.

I wouldn't pour anything on them that they wouldn't normally come in contact with. Not at their age.

 

Thanks for the input fellas. I removed the accessible throttle shaft seals on each carb and they were intact and still quite pliable. I am going to assume the others are in likewise condition.