The washers are bought at Radio shack. Use the search to find the part #.

The #4s still vary thickness in the sac. Get a micrometer so you can find 4 of them that are .02. Im stock and just put 2x.02 under each needle. More throttle response and the popping is gone. I think it just made it a bit richer.

I found variance from .02-.025 so you do want to verify the thickness. A $10 dial caliper will do that for you.

Good luck!

 

I agree, I also some some varience in the #4 washers and all were between .020 and .025. You can go to .070 without any problem if needed.