Rear choke pull off

[Haagdakta]

In Cliff's book he states that the rear choke pull off can be somewhat difficult to modify. Just curious to know what makes the rear pull off more difficult to modify? Can the restriction (if it has one) be modified like the front pull off?

[Cliff Ruggles]

Many will have a "vent" hole in them so drilling on the restriction or feed hole may not give the intended results. 

They also have a large canister, and unless you are timing the release with a vacuum pump or using the engine as a test stand they may not work the same way as simply releasing them and watching how quick they open......Cliff

[Haagdakta]

Thank you for the reply!