717 carbs

[bradleysomers73]

Hi guys. I have a 1996 GTI and am changing the corroded dual carbs to a single BN40. The carb is brand new and comes with needle and jetting for a 98 model. I notice the later models use a different pilot jet and needle. Anybody know the reason why?
If it’s only about economy and emissions I’ll stick with what I’ve got.

 

[BrianMoore]

My single carb 97 GTI had an off idle bog. I put on the new later model replacement carb with different jets etc. Without opening it up or touching the screws, the bog is gone and it runs flawlessly.

 

[lagojaguarasp]

Could be because all 98 and later model carbs have an accelerator pump on them. Iread somewhere that the previous ones relied on a fatter low speed to tune out the off idle bog.

 

[mikidymac]

Yes, it is because of the accelerator pump.
Go with the newer jetting with the new accelerator carb.

 

[bradleysomers73]

Yes, it is because of the accelerator pump.
Go with the newer jetting with the new accelerator carb.

The 98 carb comes with the accelerator pump but the different needle and pilot jet to the 99-00?

 

[bradleysomers73]

I’m thinking the needle is bigger to prevent lean condition at constant high revs?

 

[mikidymac]

I’m thinking the needle is bigger to prevent lean condition at constant high revs?

Not really since they changed the spring also.

I would just go with the 98 jetting.