[24_NateFrye]

I have a 400ex bored to 416 and have a stage 2 hotcam. I have a krome dg slip on exhaust without spark arrester. Stock intake and carb with foam filter. I was wondering if I should change my jets, and if so what to? If I should make more airflow through the intake box with holes? It runs good to me right now but I was wondering if this setup would be hard on my motor or anything. I’m asking to see what the best setup would be for me with what I have? Any help is greatly appreciated.

 

[Here 2 help]

Boring and cam change do not affect jetting - changes to the exhaust only affect top end jetting - for a low restriction exhaust a 2 to 4 bump in main jet size is all that's required - changes to the intake affect jetting through the entire RPM range - the jet changes needed will be as individual as the modifications made. Just have to make the changes and then rejet as required - there is no chart to go by, make a change and rejet as needed. It's a tuners job and what works for one does not always work on another. Just the number of holes, size of the holes and location of the holes will dictate the jetting requirement.

 

[24_NateFrye]

Boring and cam change do not affect jetting - changes to the exhaust only affect top end jetting - for a low restriction exhaust a 2 to 4 bump in main jet size is all that's required - changes to the intake affect jetting through the entire RPM range - the jet changes needed will be as individual as the modifications made. Just have to make the changes and then rejet as required - there is no chart to go by, make a change and rejet as needed. It's a tuners job and what works for one does not always work on another. Just the number of holes, size of the holes and location of the holes will dictate the jetting requirement.

Okay, thank you. How would I tell between what jets and holes are a good setup? Will it just run good or bad?

 

[Here 2 help]

Yep - if it runs bad consider what you did and compensate - if you reduce the restriction to air flow, you need to compensate by matching the reduced vacuum in the venturi of the with more fuel for the faster flow pf air to pick up

 

[24_NateFrye]

I mean, I think it runs good right now. Should I still change the jets to a 4 like you said? Or does it not matter?

 

[Here 2 help]

If it runs fine, then run it - only change the jets when required by the modifications you make

 

[24_NateFrye]

Okay, thank you