Hello, I plan to port my intake manifold but was wondering if I'll need to adjust my carb afterwards to compensate for the increased airflow. I already have HK 3" pipes on, Hypercharger, Speedstar module and a jet kit installed...dyno'd the bike and the air/fuel mixture is dialed in perfect at the moment. Does anyone know if I have to rejet based on their experience? If so, what in particular will I have to change? I hate to monkey with my carb now that I have it dialed in so sweet; my bike purrs like a lion! Thanks - RK

Porting makes you richer. You'll have to ride it and see if you need to adjust anything.

You really can't know until you do it. If it is truly breathing better after porting, it's going to require more fuel.

If the present carb settings are able to supply it, you'll be golden.

If after another dyno session, you learn that the fuel demand has become greater than the present carb setup can supply, you'll be back for a new jet, or more.

Porting, and most intake mods are for the purpose of more easily supplying more air containing oxygen... which requires that your carb somehow supply more fuel to mix with that increased air.

Agree with Musky here. If any change is needed it will be to reduce the fuel flow. Porting the R* manifoldincreases flow, but also reduces the manifold's internal pressure for any given flow rate. In the entire fuel chain this is the only mod that works that way for us, and we are an exception to what would normally be true for other vehicles. All other mods increase flow without reducing the internal pressure.

If we could maintain a consitent cross section within the manifold this situation would be reversed. We can't because we are changing the internal shape from a 't' to a broad 'y'. The middle chanber area will end up being non-optimal, but far better than the 't'.

End result is we end up with a higher ratio of fuel in the mix than we had before (air is less dense - like going to a higher altitude).

The amount you need to adjust is unique to each bike and manifold. With highly aggressive porting you may need to reduce your main by one size. A lot of self porting jobs can be compensated for with PMS adjustments and needle clip adjustments if needed.

Thanks for the input guys - I'm running just a hair on the rich side now (judging by soot color in exhaust), so maybe I'll be alright when I port... -RK.