I picked up a bike a few months ago with a super G Carb. It's an S&S EVO with edelbrock performer rpm heads hot cams 96 cubic inch. Higher compression but not are what. It runs decent but I know its rich. It has a thunderjet installed. My questions are...... What exactly is a thunderjet? Is it adjustable? Will S&S have details on my engine built 15 years ago, as the PO didn't know specifics? Where is the best place to get info on tuning my Carb to perfection?
I have never tuned before but am not afraid to try my best. Spent plenty of time in the garage too but any pointers are always much appreciated.

 

The Thunderjet adds another fuel circuit to the carb. Depending on the air bleed jet size in the T-jet it will determine at what RPM the T-jet starts squirting fuel through engine vacuum. More often than not they don't come on until around 4000 rpm or so.

Download a tuning guide from S&S's site. They are very simple to work on. Check with Zippers for T-Jet tuning info and air bleed jets.

Super carbs have a slow or idle jet and a main jet. The newer ones have a main jet air bleed inside the fuel bowl that determines when the main jet kicks which is helpful when tuning as opposed to the old ones that had a fixed main jet air bleed that is not adjustable.

the cool thing about a t-jet is that you can get the low speed (Slow jet) tuned to idle and run clean on the bottom, then tune the main jet to run clean in the mid range, then tune the T-jet for top end performance. The problem with Supers without the t-jet is that there aren't enough fuel circuits leaving you compromising the jetting, generally leaving it too rich in the middle to make up for decent top end jetting.

 

Is there any good way to know what jets I will want to try out without knowing the specifics of the engine or should I just open it up and see what's in it and adjust from there?

 

Trial and error has always been my best way.

 

I am in the same position as the OP. The one other question I have is do the jets have any size info on them anywhere? And in my case it seems as though the valve on the tjet is all the way closed.