Bonneville America Forums Forums Technical Forums Performance Mods Main Jet Question

I just removed my stock airbox, put kn filters on, mounted "brokenfixed"'s battery bracket, etc. I tore the carbs apart using dinqua website as a guide. It appears that I still have stock needles, and 42 pilots. My main jets were 127.5 before the airbox removal( already had AI removed, snorkel gone, and drag pipes). Seeing some posts on here, I ordered 160 and 155 main jets from Brent. I put the 160s in and the engine was not happy at all. It idleed ok, but when I twisted the throttle, there is major hesitation. It looks as though there was some moisture coming through the pipes as well. I then changed the mains to 155. The idle is fine, less moisture, but definite hesitation when you put it in first and go to take off. Also, I noticed during idle that when I open the throttle bodies a bit, the revs stay high for a couple of seconds before coming back down to idle.

Would it be safe to assume that I am still running rich and need to get smaller jets? Any suggestions on how far I should try to jump down next from those who have gone through this process? I would appreciate any assistance.

If you still have stock exhaust the jets are too big and have you adjusted the pilots screws after the mods? You have to do that too or you will experience low end issues too.

I have straight through drag pipes. Which screws are you talking about? The d shaped ones or the pilot screws next to the main jets?

what screw next to the jets? I mean the screw in front of the bowl on the under side of the carb that adjusts the A/F mixture, the one that you need a D tool on for some bikes.

The D screw is for the air fuel mixture. That should really just be for fine tuning right and getting rid of the pop on deceleration?

The pilot screws are for making A/F adjustments but not necessarily for getting rid of decel popping. If you have less restrictive pipes some decel popping is normal. Turning the screws to eliminate it will probably end up set too rich a mixture.

Get the bike to a dyno if possible which will tell you quite a bit about your set up and what needs to be corrected.