I have been working with a fellow that has been around motorcycles longer than I. That's a long time.

He's been playing with carbs for most of that time. He is the fellow modifying the Mikuni that I bought.

He discussed opening up the airbox with at least 6 1 inch "button" air filters on the sides of the airbox. Obviously the bike needs more air to make power.

That kind of falls in place with all the data we have heard about "double snorkles", airbox lid off and other modifications.

I guess the next step is more air to the carb!

 

why not just run with the lid off?

 

I'm just about there - I had previously done the double snorkle mod, and I have both snorkles removed right now so there's really not much more plastic left on the lid itself. I may as well pull it.

 

Me no liddy...

 

Would you recommend a 128 main jet over a 125 main jet if you go the no lid route since there will be more air in the carb?

 

I am running a 145 mj. No lid.

 

WOW.. And your not running incredibly rich?? what type of riding are you doing? Mostly highway?

 

I found a BIG difference in noise level with no lid versus lid with no snorkels... It was just too clappy (muzzy quiet core out).
So I now have a modified lid installed (with some big holes in it).

 

I ride to the forest (30 miles) and ride another 50 in the forest and back home. Maybe just a little but top end pulls really good and plug looks ok. Maybe later on I will try a 140 or 138 for comparison.

 

DirtSurfer,

Keihin jets - which is the one most of us use - are different in size than other manufacturers jet. Dynojet uses a larger number than the Keihin jets do.