brass carb balls and jetting

[rd400canuck]

I did a search but couldnt find everything i needed...

Ive drilled out the brass balls on my carbs for my 76 RD400c to be able to clean out the jests behind them.

To tap them I only go in a few threads correct?

What size is the tap and grub screw?

Also the stock jetting for this bike was 25 pilot and 115 mains.

I cant find where it was suggested but does 30 pilot and 120's sound like a good place to start?  It is bored 1mm over and 100% stock everyhting.

[m in sc]

correct, just a few threads to let it lock in and stop..
we had a nice write-up on the old forum. I -think- it was an M5 to cap it.

id jump to a 27.5 1st and leave the main alone for now. boring isnt going to make any jetting difference.

[Alain2]

M5 to cap with grub screw, or leave them open and plug the air lines of the bowls.

[m in sc]

i have always left them open as well.

-however-

chuck and i had a conversation at the gap 2? years ago about this, he likes to cap them.

personally, i cant see any direct benefit but he can chime in here, and hes way smarter than I am so. 

[SoCal250]

THE TECH LIBRARY »CARBURETOR - FUEL/AIR DELIVERY

[SUPERTUNE]

Yes, re-plug with a  5mm X .8 setscrew.
Tap only 2-3 threads NO MORE.
Make sure you hook up the bowl vent lines back to the lower plenum of the air box to work correctly with the stock #175 series bleed needle jets on stock log pipes. If running chambers leave them disconnected from the air box as the midrange stumble will be real bad.
Go up to a 135 main with chambers.
I use the UNI replacement filter, not oiled or very, very little.
30 pilots and 127.5 main jet is fine with the ignition timing @ 2.0mm BTDC.
Chuck