Pilot jets stock Z1 w4into 1

I'm going through carbs for my 73 Z1 Motor.It is all stock/airbox and will use my 4-1 yosh or a new chrome kerker.I plan on one size up mains to 115's. the carbs already have 25 pilots,should I use them or replace with stock 20's
gregz

GregZ wrote:

I'm going through carbs for my 73 Z1 Motor.It is all stock/airbox and will use my 4-1 yosh or a new chrome kerker.I plan on one size up mains to 115's. the carbs already have 25 pilots,should I use them or replace with stock 20's
gregz

Here's some info from Z1E:

28mm (VM28SC) Z1 & early Z1-A
Main Jet 112.5
Air Jet 1.0
Needle Jet P-8
Jet Needle 5J9-3 - last number is the clip position where 1 is at the top of the needle (leanest) and 5 is at the bottom (richest)
Throttle valve (slide) 2.5mm cutaway
Pilot Jet 20.0
Air Screw setting 1 1/2 turns out

28mm (VM28SC) Late Z1-A & all Z1-B
Main Jet 112.5
Air Jet 1.0
Needle Jet O-8
Jet Needle 5J9-2 (last number is the clip position)
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5
Air Screw setting 1 1/4 turns out

Good Luck!

Edit --
Oops, confirming the already known oem pilot size doesn't help answer the question. :blush:
Wondering why the oem 20 pilots were replaced with larger 25's in the first place?

Here's an excerpt from Sudco Mikuni Tuning Manual 4th edition, regarding pilot jet size.

Good Luck!

The 20 pilots on the 73s were the largest pilots ever used on the Z1 & KZ1000 series of bikes. I ran mine in 73 with stock pilots and the 115 mains with the airbox on but the filter out at the drags. Went 12.19 @ 108.95 going thru in 4th that way. Not much now but damn fast back then for a stocker with a pipe. This was at sea level in Miami Fl.