Main jet size change

In my Clymer book it shows that the main jet was 120R in the 81-82 model year and in 83 it went down a size to 117.5.

I was wondering why it downsized? All the other parts stayed the same.

I bought a kerker # 127-61001 I have stock Air box with K&N filter and I want to figure out what size main jet to use.

EPA

That is what I thought "EPA". So a bigger jet would help restore the some performance back before the "EPA"


Not sure what size jets to get Mikuni Large Round Main Jet
120 or 122.5 or 125 up from 117.5

KZ1100 Bully wrote:

That is what I thought "EPA". So a bigger jet would help restore the some performance back before the "EPA"

Unless they screwed with the needle's taper or something else too.

I think I will start with 122.5 mains and see how they work. I don't think I need to make to drastic size change but I really don't know. Only way to learn is to try.

Thanks for the help so far guys.

I would have 20 idle jets while you are getting them. Roy

roy-b-boy-b wrote:

I would have 20 idle jets while you are getting them. Roy

I don't see any such jet in the book (idle jets):
I have a pilot jet at 40
Jet needle 4cg14
Needle Jet Y-1
and a idle mixture screw

Sorry, I was thinking 26mm.

I have 40's in my 36's. Roy