1984 gs 1150 jetting question

[joe bio]

The stock main jets in my GS 1150 are 120 for cylinders 1&4 and 122.5 for 2&3.
I have installed Vance & Hines 4 into 1 header still has the stock air box.
Should I be putting in different size jets like the stock when I increase the jet size to compensate for the header?
Example 135 for 1 & 4 137.5 for 2&3

[Carter Turk]

My wife's 1150 has 135 mains, with 4 K&N's and jet kit. Your example jet sizes might have you running a bit rich. Not sure on stock air box w/pipe, maybe 125's on all 4.

[posplayr]

My wife's 1150 has 135 mains, with 4 K&N's and jet kit. Your example jet sizes might have you running a bit rich. Not sure on stock air box w/pipe, maybe 125's on all 4.

The stepping in the jets is to richen the mixture on the inner cylinders as they tend to run hotter. I have never seen a difference on my 1166, but it stands to reason that any problem at 1135 is worse at 1166. I know Chef1366 has his 1230 stepped so it would probably not hurt anything to continue that approach.

In line with Carter's reco, I would probably go 125/127.5 and see how the plugs look. I don't remember the guideline but it seems like you would need more than 122.5/125 (i.e. one step up). It would also depended on your altitude.

The pods make a much larger difference.