Abandoned: jets for my 81 XS400SH

[oldgeek]

Hi all,
I have been dismantling/cleaning the carbs to see if I can get this beast running.
I have a few questions about what i found. I can tell someone worked on the carbs, but i do not know if they changed jetting.

#1) The pilot screw plugs were still installed. I removed them, and the pilot screws were about 3 1/4 turns out. Also there was only a spring, no washer, and no O ring. Do I need to install the washer and O ring?

#2) The main jet is 135, the book says it was 142.5. Should i keep the 135 for now?

#3) The pilot jet is 42.5, and agrees with what the book says...should i keep the 42.5 for now?

#4) The air jet is 155 The book says 45. What should i do here? I cannot seem to find any info in the forum that mentions air jet sizes.

#5) The jet needle (5gz9) is not adjustable on this particular carb. Has anyone here used the jet needle kit from MikesXS designed for a XS600 on a XS400? will it work?

One of the reasons i ask these questions is because the bike came with no air boxes or filters installed. i will RUN CHECK it without filters first, just to see if it runs ok. I plan on getting POD filters, and straight pipes eventually if it passes the RUN CHECK.

 

[bcware]

The sizes in the manual are mostly wrong. Ignore the air jet thing; I seriously doubt they have been changed and Haynes has a typo in their book where they mislabel a photo and call it something else. Additionally, these particular jets are very hard to find (I was never able to find any).

I heard that the o-rings tend to disintegrate over time.

Someone else can tell you what jets are supposed to be in the '81, but it wouldn't hurt to post a photo of the carbs to make sure they are actually from an '81.

 

[lhaolpa]

My pilot screws[on top rear of the carbs]also had 1 washer,no 0-rings.It is an '82 seca,but basically the same with some changes. Mine has 127

and 117

main jets,otherwise is about the same.I will have to move to larger sizes maybe,but will try to shim the needle with washers,which I have.On my Dt400 dirt bike,I raised the needle,and went up one size on the mains,as 2-strokes are sensitive to mixture and need to be a little rich.4-strokes don't need to run rich though,or too lean,as detonation can be bad. lha​

 

[OliverB]

Mikuni or Keihin carbs? The Keihin carb air mix screws have o-rings and a washer, Mikuni do not. If Keihin, order a set of air mix screws with o-rings and washers from mikesxs.com

 

[oldgeek]

Thanks all for the input so far. Here is a picture of what i am working on:

I am waiting on a few items to get here, so i can put them back together.