Main jet/ pilot jets ?

[0T02G]

I NEED TO UPDGRADE TO 150 AND 50 JETS. i KNOW THAT THERE THE ROUND ONE BUT ARE THEY THE LARGER OR SMALLER ONES. I WAS JUST GOING TO BUY ONLINE AND I DON'T HAVE MY CARBS WITH ME TO TELL.
I WAS JUST GOING TO ORDER FROM DENISE KIRKS.

1981 XS400

THANKS

 

[JARichmond]

Main jets are the 150s you want, where the pilots are 50s. They are the larger ones in the center of your carb bowl. The pilot jets are smaller, and can be found on the side of your needle shaft (where your main jet is) in the same orientation. Make sure you don't strip your original pilots in the shaft or you'll be up sh*t creek without a paddle.
What's your setup if I may ask?

 

[0T02G]

Making it into a bobber. I removed the air boxs and added single k@n type air fillter, cut my exhaust down androtated it barely goes under the front of the engine has 4" baffles installed.
know where they, they make square, large roundand smaller rnd for carbs, I now they dont use the square one, I was wondering which of the two rnd ones does it use.

Thanks

 

[shamus]

know where they, they make square, large roundand smaller rnd for carbs, I now they dont use the square one, I was wondering which of the two rnd ones does it use.

Thanks

Say what?

 

[JARichmond]

The main jets are wide and short in order to thread on to the shaft similar to a bolt. The pilot, on the other hand, has a small diameter, long thread, and fits INSIDE the pilot shaft. I don't have my carbs apart (and don't want to do so as I struggle on a regular basis to get the throttle cable hooked up) so I don't have pictures available but you can likely do a search on Google for "Mikuni BS34 main jet and pilot jet" and have a look at the images that come up.
Hope that helps. If not, just let us know and someone else will likely be able to chime in with a more satisfactory answer

 

[Pork Chop]

I am 99% sure the xs400 uses the small round main jet. But i would wait for a forum guru to confirm this.

 

[drewpy]

LD is pilot and HD is mains