Help choosing jet size?

[MacLeody]

Hey all,

So I cleaned my carburetors and got airboxes. When I bought this bike it had pods on it and it always backfired. When I took the carbs apart to clean them I striped out the main jet on disassembly, so I can't use it. I bought two new jet sizes to replace what was in there. I got 130 and 145 main jets. They originally had 135 jets (I didn't know the size when I ordered). I WILL be getting it rejetted, so this isn't permanent. I just want it to work somewhat when I take it to them mechanic. So my question is, I'm coming from a dirty carb with 135 main jets and air pods, it backfired with the setup so I'm assuming a lean mixture. I'm going to a clean carb with 130 or 145 jets and air boxes.

Should I try the 130 or 145 first? Does it matter? Keep in mind I will be getting it rejetted, I just want it to run when I take it in.

The motorcycle is a 1977 Yamaha XS360, the carbs are Mikuni BS38 and I'm in Utah so my elevation is about 4700 ft.

Thanks for any help!

 

[crazypj]

I would use the smaller size plus re-check the pilot system

 

[johngofast]

Welcome, I've tuned a XS360 here in the Salt Lake Valley and if I recall I ended up with 130 mains, center on the jet needle clip, and 3 turns out on the pilot. It was a completely stock bike and ran great.