Jetting for Z400 with HMF Sport Series SLIP-ON

[FastZ]

I was wondering if anyone could help me by letting me know the recommended jetting specs for my Z400 at an elevation of 1800ft. I have the sport series slip-on muffler with stock head pipe, stock motor (no mods as of yet) and Mikuni 160 main jet. Is this a good jet for this altitude? The HMF website recommends a 170 jet, but when I installed the 170, my motor stumbled a lot, it just spit and sputtered. The 160 main seems to work well but I was just wondering if someone else had some ideas. Plus, if I were to buy the HMF head pipe, would I have to buy a new muffler or could I use the slip-on one? Thanks.

FastZ

[Mike/HMF]

Always consider all elevations temperature and conditions effect jetting. We tested our z-400 and ours worked with the 170, yours might be different. It is always a good idea to do a spark plug check after you re-jet. Check it out here in the forum step by step on how to do a plug check. Also the z-400 slip-on will work with the head pipe you just need to cut alittle bit and we do supply the template. Any questions give us a call. 866-HMF-PIPE.
Mike/HMF.