• My 350x has a 10 25 1 wiseco compression ratio a high performance cam a...

    My 350x has a 10.25/1 wiseco compression ratio, a high performance cam, a supertrapp exhaust, and a mikuni 36 mm carburetor. I've been having troubles with blowing through spark plugs. When I bought the machine it had a 240 size jet in it. Since I bought it I have gone down to a 230 jet, and a 220 jet. I'm still having the same problem though with blowing through spark plugs. Are my jet sizes still a bit too high, or is it my idle mixture screw that needs to be adjusted? Any help would be appreciated. Thanks.

    10 comments
    • Yeah the guy I bought it from had put just about every performance part on the machine he could. I'm thinking about getting some jets tomorrow from my dealer. I'll see if they have anything under a 160. I might get like a 150, 155, 160, and a 165 just to see what happens.

    • Just about every part in the motor mods section I have in my engine. This is a scanned article from an old dirt wheels atv magazine.

    • Okay sounds good. I really appreciate the help

    • I have a 400 ex carb with after market exhaust with cam I'm running a 155 with a vented lid on my air box

    • Hey thanks Wooly Booger, the 150 jet was spot on after I made a few adjustments. It doesn't take off as quick as it used to, but there's now more chugging, and I don't have to worry about blowing through spark plugs anymore lol

    • Okay sounds good, I'll give her a try and see how it goes.

    • What spark plug do you use? I think the manual says to use a DR8ES-L spark plug. I wasn't sure if you were using a hotter one

    • I actually have one of those calfab swingarms!

    • Do they have a vintage picture of the X it was on?

    • No unfortunately I don't :(