Tri Z carb advice NEEDED!

[Dynofox]

I decided to tear into my carb today to try to figure out why my Z doesn't want to rev out. Everything looked good in the carb, and all the jets were clean. I noticed it has a 440 main do you guys think thats too big? I'm running a full dg system, boyesen reeds, and the bike is being ridden at 800ft elevation. It starts up first or second kick everytime, has a killer mid range punch, and never fouls plugs. Both reeds and uni filter are brand new, and i'm running klotz 32:1. The problem is while going through the gears when I get much past 3/4 throttle it doesn't pull hard anymore. Any advice would be great!

[J.D.]

I would certainly say that's your problem. Stock jet is 470(that's what mine is at, I live at 3,000 elevation) and topend is good, but no low end. With all those mods you may need to go more than 470, but put in a 470 and see how it acts is what I would do.(This going by what the Yamaha dealer told me, go back to stock carb and work off of things from there.)

Which brings up a question from me. My spark plug is more on the black side than on the "caramel/chocolate brown" color. What exactly does that mean?

[Dynofox]

Thanks for the advice, if your plug is black after a high speed run that means your main is to large.

[J.D.]

Could this be the reason for no low end power? Because even in neutral, if I crank it all the way back it bogs for about a second and a half, then it picks up....could it just be sending too much fuel into the cylinder before it get's a chance to burn it?

[84250r]

Which brings up a question from me. My spark plug is more on the black side than on the "caramel/chocolate brown" color. What exactly does that mean?

Your running to rich,causing it to lose performance in your low end.

[J.D.]

Interesting. So I should start taking my main down one step at a time until I have better low end, but still have my topend and whatnot,right?

[Dynofox]

I'd go down a size if I was you and then check the plug. If it's still really black try going down another. BTW to check the plug make a high speed run in top gear and while your on the gas still turn it off and check the plug. P.S. I took my Z to a friends large hay field that is wide open and after making a few runs it revs out nice now. I think it just needed to be opened up for more than a short section. I went riding today and it ran great, the more I ride it the more I like it!