I have a 87 zilla with fmf pipe/silencer and a k&N filter.
the engine has good compression.
The bike is running like crap,I got beat by a cr250,yz125,and Raptor, all four of us raced at once the raptor won,then the 250,125,and my zilla came in last.
The guy on the raptor said I should have raped all of them in that race.
So there is somthing up with my bike!!!
Does anyone know the proper jetting? I should be the fastest!
Thanks!!!
matt.

 

I have the same bike but with a uni filter. I have to say that when I come back from a ride, my arm hurt from hanging on! How does your spark plug look? It should be tan, not black. If it's black then you are too rich. One thing that you also have to do is improve air flow to your air box. Either remove the cover to let more air in or drill some holes in the cover and put in those 1" filterd vents. This is what I did with great success.
I have a keihin carb and running a 178 main and 68 slow. Hope this helps.

 

fmf told me the stock jetting is recomended with their pipe and silencer(420 main 30 pilot)but should i get a 430 main and put the clip in 3rd position with the K&N? the jetting in the bike now is 450 main,30 pilot,needle clip in 2nd position from top it was in 3rd but running way to rich so i droped the needle.
what is the stock needle clip position?

 

Mikuni has different jett sizes than my Keihin carb. Your numbers don't mean anything to me. The way you check jetting is by checking the plug's color. By putting on a pipe, silencer and K&N you will be passing more air but not more gas so you should defenately re-jett to avoid running too lean. If you're too lean you WILL seize youre engine!!!!!! Remember to punch some holes in your air box to improve performance and re-jett (more air needs more gas=more power)

 

Stock jetting for a 87 is 440 and 35.

 

What gets me is that a Raptor beat a CR 250. What a joke! I do believe that a Zilla should be faster than a Raptor, but a CR 250? This bike will smoke any quad. I am not talking about top speed, but getting there. Anyway, for the problem at hand, I can not tell you about jetting by you telling us what bike beat you. If you tell us what you mean by "running like crap" we should be able to get it close.