You may have seen my comments about lack of low end on the Z. The engine bogs at low RPM, refuses to lug down, and stalls easily. At about 1/3 throtle, there is a hit (not unlike a Banshee) and the power comes on very strong. Anyway, I'm not quite ready to do the K&N and pipe and rejet thing just yet, but to get a little more air in the stock airbox I took off the silly thing that covers the snorkle. Guess what, the low end problem became worse to the point of being TERRIBLE (but high end was not effected).

This leads me to suspect that this is a jetting problem!! The thing is just jetted WAY LEAN ON THE BOTTOM END!!! Manufacturers typically jet lean to meet emisions standards, and this may be what's going on here????

 

I installed a 25 pilot jet in mine and am heading to the dunes today.
When I return I will report the difference.
I have the K&N and pipe already.

 

How do you like the Yoshi?? The dealer had one on one of the bikes out on the floor. It looks pretty sweet. It seems small though, like maybe it would be very loud???

 

I've also heard that a lot of people's plugs were outta whack and way tight. Have you checked that out too?

 

Hey YZGuy what is the altitude where you ride? I wonder if the Cali Z's are a little different than the other 50 states in the tuning department. I had heard that the Raptors were. My farm is at the 1400 foot level in the Mark Twain National forest but when I go riding at lower altitudes I notice mine popping when I left off like it's also running to lean at lower alitudes. I'm considering going with an HMF slip-on with a spark arrestor if I keep the quad. I've been looking at Cannondales.

 

I have a hard time understanding why the z400 would have low end issues because I've ridden the dirt bikes and they have plenty of low end[img]i/expressions/face-icon-small-confused.gif[/img].

 

My plug was OK. My altitude at home is 1,100 ft., but I live at the base of a mountain range that goes up to 12,000 ft, and we also ride the low desert which is below sea level. The highest I have had it so far is 4,000 ft, but can't say I noticed any dramatic differences with altitude change. If lean, it should run better at altitude.

I'm not sure what the vacume operated carburator needle thing is all about?? If I could, I would raise the needle a notch to see if that helped.

 

YZGUY, you need to find someone in your area to compare your Z with. My bro-in-law(who lives two houses down) has a 2002 400EX, so I can swap back and forth between the two. I detect only the slightest amount of torque advantage with the EX.

So either, his EX is a dog, or my Z is abnormally strong off bottom. Or there is something wrong with your Z.

Most guyes are posting that the Z and EX are close concerning bottom end torque. If I were you I would be very concerned that there might be something wrong with that Z.

Good luck,

Later...

 

The Yoshi pipe is loud so I got the TEC kit to quiten it down without much power loss.

 

coolhuh, how much differance does the TEC make? Take a guess, would you say it is 40% louder than stock with the TEC installed? Or what % would you guess.

I want the power without the noise, guess some people want everything!!!

Later...