I have learned alot from all of your comments regarding the rev limter on the Z400. This issue exists on the KFX400 also. There seems to be no real soultion to this problem except breaking down and spending some money and time on the quad. Available options as I see it.

1. Install a Dyna Tech(or any other for that matter) electronic ignition which ups the rpms by approx. 1500.
2. Switch the CDI box from a DRZ400 bike to the Z400 /w other mods of course.
3. Find a damn good mechanic, pay him well, and tell him "make my Z400 the fastest mother f'er around".

 

Not ENTIRELY true. The Z is geared very well for aggressive riding. If you shift from 2nd to 3rd before, I mean JUST before the rev limiter you're not going to bog. Because you end up squarely in the middle of the torque curve. If you shift too early on a severe hill you may end up in thrid gear below the needed torque and "bog", but shifting back to 2nd won't put you against the rev limiter at that point (it physically can't from a 3rd gear bog). I know what you're saying, but if you ride it hard and are shifting at a high enough RPM (just shy of limiter) all is good. Changing gears in that scenario won't help, if anything it would make matters worse. Unless of course you just wanted a longer gear and had no intention on going to third. (or what ever gear was next). Smaller front sprocket is going to be better for hill climbing 9 out of 10 scenarios. Revs stay up and gear changes rob you of less power.

 

As the point Z400Gramps, I think was trying to make. The most power out of the quad is at the peak torque, over revving may sound cool but what has anyone gained from it? These people that want to go above 9000 rpm, have you done any internal motor work to make it bullet proof? Get to know your torque curve with whatever accessories you have, I do not believe these accessories have moved the peak torque above 9000. I could be wrong but I doubt it.
[img]i/expressions/face-icon-small-confused.gif[/img]

 

freakazoid,

That's part of the point. If you do get internal modifications what do you do to increase the Rev limiter? Change out the CDI? Add an Electronic ignition? At stock the RPM sweet spot at the highest HP is about 7500 rpm. Of course you lose HP at 9000 on a stock Z but there is a time and place when you need those RPMS even thought they may be less effective then the 7500 RMP area. Example:
You're climbing a mother of a hill when there is no way you can shift during the climb but you need to keep the tires spinning to get to the top.

 

Freak you definitely have the righ idea, (no way the ideal torque or HP is at the top of the RPM range) but you do need to get the RPM's above that if you want to be in the torque's 'G' spot AFTER upshifting. I totally agree with most all of the posts, it's just a matter of how you want to attack it and your riding style...ME? I just shift before hitting the rev limiter. It seems easy to me, but others wil disagree.

 

This looks like it will never end! LOL!!!

pdiddy and freak and some others seem to understand. If you modify your motor internally such as a big bore kit that does not mean that you have effectively raised the torque curve! The Z motor is already over square and makes very useable torque well below 9000rpm. It will if tuned properly increase the amount of torque.

If you have the money I would reccomend having your motor built by a Proffesional as most of them will have access to a Dyno and they can give you a print out of the torque curve and better yet you could ask them to install a shift light that is calibrated so that it flashes when it hits the "G" spot! I am serious and not trying to make fun of anyone! I would rather spend a portion of that money for smaller mods and gear and then use the reainder to pay my mortgage!

The other point is that as much as I Love my Z it does have it's limits and for me they are way higher than I will ever know! But what the hell I am having a blast banging gears especially broadside coming out of a turn!

 

I love this Quad as well but I've hit the limit and I want more. I think that this Quad has a lot of potential to become an awesome bike without all the extra maintenance that comes with a two stroke. [img]i/expressions/face-icon-small-happy.gif[/img]

 

Yo Gramps! What up? I thought we ran this subject into the ground. Beat the proverbial dead horse, so to speak. I keep getting the e-mail notifications....and.....I......can't.....stop.... .post.....ing![img]i/expressions/face-icon-small-happy.gif[/img]

 

When you add aftermarket pipe and get it breathing this quad revs to the moon so much faster than stock. The rev limiter seems to come on so much faster, so by short shifting to stay in the SHORTER sweet spot, the 15 toothed racer will easily out pull the short shifting- rev limiter kisser consistantly. We've been down this road many times with the CRF450 quad: run taller if you have the sac to pull it , which it does. Quick rev to tap out on the rev limiter so soon gets frustrating. If you add a least the pipe, the 400 will easily accomidate the 15 tooth front sprocket and pull very hard and QUICK! Just ask some of the 400EX racers{which is mx'ed more than most others}, they go 1-2 teeth taller in the front TO RACE!!! My quad is much faster in a drag than with the STOCK gearing{which is fine for the stock motor} . This green machine is one of {4} LTZ400 and KFX400's I've owned and the 15 tooth is the best solution for the quicker reving modded 400. You won't be disappointed . Spend a few bucks and ride WFO! By the way, I sold my Lonestar CRF450 quad because I am very impressed with my 400's. My modded green machine would run right with the CRF450 quad{even without the big bore kit}. These 400's can easily and quickly pull 15 tooths. Just try it, you'll like it.

 

OK RODSQUADS I'll try it. My Z is a helluva lot quicker after the mods. (I'm new to the ATV scene) With street bikes these mods are noticable, but the damn things are so fast to begin with it's not AS noticable. The Z's motor in stock form didn't impress me (supsension did), but after the mods it really woke up and it's rather quick now. I don't mind having to get out of the gears quicker, but if we've traveled down this road before with the Honda boys and figured out the gearing...well...I'm all for it! I did post that racers gear their bikes for the track, (i.e. longer straights, short track, hills, etc.) and I'm assuming they have more done to those bikes than mine. (full pipe, jetting, intake) So if you say the torque is enough to pull 15 quicker than 14 (it's feasible when traction is concerned), let's go to the next question. Is it easy to do? Do I need to use my gear puller? Is it more complicated than that? Add a link to the chain? I don't need a step by step I'll figure it out, but if putting air in the tire is a difficulty of 1 and a complete motor rebuild is a 10 where does changing the front pulley land? Thanks for the info!