so i am looking for extremely cheap ways to get better performance out out of my 01 400ex. right now it is bone stock. how much difference will changing the front sprocket to a tooth higher and the rear 2 teeth lower affect performance. acceleration wise, speed wise, and hill shooting wise. also i eard a rumor that putting a brake block off on your machine acts as a rev limiter and lets your machine rev a little higher, is this true?? also if anyone has any tips or tricks please feel free to share.

thanks in advance

Nic

 

The gearing changes you are considering will <u>significantly</u> raise your gearing.....

You will lose low end power and throtle response, overall torque, and be slower off the line. What you will gain is top end speed (and speed isn't the definition of "power" in my book!). The ratios you are suggesting are appropriate for fast wide open riding, like in the open desert. It will make it miserable on a tight eastern woods trail, or steep hillclimbs where you really need torquey power.

If it is stock I would start with the basic engine mods, like opening up the airbox, air filter, and an aftermarket exhaust, and of course a rejet. After that, then you can start messing with your gear ratios, if you must.

 

It difficult to give you any constructive advice in gearing without know what you mean by "better performance". Gearing changes are strictly robbing Peter to pay paul. Your just converting the available engine power to one of 2 things. Speed....or acceleration.

The only way to offset the negative results of a gearing change (loss of top speed or acceleration) is to provide that gearing with more engine power. You will not gain significant enough engine power increases from inexpensive mods to offset the "rob Peter to pay Paul" problem.

There no better way of putting it. Big Power increase = Big Money. Little power increases = Little money.

 

well i am not really worried about losing 5 mph top end for a little extra acceleration because i dont really ride anywhere that i am gonna race or even open up my machine to all out top end. i just want to be a little quicker up the hill and have some more acceleration. i have already decided to by a new K&N air filter with outerwear and i definelty think thet will help a little bit. and i still havent decided if i want to raise my back srpocket 2 teeth when i drop the front 2 teeth. so what do you think? any input is greatly appreciated.

 

Then, like reconranger said, you are backwards on your spocket changes. You need a larger rear sprocket and/or smaller front spocket. Depending on the sprocket teeth number, changing 1 tooth in the front is about like changing 3 in the rear. So the change your talking about would be like a 5 tooth change. That is a MAJOR ratio change.

 

It's kind of hard to tell from your desctiption, what you are really trying to achieve???? Your definition of what "power" means to you, is not at all clear! Sounds like you want a more torquey throtle response (acceleration) and you said you don't mind losing some speed on top....so raising your gearing is the opposite of the way you want to go!

Remember: 1 tooth change in front = 3 teeth in back. Going smaller in front and/or larger in back, will LOWER your gearing. Going larger in front and/or smaller in back, will RAISE your gearing. And, tire size changes will change your effective gearing too!

My experience with the 400EX is that going down 1 tooth in front was to much. The EX has a strong, torquey bottom end to begin with, and lowering the gearing had my front end off the ground all the time (even with 22" Holeshot XCT rear tires). It actually made me slower, because I couldn't power out of turns because the front end would come up and lose steering control.

My EX is my woods trail quad, so I want it geared down a little, but not so much that it is wheelie happy. I am currently running 1 tooth larger in the rear (this gears it down a little), and 20" Holeshot XC tires.

Here is what I would try......front sprockets are cheap (like $12). Get one that is down one tooth, and get one that is up one tooth (but only if you have enough chain length!), and try them out. Experience is the best teacher, and this will show you what the differences are like (but the changes will be extreme, in my experience). Once you decide if you want to gear up or down, you can fine tune the ratio with changes to the rear sprocket.

 

he is saying that he wants to accelerate faster. going down on the front or up on the back would do that. in his sig it says you have a 14 tooth front sprocket, that is one down. maybe a 39 rear sprocket would be enough. sounds like its time for an exhaust or more though.

 

Think of it this way:

In order to accelerate more quickly, you need to make it easier for the engine to gain RPM's. By decreasing the number of teeth on the front sprocket, the engine has to move 1 less tooth per revolution. Thus, less chain to move. That means it will be quicker.

A simliar result will be achieved by increasing the number of teeth on the rear sprocket.

Higher top speeds require the opposite. A higher number of teeth on the front sprocket means it will move more chain at the same RPM.

Keep in mind that things like traction, motor power, the rider's abilities, etc., will all affect the final results.