Good mod or snake oil? Anyone tried one?

[RNL]

http://www.amrracing.com/catalog/honda/honda-trx400ex-cdi-rev-box-32.html

[CJM]

The only ones that do anything are the dynatek and old white bros. I tried a procom and it actually made it run worse.

Save your money on bettert hings Id say.

[RNL]

The only ones that do anything are the dynatek and old white bros. I tried a procom and it actually made it run worse.

Save your money on bettert hings Id say.

I was just curious, it says it advances the timing, I know thats a mod a lot of guys do with the sparks key.

[Drifterboy3]

Link didn't work. What is this stuff?

[beastlywarrior]

Here's a quote I like to go by

Anything you need to know about timing advance

The ignition system on your car has to work in perfect concert with the rest of the engine. *The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.

When the fuel/air mixture in the cylinder burns, the temperature rises and the fuel is converted to exhaust gas. This transformation causes the pressure in the cylinder to increase dramatically and forces the piston down.


In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke. Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success.

There is a small delay from the time of the spark to the time when the fuel/air mixture is all burning and the pressure in the cylinder reaches its maximum. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.

To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke, so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful work.

Work = Force * Distance

In a cylinder:

Force = Pressure * Area of the piston
Distance = Stroke length
So when we're talking about a cylinder, work = pressure * piston area * stroke length. And because the length of the stroke and the area of the piston are fixed, the only way to maximize work is by increasing pressure.

The timing of the spark is important, and the timing can either be advanced or retarded depending on conditions.

The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance: The faster the engine speed, the more advance is required.

Other goals, like minimizing emissions, take priority when maximum power is not required. For instance, by retarding the spark timing (moving the spark closer to the top of the compression stroke), maximum cylinder pressures and temperatures can be reduced. Lowering temperatures helps reduce the formation of nitrogen oxides (NOx), which are a regulated pollutant. Retarding the timing may also eliminate knocking; some cars that have knock sensors will do this automatically.

[RNL]

Here's a quote I like to go by

Anything you need to know about timing advance

The ignition system on your car has to work in perfect concert with the rest of the engine. *The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase.

When the fuel/air mixture in the cylinder burns, the temperature rises and the fuel is converted to exhaust gas. This transformation causes the pressure in the cylinder to increase dramatically and forces the piston down.


In order to get the most torque and power from the engine, the goal is to maximize the pressure in the cylinder during the power stroke. Maximizing pressure will also produce the best engine efficiency, which translates directly into better mileage. The timing of the spark is critical to success.

There is a small delay from the time of the spark to the time when the fuel/air mixture is all burning and the pressure in the cylinder reaches its maximum. If the spark occurs right when the piston reaches the top of the compression stroke, the piston will have already moved down part of the way into its power stroke before the gases in the cylinder have reached their highest pressures.

To make the best use of the fuel, the spark should occur before the piston reaches the top of the compression stroke, so by the time the piston starts down into its power stroke the pressures are high enough to start producing useful work.

Work = Force * Distance

In a cylinder:

Force = Pressure * Area of the piston
Distance = Stroke length
So when we're talking about a cylinder, work = pressure * piston area * stroke length. And because the length of the stroke and the area of the piston are fixed, the only way to maximize work is by increasing pressure.

The timing of the spark is important, and the timing can either be advanced or retarded depending on conditions.

The time that the fuel takes to burn is roughly constant. But the speed of the pistons increases as the engine speed increases. This means that the faster the engine goes, the earlier the spark has to occur. This is called spark advance: The faster the engine speed, the more advance is required.

Other goals, like minimizing emissions, take priority when maximum power is not required. For instance, by retarding the spark timing (moving the spark closer to the top of the compression stroke), maximum cylinder pressures and temperatures can be reduced. Lowering temperatures helps reduce the formation of nitrogen oxides (NOx), which are a regulated pollutant. Retarding the timing may also eliminate knocking; some cars that have knock sensors will do this automatically.

See I think some people say the timing doesn't do anything because they think it adds power. Thats not the idea, it improves the response and "snap" of your motor. Right?

[beastlywarrior]

Right the goal is to make the flame front reach the piston at slightly after tdc. Advancing the timing allowed you to do so, sooner than stock. Also motor with a more advanced ignition timing tend to move more towards lower end and retarded moves towards upper. A good timing curve will advance more than stock at lower rpms then move closer to the stock point as the rpms build

[slightlybent47]

The ex falls off very fast on the top end so there very little power up there anyway.
If you want more snap then do other mods instead.
Most of the power is in the head, or lack there of.
A good port and polish with a pipe and carb mod will do a lot more for ya.

[KKiowaTJ]

I like to keep it around 7-8500k rpm, Best peak power. I stopped reading when it said 'removed limiter'. That's just asking for trouble no matter how fast you can pull the string or kill it. So far stock has not failed me yet. To each their own

[JOHNDOE83]

The ex falls off very fast on the top end so there very little power up there anyway.
If you want more snap then do other mods instead.
Most of the power is in the head, or lack there of.
A good port and polish with a pipe and carb mod will do a lot more for ya.

There is massive amounts of power on the top end of a 400ex!!

If your falling off and plaining out on the top end you might need more main jet or something else is possibly holding you back.

It should rev out fast and hard from idle to wot without any hesitation or plaining out.

[2001400exrida]

There is massive amounts of power on the top end of a 400ex!!

If your falling off and plaining out on the top end you might need more main jet or something else is possibly holding you back.

It should rev out fast and hard from idle to wot without any hesitation or plaining out.

not to argue, but there is a lack of power on the 400ex top end, that's no joke. cam will help a little, but it's not a secret that the 400ex does not have top reve power. The main point that slightlybent is making is that raising the rev limiter by 1000k rpm like these rev boxes do, does not give anymore power, sure you can rev farther, but your hp goes down at those high rpm's, you're better off shifting and using the real power.

[Thumpin440ex]

There was just another thread about this. The CDI boxes on stock bikes normally do nothing. If you have a diff cam, then it can help pull the revs in the top end because the box will allow you to take advantage of the cam. If your looking to pep up the stock bike, add a Sparks timing key. TIMING IS HORSEPOWER.

John

[JOHNDOE83]

not to argue, but there is a lack of power on the 400ex top end, that's no joke. cam will help a little, but it's not a secret that the 400ex does not have top reve power. The main point that slightlybent is making is that raising the rev limiter by 1000k rpm like these rev boxes do, does not give anymore power, sure you can rev farther, but your hp goes down at those high rpm's, you're better off shifting and using the real power.

Oh were deff gonna argue!!!

Nah Im just kidding....lol.

I used to think the same thing, once I figured out tunning and added a few minor mods my 440 was a all out top end bike.

Even after the mods it was still kinda lacking somewhere, once I figured out the proper tunning method my 440 turned into a completely different animal.

Most people think anything over a 175-180 jet is to much for any 400ex, I had a 190 and it was still reving slow and had a lack in the top end. Once I started tunning it using the www.jetsrus.com method, as soon as I went over 205 the 400ex became a all out top end bike like I said before. I made it all the way up to 220 and if a 400ex isnt a top end rpm bike then how do you explain a 440ex doing this.

If a 400ex isnt a high rev motor this guy should have destroyed me! Maybe the valves and cdi helped me out but still theres stock bores on here running less mods "more tunning" hanging with 450s at the drag strip.

White yfz450, lowered, 10 paddle haulers, high comp, ported, piped, carb, camd, with a LOCK UP CLUTCH. "WITH A GOOD RACER"

My 440ex, lowered, 8 paddle haulers, 450r carb, stage 2 cam, cdi, no slip on, open filter, kibblewhite valves, tusk clutch. "with me"

http://www.atvriders.com/vbb/showthread.php?505470-Old-440-drag-racing-video

[2001400exrida]

johndoe - your theory on jetting is a little skewed. jetting does not have to do with rpm's or "top end"......it has to do with throttle position, your main jet is in use even at 3k rpm's or at 5k rpm's if you have the throttle pinned you better believe it's pulling the main jet. That's cool if you think your 400ex is a top end quad, but i'd love to see a dyno of a 400ex that doesn't start to lose power around 8-9k rpm. Feel free to post a dyno of your motor if you think it's still gaining power up at those rpm's.

i still agree with the original point that was made. gaining 1k rpm's on a 400ex does not give you anymore power. You're already out of your peak power rpm range therefore you might as well shift and get back to the power range.

videos are a dime a dozen and impossible to judge any type of power delivery. There are way to many variables, but i will tell you, no 440 will hang with a highly modded yfz. especially a drag yfz with a lockout clutch. Either way, good run, but you still lost, lol

[JOHNDOE83]

[QUOTE=2001400exrida;4350482]johndoe - your theory on jetting is a little skewed. jetting does not have to do with rpm's or "top end".QUOTE]

I understand your concern, it explains this on jetsrus.

The thing is, if theres not enough fuel it will not rev out to its full potential, and if it does it will rev slow and be slightly hesitant but never reach the actual max RPM.

So it actually does have something to do with your top end rpm and top end performance.

I can actually dig up a 440 dyno right now! Its gonna be 400exshops dyno not mine tho.

[2001400exrida]

sure post a dyno where the hp is still climbing at 9k rpm and i'll eat crow.

[JOHNDOE83]

http://www.atvriders.com/vbb/showthread.php?447583-What-Will-It-Do/page3&highlight=400exshop+dyno

Me and exshop used to get alot of bashing, this thread shows it unfortunatly.

[2001400exrida]

haha, so you post a link to fake dyno sheet or one with a nitrous 400ex. Without rpm's on that graph you can't tell the exact range, but it's plain as day that motor falls right on it's face after it hits 60hp. I think everybody else in that thread has pretty much asked all the questions I would have and there has never been proof so I am going to go with the safe assumption that the posted dyno's and information is nothing but a crock of beans.

Let's not turn this into a big mess John the point all along is that the 400ex is not a high rev output machine, and unless you've got crazy mods, gaining 1k rpm will not gain you more horsepower. And putting in a fatter mainjet will not give you more hp at 9k rpm either. You want power at 9k rpm, get yourself a yfz450.

[JOHNDOE83]

haha, so you post a link to fake dyno sheet or one with a nitrous 400ex. Without rpm's on that graph you can't tell the exact range, but it's plain as day that motor falls right on it's face after it hits 60hp. I think everybody else in that thread has pretty much asked all the questions I would have and there has never been proof so I am going to go with the safe assumption that the posted dyno's and information is nothing but a crock of beans.

Let's not turn this into a big mess John the point all along is that the 400ex is not a high rev output machine, and unless you've got crazy mods, gaining 1k rpm will not gain you more horsepower. And putting in a fatter mainjet will not give you more hp at 9k rpm either. You want power at 9k rpm, get yourself a yfz450.

LOL in the vid I posted, aparently my 440 revs just as high and as fast as a yfz...lol.

That dyno sheet was a 39hp dyno, it only went to 60 with his nos shot.

It doesnt show rpms but it doesnt show it falling on its face either, its actually pretty consistant with alot of other dyno sheets from other bikes in the same forum. What your thinking is it falling on its face is actually were the motor peaks out and plateau's and doesnt have any extra rpm.

Unless you go big on jetting and see it for yourself, youll always have a low end overly lean 400ex instead of a high rev motor.

[2001400exrida]

haha ok so everybody should put a 210 main jet in their 400ex because they will instantly get a high rev motor. i'm done with you john doe.

dude i truly hope nobody believes what you type, i might sound harsh, but this is getting ridiculous. Do you really think your 440 revs as high and as fast as a yfz?

you obviously did not read anything i said about how jetting affects power. just because you have a monster main jet doesn't make the machine a high rev motor. THe rev limiter controls how high your peak rpm. like i said jetting is related to throttle position, fuel delivery starts with the throttle, then goes to the carb circuits, then to the motor. You can't throw a huge main jet in there and intantly get yourself a high rev motor. You can build a 400 to maintain power in the high rpm's sure, but typically these motors lack in the red line department.

[Stickman400]

I'll believe Johns word over yours any day of the week Ryan. Most of the stuff you say has got truth to it but not all of it.

[JOHNDOE83]

haha ok so everybody should put a 210 main jet in their 400ex because they will instantly get a high rev motor. i'm done with you john doe.

dude i truly hope nobody believes what you type, i might sound harsh, but this is getting ridiculous. Do you really think your 440 revs as high and as fast as a yfz?

you obviously did not read anything i said about how jetting affects power. just because you have a monster main jet doesn't make the machine a high rev motor. THe rev limiter controls how high your peak rpm. like i said jetting is related to throttle position, fuel delivery starts with the throttle, then goes to the carb circuits, then to the motor. You can't throw a huge main jet in there and intantly get yourself a high rev motor. You can build a 400 to maintain power in the high rpm's sure, but typically these motors lack in the red line department.

Im not sure what your getting so worked up over?

I never said anything that you just stated, you took what I said and made it completely out of context.

I posted the dyno result, I posted the vid of me vs a high mod 450, I thought we were talking and debating not arguing.

Look your NOT UNDERSTANDING what I said about jetting!

I never said that a monster main makes a high rev motor, these motors are all lean from factory. If your main jet is to lean you will not rev as high or as fast as it should and will not get the rpm power in the high rpms, if you rev good and fast but not in the high RPMs then your deffinetly to lean on your main jet. It should rev hard and fast from 0-WOT without hesitation is all I said and thats a fact!!! www.jetsrus.com

Sure the rev limiter controls your peak RPMs, but if your to lean and not even getting close to your limiter or it takes you a half mile before you top out in gear, then your NOT GETTING FULL POTENTIAL ANYWAY.

[ish416]

I have never seen an EX gain power after 8,500 RPM. Regardless of headwork, cam, carb, piston, jetting, etc... These engines are simply not designed for high rpm power.

If you're riding your EX much past 8,000 RPM, you're doing it wrong.

[2001400exrida]

I'll believe Johns word over yours any day of the week Ryan. Most of the stuff you say has got truth to it but not all of it.

Nobody's telling you what to believe man. You're certainly entitled to believe what you want.

[2001400exrida]

I never said that a monster main makes a high rev motor,
you didn't? so i must have read this text wrong....

once I figured out tunning and added a few minor mods my 440 was a all out top end bike.

Even after the mods it was still kinda lacking somewhere, once I figured out the proper tunning method my 440 turned into a completely different animal.
as soon as I went over 205 the 400ex became a all out top end bike like I said before. I made it all the way up to 220 and [B]if a 400ex isnt a top end rpm bike then how do you explain a 440ex doing this.


If your main jet is to lean you will not rev as high or as fast as it should and will not get the rpm power in the high rpms, if you rev good and fast but not in the high RPMs then your deffinetly to lean on your main jet. It should rev hard and fast from 0-WOT without hesitation is all I said and thats a fact!!!

Just so you know, being rich on the main will make your revs very weak and it will have what we call a "false rev limiter". The 400ex running Perfect is not a high rev power motor. I understand everything you are saying. Which is why I reply in disagreement.

My point all along is that these motors do not make more HP after the rev limiter or 8500 rpm therefore as mentioned if you're thinking you're getting power up there you are riding it wrong.

You can twist and turn the facts any which way you want, but it's clear what you've stated and that's where we disagree, no harm no foul, i'm not getting worked up i just don't like seeing BS being shared with people who might take it as a true statement.

[JOHNDOE83]

Being too rich is usually the sign of a false rev limiter. Just saying. And yes you did say that running a bigger main will make it a high revving motor lol as opposed yo running lean and not being a high rev motor. The 400ex running Perfect is not a high rev power motor. I understand everything you are saying. Which is why I reply in disagreement.

My point all along is that these motors do not make more HP after the rev limited or 8500 rpm therefore as mentioned if you're thinking you're getting power up there you are riding it wrong.

lol yall are cool.

Im must deff be riding this thing wrong and my tunning must be way off to acomplish this.

http://www.youtube.com/watch?v=YbxcE9rHt90&feature=channel

[ish416]

Im must deff be riding this thing wrong and my tunning must be way off to acomplish this.

Accomplish what? Accelerating in a straight line? You don't appear to be winning, so, I am not sure what you are trying to accomplish.

http://farm6.staticflickr.com/5469/9964200056_baed19933e_b.jpg

[RNL]

So is there a difference in advancing your timing through the flywheel key as opposed to advanced timing through a cdi?

[DragonGunner]

So is there a difference in advancing your timing through the flywheel key as opposed to advanced timing through a cdi?


Through the flywheel it will give maybe better throttle response, at least I noticed that, but do not think it adds more rpm, nor would I think it changes the
powerband. I had 2 400EX's one with sparks advance timing and the other with a WB cdi.....2 different worlds.

[2001400exrida]

^^agreed. I run the +3 sparks key and as long as you don't have heavy mods it is a very worthwhile upgrade. throttle response and rev power is night and day compared to stock.

[400man]

^^agreed. I run the +3 sparks key and as long as you don't have heavy mods it is a very worthwhile upgrade. throttle response and rev power is night and day compared to stock.

I think I tried one of those keys a few years ago when my motor was stock with a slipon pipe, I don't remember it being much different so I went back to stock when I took my cover back off to get the flywheel lightened. I thought it would make it harder to get the cam timed correctly according to the marks on the flywheel.

[chronicsmoke]

I think I tried one of those keys a few years ago when my motor was stock with a slipon pipe, I don't remember it being much different so I went back to stock when I took my cover back off to get the flywheel lightened. I thought it would make it harder to get the cam timed correctly according to the marks on the flywheel.

I didn't notice a significant difference either, my buddy that builds my engine laughed at it and said it's pointless but he'll put it in anyway.. I did 3-4 mods at once so I can't be sure the effectiveness of it. It was the +3 key, not the +6 that sparks offers(d)

I still have it installed but I think I'm going to remove it and go to stock and add a rev box. Would be nice to see dyno sheets to see the difference..

[2001400exrida]

i wonder if you guys need some jetting adjustments? I know when i put mine it it did make it a little harder to set the timing, you have to go a little past the mark. you guys sure you didn't put yours in backwards, lol. I can say for sure the throttle response was very noticeable. Some say it will cause these motors to run a little hotter,i haven't experienced that yet.

for 15 bucks on a mild build i consider it a worthwhile mod.

[JOHNDOE83]

Accomplish what? Accelerating in a straight line? You don't appear to be winning, so, I am not sure what you are trying to accomplish.

http://farm6.staticflickr.com/5469/9964200056_baed19933e_b.jpg


LOL

Bro, that snap sho is at an angle which appears to have him much further then me, take a snap shot of us directly in front of the camera.

Also like I said, that yfz has high comp, ported, bored carb, lock up clutch, pipe, cam AND 2 MORE PADDLES ON HIS TIRES THEN I HAVE.

In theory he should have walked on me the whole way down the track, but my lil slow revving, non high rpm having 400ex was right along with him in dead even race.

[JOHNDOE83]

Oh were deff gonna argue!!!

Nah Im just kidding....lol.

I used to think the same thing, once I figured out tunning and added a few minor mods my 440 was a all out top end bike.

Even after the mods it was still kinda lacking somewhere, once I figured out the proper tunning method my 440 turned into a completely different animal.

Most people think anything over a 175-180 jet is to much for any 400ex, I had a 190 and it was still reving slow and had a lack in the top end. Once I started tunning it using the www.jetsrus.com method, as soon as I went over 205 the 400ex became a all out top end bike like I said before. I made it all the way up to 220 and if a 400ex isnt a top end rpm bike then how do you explain a 440ex doing this.

If a 400ex isnt a high rev motor this guy should have destroyed me! Maybe the valves and cdi helped me out but still theres stock bores on here running less mods "more tunning" hanging with 450s at the drag strip.

White yfz450, lowered, 10 paddle haulers, high comp, ported, piped, carb, camd, with a LOCK UP CLUTCH. "WITH A GOOD RACER"

My 440ex, lowered, 8 paddle haulers, 450r carb, stage 2 cam, cdi, no slip on, open filter, kibblewhite valves, tusk clutch. "with me"

http://www.atvriders.com/vbb/showthread.php?505470-Old-440-drag-racing-video

This is the post your reffering to 2001400exrida, where does it say a monster main makes a high rev motor?

It says in not so many words that if your lean it will rev slow! And that proper tunning will make it rev faster, which is 100% true.

I guess youll never know until you get more experienced.

www.jetsrus.com

[2001400exrida]

haha johndoe, you win, your 400ex wastes high comp, ported, bored carb, lock out clutch, piped and cammed and more paddled yfz's all day long. we don't believe you but we'll let you win.

john, yes properly tuned you will run at max power. but you should understand being too rich on the main will do the same thing, it will rev slow and it won't hit the real rev limiter. I know for 1 that my 400ex is perfectly tuned with a 175 main jet. I had a 185 in there and was hitting a false rev limiter and did not get peak revs.....so you're theory on just throwing bigger and bigger jets in there is not correct. I'm glad you got your lessons from jetsrus.com. are they paying you to advertise for them? I get my lessons from playing with the jet sizes.

[JOHNDOE83]

haha johndoe, you win, your 400ex wastes high comp, ported, bored carb, lock out clutch, piped and cammed and more paddled yfz's all day long. we don't believe you but we'll let you win.

john, yes properly tuned you will run at max power. but you should understand being too rich on the main will do the same thing, it will rev slow and it won't hit the real rev limiter. I know for 1 that my 400ex is perfectly tuned with a 175 main jet. I had a 185 in there and was hitting a false rev limiter and did not get peak revs.....so you're theory on just throwing bigger and bigger jets in there is not correct. I'm glad you got your lessons from jetsrus.com. are they paying you to advertise for them? I get my lessons from playing with the jet sizes.

Thats not what I said at all but ok.

And actually my theory is correct and not a theory, it says right here www.jetsrus.com and in many threads ive posted in, go big till it stumbles from being rich "your false limiter" then back down until it stops stuttering and fully revs out.

And bro, I posted the vid, that guy is a friend of mine, we just raced at orlando speed world last weekend together, I was fastest quad of the night "on hybrid" he was second fastest, he ran a 3.88 consistently and I ran a 3.65 as my fastest time.

[2001400exrida]

john you know alot of times while a lean condition is not good, you will actually rev faster being lean, it will cut out at the top, but lean is mean in case you didn't know. when you talk about slow revs and not hitting the rev limiter that is a rich condition. lean condition will simple cut out it won't rev slow like you have said, that's called being rich and too much fuel. I had my 400ex a little lean and that thing ripped all the way to the rev limiter but it would cut out ocassionally...it didn't rev slow i can tell you that, lol.

being a little lean makes more horsepower (within reason) than being a little rich. but you run the risk when your'e lean which is certainly not worth it in any case.

[chronicsmoke]

i wonder if you guys need some jetting adjustments? I know when i put mine it it did make it a little harder to set the timing, you have to go a little past the mark. you guys sure you didn't put yours in backwards, lol. I can say for sure the throttle response was very noticeable. Some say it will cause these motors to run a little hotter,i haven't experienced that yet.

for 15 bucks on a mild build i consider it a worthwhile mod.

lol my guy is a pro and builds race winning sidecars and racing street bikes for a living I can assure you it's not in backwards..

Like I said, I probably didnt find it noticeable with the St.2 cam i slapped in at the same time which makes sense because it pushed curve the up in the powerband. I'm taking it out and going to a legit rev box.. maybe I'll take it out and test it before I slap the box back on for a back-back comparison.

All engines are different which is why it's pointless to argue the effectiveness of parts without dyno's or head to head test...

[JOHNDOE83]

john you know alot of times while a lean condition is not good, you will actually rev faster being lean, it will cut out at the top, but lean is mean in case you didn't know. when you talk about slow revs and not hitting the rev limiter that is a rich condition. lean condition will simple cut out it won't rev slow like you have said, that's called being rich and too much fuel. I had my 400ex a little lean and that thing ripped all the way to the rev limiter but it would cut out ocassionally...it didn't rev slow i can tell you that, lol.

being a little lean makes more horsepower (within reason) than being a little rich. but you run the risk when your'e lean which is certainly not worth it in any case.

Yes, see were on the same page its just hard to get all the ins and outs explained correctly while typing online....lol.

The lean and rich we are both speaking of is KIND OF a fine line to walk, it can be to lean and all you see is as a light pop "slight backfire" once in awhile on heavy acceleration a few more increase in jet sizes and that pop will go away and youll be in the "good" lean spot like you want to be in. Or slightly less jetting instead of more around that slight pop will hurt the top end from being to lean and start that slow revving super hot red pipes kinda lean.

I like going to the edge of the rich stumble and backing down 5 jet sizes, according to jetsrus you only go down 1 at a time until the stumble is gone but I feel thats prob were people get and stay slightly rich, backing down the 5 is kinda like being in that slight lean spot that you describe only on the edge of it, so when the weather is warm its slight rich and keeps things cool and safe, then in winter times it leans out slightly but the cold air keeps things running good and safe.

[DragonGunner]

John, how much HP do you think you have, and how much lighter in weight if any do you have over the YFZ? I ask because the Built YFZ should be making way more HP which according to some would make him the automatic winner hands down....which is not always true.

[JOHNDOE83]

John, how much HP do you think you have, and how much lighter in weight if any do you have over the YFZ? I ask because the Built YFZ should be making way more HP which according to some would make him the automatic winner hands down....which is not always true.

400exshop has supoosed 39 hp, mine and his mods are "almost" the same with the exception of him running a fcr and 13:1 compression, and me running 10:1 with a 450r carb and bigger valves.

I would say with the balance of mods Im probally right along with him between 37-39hp...maybe.

The only weight mods I had in that vid was allum struts instead of shocks with the front brakes removed which does save about 30-40lbs

With the ex motor and the yfz if we both have a good start and both shift without missing any gear we are almost a exact match, If i slip up he beats by about a half quad length and if he slips up I beat him by about a tire...lol.

Im not sure on the yfz/400ex weight difference, he didnt have any weight mods done to his yfz.

[2001400exrida]

that yfz with the mods you listed has 50hp minimum depending on the port work of course. your 400ex has 39hp.....that should tell you something right there.

if you weren't in FL i'd love to line up my little 45hp yfz with that high revving 400ex, lol.

[DragonGunner]

that yfz with the mods you listed has 50hp minimum depending on the port work of course. your 400ex has 39hp.....that should tell you something right there.

if you weren't in FL i'd love to line up my little 45hp yfz with that high revving 400ex, lol.


I would say those HP numbers are about right....However the race isn't about a mile long top end as far as it will go race who gets there faster and
farther ahead. In short bursts tight technical woods racing or MX a lower HP machine can still beat a high HP machine.

[2001400exrida]

I would say those HP numbers are about right....However the race isn't about a mile long top end as far as it will go race who gets there faster and
farther ahead. In short bursts tight technical woods racing or MX a lower HP machine can still beat a high HP machine.

that's very true, but when you go to a 300ft drag race you don't see 400ex's, lol you see high HP machines whooping up on people! i undersand about woods racing, i run a 400 and have clobbered some 450's on the trails. you need useable power in the woods and not too much of it either.

[400man]

why don't all you grandmas stop wasting forum space and go ride

[2001400exrida]

haha, oh there's plenty of forum space, this forum could use the activity don't ya think? whether we're arguing about a 400ex high revver or not. I'll be out tonight on the yfz, got a bean field cut that i'm ready to tear up!

[DragonGunner]

haha, oh there's plenty of forum space, this forum could use the activity don't ya think? whether we're arguing about a 400ex high revver or not. I'll be out tonight on the yfz, got a bean field cut that i'm ready to tear up!


Ya they picking beans here now....love the fields, just gotta watch for the groundhog holes!!!!

[beastlywarrior]

Do any of you guys listen to each other instead of *****ing at each other? Did anyone read what I put, it'll tell you everything you need

[2001400exrida]

Do any of you guys listen to each other instead of *****ing at each other? Did anyone read what I put, it'll tell you everything you need

Yeah we read it nobody is debating it. Some guy posted that the 400ex has massive amounts of power on the top end. If you read the thread that is what the discussion is about.