obviously this is just my opinion...

but think about going in the opposite direction....



jmho....Greg

 

I am looking at getting a lighter one so that I can wind it up faster as well.

 

obviously this is just my opinion...

but think about going in the opposite direction....



jmho....Greg[/b]

My understanding is that the heavier the flywheel the slower you build rpm's, which is great for woods riding because once the heavier flywheel is up to speed it tends to keep turning due to the fact it has more mass, which means less stalling. But a lighter flywheel, less mass, revs quicker but will stall out easier. This does not matter to me because for a dune application you are pretty much on the gas anyway.

This is all based on what I've read and it makes sense to me, however, I have not tried it. I am anxious to try it, so if anyone knows of a lighter flywheel or has tried it with positive or negative results, please let us all know.

Thanks

 

all I can offer is my experience in this matter.... and I have quite a lengthy past in racing a wide variety of venues....

but here is what works.... the lighter flywheel will obviously allow the engine to rev up QUICKER... especially when sitting in neutral....(kinda like a 2-stroke).... however, lighter flywheels also tend to reduce the engines ability to rev HIGHER... due to the loss of rotational mass which assists the engine in actually rotating.... remember... a 4-stroke rotates two times... and has 4-strokes.... for each firing/power stroke.... it is the WEIGHT of the rotating mass that allows the engine to continue to turn... (we are not talking about a 2-stroke here, which fires during each revolution).....

so in MY OPINION.... if you are looking for a more solid HP build, that can actually rev higher, w/o the loss of power due to the pulses of the engine...I would go for heavier fly.... and I could care less about engine stalling qualities....trail riding... or how fast my bike can rev in the GARAGE in NEUTRAL..... I only care about she runs at the track.......

however....if I was building an engine that I needed to shift from low rpms and run thru high rpms...on a constant basis... such as a MX bike.... which needs to be able to operate from relatively low rpms... 4k and rev up thru 10k... then a lighter fly might be the way to go..... but a drag bike... which starts out at roughly 8k and only revs from 8k to 10-11k....and you need as much HP as possible at THESE RPMS....especially a hill shooting bike that tends to stay in one gear for quite some time.....w/o much variance in RPMS..... I would want the heavier flywheel.... for its ability to smoothen out this cycle and deliver more power at a steady rpm....

obviously this a fine line..... if you already have a lighter CRF style fly...such as in the 06/newer machines... going lighter will probably not help...and can be detrimental.....sometimes heavier is better...

but if you have the much heavier 04/05 fly.....and race MX... then you can certainly benefit from a lighter fly.... but going too extreme in either direction is detrimental as well....

again...jmho....Greg

 

all I can offer is my experience in this matter.... and I have quite a lengthy past in racing a wide variety of venues....

but here is what works.... the lighter flywheel will obviously allow the engine to rev up QUICKER... especially when sitting in neutral....(kinda like a 2-stroke).... however, lighter flywheels also tend to reduce the engines ability to rev HIGHER... due to the loss of rotational mass which assists the engine in actually rotating.... remember... a 4-stroke rotates two times... and has 4-strokes.... for each firing/power stroke.... it is the WEIGHT of the rotating mass that allows the engine to continue to turn... (we are not talking about a 2-stroke here, which fires during each revolution).....

so in MY OPINION.... if you are looking for a more solid HP build, that can actually rev higher, w/o the loss of power due to the pulses of the engine...I would go for heavier fly.... and I could care less about engine stalling qualities....trail riding... or how fast my bike can rev in the GARAGE in NEUTRAL..... I only care about she runs at the track.......

however....if I was building an engine that I needed to shift from low rpms and run thru high rpms...on a constant basis... such as a MX bike.... which needs to be able to operate from relatively low rpms... 4k and rev up thru 10k... then a lighter fly might be the way to go..... but a drag bike... which starts out at roughly 8k and only revs from 8k to 10-11k....and you need as much HP as possible at THESE RPMS....especially a hill shooting bike that tends to stay in one gear for quite some time.....w/o much variance in RPMS..... I would want the heavier flywheel.... for its ability to smoothen out this cycle and deliver more power at a steady rpm....

obviously this a fine line..... if you already have a lighter CRF style fly...such as in the 06/newer machines... going lighter will probably not help...and can be detrimental.....sometimes heavier is better...

but if you have the much heavier 04/05 fly.....and race MX... then you can certainly benefit from a lighter fly.... but going too extreme in either direction is detrimental as well....

again...jmho....Greg[/b]

Never thought of it that way, but makes perfect sense. Nice write up.

 

Heres the way Ive always seen it work......

Imagine a swinging pendulum..... Its harder to stop one that weighs 100 lbs than it is to stop one that weighs 20 lbs. Having said that, its also harder to get one moving.

A heavy flywheel should be used for woods riding because when it get tight in the corners, that heavier pendulum helps the engine keep momentum and keep from stalling out. Heavier ones are also better for drag racing due to the fact that they keep more momentum when the clutch gets dropped on the starting line and will actually help the engines keep the RPMs.

A lighter one should be used only for things like flat track racing where max RPM's are in consideration and MX. They come in handy in MX to help rev faster coming out of the turns where the bike usually already has some RPM's built up, but these are useless in drag racing.

 

Heres the way Ive always seen it work......

Imagine a swinging pendulum..... Its harder to stop one that weighs 100 lbs than it is to stop one that weighs 20 lbs. Having said that, its also harder to get one moving.

A heavy flywheel should be used for woods riding because when it get tight in the corners, that heavier pendulum helps the engine keep momentum and keep from stalling out. Heavier ones are also better for drag racing due to the fact that they keep more momentum when the clutch gets dropped on the starting line and will actually help the engines keep the RPMs.

A lighter one should be used only for things like flat track racing where max RPM's are in consideration and MX. They come in handy in MX to help rev faster coming out of the turns where the bike usually already has some RPM's built up, but these are useless in drag racing.[/b]

So, what you're saying is I need a new pendulum?

I knew it.

 

index.php?act=findpost&pid=661198

Heres the way Ive always seen it work......

Imagine a swinging pendulum..... Its harder to stop one that weighs 100 lbs than it is to stop one that weighs 20 lbs. Having said that, its also harder to get one moving.

A heavy flywheel should be used for woods riding because when it get tight in the corners, that heavier pendulum helps the engine keep momentum and keep from stalling out. Heavier ones are also better for drag racing due to the fact that they keep more momentum when the clutch gets dropped on the starting line and will actually help the engines keep the RPMs.

A lighter one should be used only for things like flat track racing where max RPM's are in consideration and MX. They come in handy in MX to help rev faster coming out of the turns where the bike usually already has some RPM's built up, but these are useless in drag racing.[/b]

So, what you're saying is I need a new pendulum?

I knew it.
[/b]

Motosport Outlet has them on sale right now......right next to the green and purple powerbands. :sweatingbullets:

BTW, shocks are great......the Axis doing OK?

 

Motosport Outlet has them on sale right now......right next to the green and purple powerbands. :sweatingbullets:

BTW, shocks are great......the Axis doing OK?[/b]

hahahaha thats awesome man. Yeah I really like them, I got some fourwerx carbon guards for them and a piggyback style clamp to put them on the shock, they look sick. Havent got to jump yet.

 

i think lightened flywheels have their place but 80% of the public really don't need one. I think for a hillclimb specific bike, it could be a positive.

 

Do not forget how a flywheel will effect traction.

In the sand, I pick paddles around my build.

I would not expect the quad to climb faster or feel better just by adding a lighter flywheel.

Traction is Key, and Spinnin aint winnin.

My point is, by adding a lighter flywheel, you will get the tires to spin more, and it will rev to the sky, but it may not go as far as with the old flywheel, and not as fast.

If you were to build a bike for a certain purpose, and then put paddles on it, you could eliminate this problem. But unless you experience lots of bogging going up hills, i would not expect much.

I would also go the opposite way if anything.

-Kip

 

all I can offer is my experience in this matter.... and I have quite a lengthy past in racing a wide variety of venues....

but here is what works.... the lighter flywheel will obviously allow the engine to rev up QUICKER... especially when sitting in neutral....(kinda like a 2-stroke).... however, lighter flywheels also tend to reduce the engines ability to rev HIGHER... due to the loss of rotational mass which assists the engine in actually rotating.... remember... a 4-stroke rotates two times... and has 4-strokes.... for each firing/power stroke.... it is the WEIGHT of the rotating mass that allows the engine to continue to turn... (we are not talking about a 2-stroke here, which fires during each revolution).....

so in MY OPINION.... if you are looking for a more solid HP build, that can actually rev higher, w/o the loss of power due to the pulses of the engine...I would go for heavier fly.... and I could care less about engine stalling qualities....trail riding... or how fast my bike can rev in the GARAGE in NEUTRAL..... I only care about she runs at the track.......

however....if I was building an engine that I needed to shift from low rpms and run thru high rpms...on a constant basis... such as a MX bike.... which needs to be able to operate from relatively low rpms... 4k and rev up thru 10k... then a lighter fly might be the way to go..... but a drag bike... which starts out at roughly 8k and only revs from 8k to 10-11k....and you need as much HP as possible at THESE RPMS....especially a hill shooting bike that tends to stay in one gear for quite some time.....w/o much variance in RPMS..... I would want the heavier flywheel.... for its ability to smoothen out this cycle and deliver more power at a steady rpm....

obviously this a fine line..... if you already have a lighter CRF style fly...such as in the 06/newer machines... going lighter will probably not help...and can be detrimental.....sometimes heavier is better...

but if you have the much heavier 04/05 fly.....and race MX... then you can certainly benefit from a lighter fly.... but going too extreme in either direction is detrimental as well....

again...jmho....Greg[/b]

Thanks for the input.....maybe that's why trailtech quit making the lighter flywheel for the 2006 450r's like ours.

I only ride at the dunes and do a lot of hill climbs.....so my thought was lighter is better, but like you say maybe (just like anything) you can take it only so far.

Just the same, if someone knows of somebody who makes a lighter flywheel and it's only around $100 or so (as was the trailtech) I think it would be worth the money to try and put the theory to the test

On a side note I noticed that you are running a #168 main jet. Do you run at sea level? Have you tried different sizes? The reason I ask is I am running a #175 main jet with similar upgrades and I run pretty much at sea level. My upgrades are as follows:

ESR air box eliminator kit
Venom 12.25:1 piston
Stage 2 hot cam
Valve & head job
Full Dr D system
HRC needle and + 1000 rmp wire kit (all that's left from kit)

So if I lean out the main jet, do you think I would gaing more power? Someone told me that with 4 strokes you want to get as much fuel down them as possible.

Sorry to change the subject.......I guess I'm jacking my own thread.

 

well.....others may disagree.... but a #175 on your 06? machine.... is probably a bit too rich....

and whoever told you to cram as much fuel down a 4-stroke as possible......is obviously someone I would stay away from... sorry...

first.... lets talk about the issue... and this is Air to Fuel ratio.... which is 'stoich' or optimum.... at varying ratios depending on each and every machine..... my particular machine likes it in the 14.2:1 or so range.... even though most dyno graphs have a dotted line in the 13:1 range...(way too rich for my blood...but so be it).... bottom line is this.....and take it however you want... but...

TOO many people believe bigger is better.... they believe by gutting their pipes...and needing a richer jet... they are actually burning more AF mix and making MORE power... when USUALLY... nothing is further from the truth... truth be told... when you gut a pipe...or reduce a standard amount of back pressure..... you throw off the engines ability to SCAVENGE fuel.... meaning you REDUCE the Ve (volumetric efficiency of the engine)... this causes a drop in SUCTION (for lack of a much longer description) at the carb signal... this drop is suction.... forces one to increase the jet size in order to compensate for a poorly aspirating engine..... basically... because the suction is so low.... it NEEDS a larger jet...just to get enough fuel into the system to burn correctly....... this low amount of suction or draw or signal.... combined with a larger than needed main jet (if correctly ported and tuned)... makes for very poor performance.... but the person putting those larger jets in believes he is making MORE POWER... again... usually just the opposite.... irregardless of the nice sound coming out the end... the performance is sacrificed....

people get too caught up on 'my bike needed a #170 jet'... well my daddy runs a #175 jet... well my daddy runs a #180 jet... so his bike must be faster.... etc. etc.....

dont get caught up in the numbers...or bragging about this jet or that jet.... jetting has only ONE purpose.. to make the bike perform at its PEAK..... anything less than that is a waste...... and no... 4-bangers do not need to run extra rich for PROTECTION... or to ensure she is not TOO LEAN...... again... another myth....... no one running with a completely removed air box lid.... and minor mods...... running anything in the #150 or above range jets...is running anything close to how lean she was from the factory..... think about how many people have removed their lids....and never even re-jetted... cuzz they heard this rumor or that rumor...or just wanted the engine to 'breath' better....but failed to re-jet.... did the bike instantly blow up? no...... but probably is running way leaner than it should be..... and in short time the rider will notice this, ask some questions... and figure out they need to jet up quite a bit.... but again... there is a far cry between running an open intake with #120 main jet.... vs running the same intake with a #160 or #162 etc.....

you cant really compare your jetting to mine cuzz I am running a taper bored 42.5mm carb...... with different main air bleed jets, etc..... but my best 'guestimate' on your setup would be that you could go down at least 10 jet sizes..... and feel a noticeable gain in power... especially in the upper rpms...upper gears.... she probably feels a bit sluggish once she starts to rev out in 4th and 5th gear... as if she is taking too long to reach the limiter..... try a #162/165 at most...and see what happens...



for those of you still wondering about the lighter vs heavier flywheel....... think for just a moment about this...

if you have a kicker.... remove the auto decompressor..... and see how much energy is expended just trying to kick her over.... IF you even can...... now ask yourself this question..... what part of the engine compensates for this tremendous amount of pressure to overcome a 14:1 squeezed engine? and the answer is.... the rotating MASS..... now multiply that initial KICK by 10,000 times... and this is the energy required to keep that engine rotating for one minute at 10,000 rpms......... just think about how much that extra weight on that flywheel HELPS to keep the engine turning over.......especially at higher rpms..... the more weight you have... the less fall of RPM is discovered between the POWER stroke.. and the COMPRESSION stroke..... this is what allows this engine to rev HIGHER....and have more HP at a given RPM...than a lighter flywheel.... the lighter flywheel will allow the engine to reach a specified rpm FASTER than a heavier flywheel......but once you have reached a specified rpm...it is the HEAVIER fly... that will continue to rev HIGHER and HIGHER....using less and less HP to do so... therefore more HP is applied to the rear wheels....and not used up simply trying to maintain these RPMs.....



jmho....Greg

 

We just lightened up a flywheel for 04/05 bikes, and will try it out on our 04 race bike when we hit the dunes in a couple weeks for the ORG ride. We have the equipment to balance and lighten now! :rock:

I will be lightening the flywheel on my 05 KLX110 too, since those little buggers have a heavier flywheel than our 450R's do.

Anyone have an 06 flywheel they wanna sell so we can run some experiments?

 

Greg, thanks for your input, I'm going to get a #165 & #168 jet and see what happens. Always looking for more power.

 

our 400ex was definately slower after running a lightened flywheel. i had gt thunder do the work so i don't think it was poor quality.