Here is some information on rotating mass. Hope this helps.........

Rotating Mass

 

hah!, I've got a college education, and took a wee bit of upper level math, and that link is freggin greek to me.....hmmm I wonder if anyone can come up with concrete proof of how much a lighter axle will help you on a hill, seeing as the hill is an infinate variable...... who ever does, make sure you post all the equations, to humor the rest of us that can't mathematically solve it.

I can't see how a really good axle could make you 2 bike lengths quicker to the top....?[img]i/expressions/face-icon-small-confused.gif[/img] As soon as someone can show me it really works, I will put one on my yammy.

 

I'm glad you saw the humor in my link.[img]i/expressions/face-icon-small-happy.gif[/img]

What I think is interesting is how so many I run into on the dunes emphasize the axle weight, yet they ride around with full weight flywheels, lol[img]i/expressions/face-icon-small-smile.gif[/img]

 

Mark i dont want you to think that i am getting paranoid about the behavior at the dunes but i will say that it is drastically different in a bad way than it used to be.Most of what i see is a lack of etiquette that most that have been duning for a long time know such as dont line up 12" from someone when you race,hold a tight line up the hill,have some skill at stopping as well as flying up the hill and running past everyone when the race is done( does not mean you won).The alcohol consumed at the parking area contributes in a big way to the behavior that i am describing and i am surprised that it is not more controlled.I personally dont see a huge problem with violent behavior just more a lack of respect and knowledge about what is safe and respectful while at the dunes.

 

Mike,

Thats cool. As far as the viloence, I was more referring to other peeps posts when they brought up that subject. As far as other riders leading up comp hill at the start, I used to see that about 50% of the time or so. When they did, I just usually let them go up the hill without me! LOL. Some start early, and also I just would go around and I wouldnt give them the win. However, after 3 or 4 races usually someone got the nod or gave it; meaning you won or conceded.

I admit that I used to be one of those parking lot drinkers. Im not too proud of it, but never hurt no one either, not even myself (well there was that one time ... ) . Anyways, I've changed a bit on that concept - not that I had to, just that i wanted to - not trying to preach or anything either.

By the way, on another subject, your buddy in Jefferson (shhhhhh) is over here in Utah tonight working on that project of his. You know that special one? Anyways - it came together today for him! I wish I could give you more details. Too bad he wont be able to stay for this Holiday at Sant Mountain. Everyone would have been shocked!

 

Mark yeah i think i have heard there is (someone) from Jefferson who seems to be pretty good at making things go fast.LOL.My original post was maybe not something i should have shared but i was and am hoping that it will make some newer less seasoned riders think just a little bit.That( person) from Jefferson did quite a job on my stock bore DS and once i save more $$$$ i will be talking to him about building a real drag DS with a big bore,light frame and OH YEAH!!!

 

[img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img] this is soo true

 

Is there some kind of inside joke that i am not getting about lightened flywheels?Come on Ron give it up does this really help on a DS or what?I have a lightened flywheel on my 690 Raptor and i think it takes away some low end.I doubt if i would ever spend the money on a lightened axle for my dune quad but i will for my future project.

 

Lightening the flywheel will do three things that I know of.......

1) It allows the motor to rev quicker

2) It significantly reduces stress on the crankshaft

3) It allows the motor to be pulled down from RPM quicker by load

I think it is a myth that torque or bottom end are reduced by lightening the flywheel. I think you get that impression by the following scenario. Picture yourself sitting at the line. You rev your motor up to 7000 rpm and are ready to launch. You dump the clutch and with the full weight flywheel, the rpms drop to say 5500 rpm then quickly climb back up. If you had a lightened flywheel, the rpms might drop to 5000 rpm for arguments sake. You have less torque and hp at 5000 than you do at 5500.........that gives the impression that you lose bottom end. It could even be enough to push you over the edge on gearing to avoid a bog at the line. The upside is that over the rest of the run, you rev up quicker and end up netting a faster run up the hill.

This same comparison works for situations we find ourselves in when we dune and run the off camber stuff. Lets say you are pulling a hill hard and it has a razor back at the top........with a lightened flywheel you will want to get off the throttle later because your motor is going to spin down quicker and no one wants to clutch or stall before you crest the top.

Remember those old tractors from the early part of the century that had those ginormous external flywheels and probably not more than 15 hp, lol? They barely had enough power to spin up the motor but once the motor was at rpm, it didn't matter when the plow pulled through hard soil then hit rocks then soft soil then deeper then shallower constantly changing the amount of load that was put on the motor. The inertia of the massive flywheel evened out the inconsistencies. If it wasen't that way, the tractor would buck and bog and jerk and be a nightmare to try and use.

As good as this was for tractors........it really is the pits for racing. A DS flywheel is around 7 to 7.5 lbs stock. You can take about 3 to 3.5 lbs off it that I know of. Based on the flywheel's relationship with the crankshaft, per pound it has a much greater effect on how quickly the motor can spin up given equal conditions than an axle ever could.

No inside jokes..........just learning[img]i/expressions/face-icon-small-smile.gif[/img]

 

Thank you nut [img]i/expressions/face-icon-small-smile.gif[/img]

I have an experiment going myself.. Do you perhaps have any evedence about the distance the tires are from the carrier? Do you think width of the axle plays a part in the spin up?