Flywheel Testing

Message

Speed 1B · #1 Post by **Speed 1B** » Wed Nov 14, 2007 9:47 pm

Tim and myself are looking to test out some flywheels next time at the dyno after my new motor is built over the winter. I have been doing some research on the trxs and yfzs and there is no clear choice as to how much lighter they are going...they are just either using -2, -4or -6.

Im wondering if anyone would be willing to donate some cracked or even good flywheels for this project. We would need at least two but preferably 3. If no donations or even someone wanting to sell cheap, its to buying new ones just to cut up and who knows if they will even work? This is just another small step to finding more horsepower in our motors.

Thanks.

Brady

Also i will pay shipping for all people interested in donating.

cannondale27 · #2 Post by **cannondale27** » Thu Nov 15, 2007 12:22 am

Could just take the magnets out and wiegh difference.It must be a good amount and would send you in right direction.If you want we can test this again but Wistech already did.

wayneschofield · #3 Post by **wayneschofield** » Thu Nov 15, 2007 12:58 am

Be careful how you remove material. There is very little support for the outer steel annular ring which is cast into the alloy part. Machine one apart, you'll see what I mean.

I do have a lighter version of the steel flywheels to test but I doubt there's going to be a measurable difference, especially when you look at how much relative inertia the crank has.

Speed 1B · #4 Post by **Speed 1B** » Thu Nov 15, 2007 1:51 am

QUOTE (cannondale27 @ Nov 15 2007, 12:22 AM) <{POST_SNAPBACK}>

Could just take the magnets out and wiegh difference.It must be a good amount and would send you in right direction.If you want we can test this again but Wistech already did.

Tim and i already talked about that but how do we know what made the gain...no magnetic force or lighter weight?

Sandstorm · #5 Post by **Sandstorm** » Thu Nov 15, 2007 4:52 am

On the two Yoshi 450z's Buddah and I have one has a -16 and the other a -10. Now stock they weigh 60 ounces.. You can feel the lighter flywheel rev faster and longer. Both machines are ported by DAB though a few other minor things are not constant like carbs, jetting, but you can feel the difference when you hammer down... Now on the Athena 434Z the crank isn't stroked like Yoshimura does and it revs **** fast and had identical hp numbers to the Yoshi's.. I have the dyno graph of all three layed over each other..

cannondale27 · #6 Post by **cannondale27** » Thu Nov 15, 2007 1:16 pm

QUOTE

Tim and i already talked about that but how do we know what made the gain...no magnetic force or lighter weight?

Just remove the stator.Magnetism wouldnt be a factor then.

I was always told flywheel wieght wont affect HP just how its delivered.Not sure about that.

wayneschofield · #7 Post by **wayneschofield** » Thu Nov 15, 2007 5:45 pm

QUOTE (cannondale27 @ Nov 15 2007, 01:16 PM) <{POST_SNAPBACK}>

I was always told flywheel wieght wont affect HP just how its delivered.Not sure about that.

Power produced by the motor won't change but, when doing an accelerative tests, is allows the energy that would have been put into flywheel as kinetic by accelerating its mass up to speed to be output from the motor instead. It would be easy to actually calcluate it.....

Work out the polar moment of inertia and then calculate the energy difference between a flywheel spinning at your start rpm and the energy in the flywheel at finish rpm. Take start from finish and that is the net difference in energy levels. I can't be bothered to do the measurements and maths myself on what is probably a moot point TBH.

I bet it's too small to be able measure on the dyno though....... just have a good poo before you ride.....

jesshamner · #8 Post by **jesshamner** » Thu Nov 15, 2007 7:38 pm

I agree with Wayne. It doesn't seem like it would be enough to worry about unless you are going all out. And then you might as well look at weight reductions and such for final real world hp.

The acceleration aspect sounds pretty cool though. I like to go fast and the quicker I get to top speed, the better.

wayneschofield · #9 Post by **wayneschofield** » Thu Nov 15, 2007 8:19 pm

QUOTE (jesshamner @ Nov 15 2007, 07:38 PM) <{POST_SNAPBACK}>

I agree with Wayne. It doesn't seem like it would be enough to worry about unless you are going all out. And then you might as well look at weight reductions and such for final real world hp.

The acceleration aspect sounds pretty cool though. I like to go fast and the quicker I get to top speed, the better.

Weight reduction has become something of an obsession for me (even down to a Ti shock body), however, I'm using a heavier than stock flywheel.....

kdeal · #10 Post by **kdeal** » Thu Nov 15, 2007 9:13 pm

QUOTE (jesshamner @ Nov 15 2007, 02:38 PM) <{POST_SNAPBACK}>

I agree with Wayne. It doesn't seem like it would be enough to worry about unless you are going all out. And then you might as well look at weight reductions and such for final real world hp.

The acceleration aspect sounds pretty cool though. I like to go fast and the quicker I get to top speed, the better.

The issue is drivability. A lighter flywheel will be hard to lug around slowly say thru a tight trail. It would be easier to stall the bike. I have run very light flywheels on Banshees previously and can atttest to the rev factor. If you were running a race such as a drag race, where you do not top-out it would definitely be quicker if you got out of the hole cleanly. If you are leaving in 2nd gear now, you will be leaving in third with a drastically lighter flywheel. If you guys are interested, you should look for a way to mount the pick-up sensor closer to the crankshaft and go with a small diameter flywheel (like 3" OD) to get the ultimate affect.