Gx390 flywheel??

[newrider3]

what exactly would you machine off?

i like that theory

It is just that, a theory. You do not want to go shaving down your flywheel just based on that post.

 

[Jeepracer427]

ok. what about the b&s flywheel on it

 

[newrider3]

B&S =/= Honda.

 

[Jeepracer427]

yes i know but it is smaller and lighter. can it be modified. maybe even a gx160 flywheel on it?

 

[newrider3]

Just keep the stock flywheel dude. You said you ride trails in the woods, then you need the torque afforded by the heavier flywheel.

 

[Jeepracer427]

alright yea. i just thought if you got the motor reving higher, it would get you more power and torque

 

[KieranM]

reving higher will give you speed but on the power front, climbing hills and such, you will not see a differance

 

[sideways]

alright yea. i just thought if you got the motor reving higher, it would get you more power and torque

Nope, these engines are designed to make max power at 3600rpm. You'l need a different cam to make more power at higher revs.

Hayden

 

[Russ2251]

Lighter FW does not equal higher RPM.

 

[Jeepracer427]

Lighter FW does not equal higher RPM.

no but according to everyone else that runs these motors, aluminum flywheels=safer high rpms.

 

[newrider3]

You don't need high rpm for offroad trail riding! You want torque, which is almost always highest at lower rpm.

 

[Russ2251]

aluminum flywheels=safer high rpms.

Re-read statement...does not say higher rpm. Engine can only rev so high, has nothing to do with mass of FW.
There is nothing "unsafe" about stock FW unless you plan on going past 10,000rpm.

 

[sideways]

no but according to everyone else that runs these motors, aluminum flywheels=safer high rpms.

That's because the billet flywheels are stronger and are designed for higher rpm, the point Russ was getting at is the common misconception that a lighter flywheel means the engine will get to higher rpm which, of course it wont, it will just get to high revs faster.

Lightening a flywheel is very dangerous as it can considerably weaken the flywheel and possibly cause it to "explode" and thus it is quite dangerous. Think of it this way, say your flywheel is 8" in diameter and your engine is doing 7000rpm, the metal at the edge of the flywheel is effectively doing 167mph, now imagine the kind of damage a large chunk of flywheel going at those speeds could do. Yeah, not pretty.

In reality though a well treated flywheel with a properly torqued nut will not "explode" until extremely high rpm, and to get to such rpm your engine would have to be heavily modified and you would be mad not to have bought a billet flywheel if only for the performance increase. Of course, if you are going to take your engine to high rpm I (and many others) really recommend getting a billet one, just for the safety aspect. You never know if your flywheel has been mistreated in the past or if there is a casting defect ect ect.

Thanks

Hayden

 

[Jeepracer427]

I dont have a problem running the stock flywheel but i dont know what rmps its good to or how long it will last at a high rpm.

 

[Russ2251]

Flywheel is good for something around 10k RPM, far more than your engine can possibly produce.

 

[Jeepracer427]

http://www.oldminibikes.com/forum/engines-modifications/27604-flywheel-saftey-101-a.html


my reason for asking

 

[theo]

I wouldn't go above 6 g's with a stock flywheel.

 

[Russ2251]

First off...that's a clone and not a Honda.
Interesting that history of engine was not posted.
A miss-torqued bolt could have done that.

 

[Russ2251]

I wouldn't go above 6 g's with a stock flywheel.

On a clone maybe, but not a Honda,

 

[Jeepracer427]

ill take your word for it.