Gx390 flywheel??

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KieranM

KieranM

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great advice there kaptain, lighten flywheels should never be done not for karts anyway. best to buy a lighten flywheel if you really want one.
 
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Jeepracer427

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well, i dont have the money for the lightened flywheel but i want to get some power out of it without spending much.
 
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Jeepracer427

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true witch will give me more rpms. more rpms=more speed. the stock flywheel is too heavy for spinning high rpms. will i be able to take the governer off and run it to about 5600?
 
Kaptain Krunch

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Jeepracer427 said:
Ok.
is there any way of reducing the weight of the motor?
Click to expand...

Run it without oil...

No there really isnt any good ways to substantially lower the weight. I wouldnt worry about it though, if you truly want speed, power, and lightness, get a two stroke.
 
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i guess all the torque will be helping me. i have a go kart with a gx160 and aluminum flywheel & 20 over but it is for the woods and trail riding and doesnt have the power.
 
sideways

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Here's what is probably the most informative post on here about lightened flywheels, enjoy!

frederic said:
With less rotating mass, the engine can change it's speed quicker - up or down - from idle all the way to redline where ever that is determined to be. Kinetic energy doesn't get started at any particular RPM. Even at 1 RPM the flywheel is storing some energy. The higher the RPM the more energy can be stored. The more flywheel mass the more energy can be stored. The larger diameter the flywheel, the more energy can be stored. And the slower it will accelerate and decelerate.

How much you notice the difference depends on the power to weight ratio of the vehicle, it's gearing, and so on.

For example. Let us say a mower flywheel weighs 5 lbs, and the engine internals weigh 15 lbs, totalling 20 lbs.

If we shave off 1 lb off the flywheel, we now have 19 lbs, so 1/20, or a 5% difference.

If we're smart and remove that weight from the outside edge of the flywheel, the gain is actually higher than 5% because weight towards the hub is less useful in a flywheel role than weight at the outside diameter. About 6-1/2% increase in acceleration/deceleration capability of the engine.

That means your engine can go from 1000 RPM to 4000 RPM 6.5% faster in this example.

But your kart won't accelerate 6.5% faster.

With a 15 tooth sprocket on the engine and a 60 tooth sprocket on the axle, that's a 4:1 ratio so the live axle would have capability to accelerate and decelerate 1.625% faster than with the original flywheel on the engine, using the same made up example above.

With a tiny engine that's not much of a difference.

On a full size vehicle that produces 500 HP and has a 1:1 5th gear, that is a noticeable difference. In auto racing that noticable difference might be a factor in winning and losing. This is why road racing cars (off-road rally cars, road course track cars, etc) often have short-stroke engines with button clutches. Less rotating mass far from the crankshaft centerline allows these engines to accelerate and decelerate quickly, which gives the driver more control of the car because he/she can shift through many gears keeping the RPMs up in the engine's peak HP range no matter what the speed.
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PHP:

Hayden
 
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