I want more over rev

[jigggawatt]

I have a low hour 01 500 . I have a fmf gnarly pipe, reed spacer, procircuit 296 silencer. jetting is 168 main and 55 pilot. The bike starts , idles and runs well. I would like more rev. It signs offf pretty early and goes flat. I was thinking of a thicker head gasket . What do you think? I'm not new to 500's , but I've always had red ones. I rode a honda 500 in the Glen Helen 24 hour. I wish now it would've been a green bike , so much easier to ride. Do you think a thicker head gasket is what I'm looking for ?
                                               Thanks,Jim

[Paul]

If you don't get an answer send Doordie a PM. He's got more KX500 secrets than Carter has liver pills.

[gowen]

I have a low hour 01 500 . I have a fmf gnarly pipe, reed spacer, procircuit 296 silencer. jetting is 168 main and 55 pilot. The bike starts , idles and runs well. I would like more rev. It signs offf pretty early and goes flat. I was thinking of a thicker head gasket . What do you think? I'm not new to 500's , but I've always had red ones. I rode a honda 500 in the Glen Helen 24 hour. I wish now it would've been a green bike , so much easier to ride. Do you think a thicker head gasket is what I'm looking for ?
                                               Thanks,Jim

Hi Jim,

I guess it depends on how much over-rev. You can get a thick gasket from Moose and will move more power up top. Also, lose the reed spacer and change it out for a Boyesen Rad Valve, which is excellent for more top-end range.

There are more pricey options too, like shaving the flywheel, or buying a PVL ignition. FMF makes a desert pipe, which moves the power more to the top.

[doordie]

jigggawatt,easiest way is to lower the advance of ignition.
Take away flywheel and move ignitionplate counterclockwise to the last mark.

Raise cylinder makes more rpm and you get higher portimes and lose some bottom.
You have to shave head to avoid "pinging" when you do this.
1,5-1,7mm is safe squish(head to piston at edge).
Use search and type squish...

[jigggawatt]

Thanks I'll give it a try

[gowen]

jigggawatt,easiest way is to lower the advance of ignition.
Take away flywheel and move ignitionplate counterclockwise to the last mark.

Raise cylinder makes more rpm and you get higher portimes and lose some bottom.
You have to shave head to avoid "pinging" when you do this.
1,5-1,7mm is safe squish(head to piston at edge).
Use search and type squish...

I agree with Retarding the ignition. But, I noticed it made my ignition flat, though it did over'rev it just felt like a flat over'rev. Try it out though.

[Polar-Bus]

I have a low hour 01 500 . I have a fmf gnarly pipe, reed spacer, procircuit 296 silencer. jetting is 168 main and 55 pilot. The bike starts , idles and runs well. I would like more rev. It signs offf pretty early and goes flat. I was thinking of a thicker head gasket . What do you think? I'm not new to 500's , but I've always had red ones. I rode a honda 500 in the Glen Helen 24 hour. I wish now it would've been a green bike , so much easier to ride. Do you think a thicker head gasket is what I'm looking for ?
                                               Thanks,Jim

A old skool method for adding revs up on top is to double up on the cylinder base gasket, and run a thinner head gasket. Another trick is to run a flywheel weight which adds max RPM's. A flywheel weight doesn't technically add additional rpm's but allows the engine to rev higher because the added weight has created added rotational crankshaft inertia. I have a Steahly  14 oz. weight and I have a sweet over-rev with no noticable sign-off on rpm's. 

[kx666]

I have a low hour 01 500 . I have a fmf gnarly pipe, reed spacer, procircuit 296 silencer. jetting is 168 main and 55 pilot. The bike starts , idles and runs well. I would like more rev. It signs offf pretty early and goes flat. I was thinking of a thicker head gasket . What do you think? I'm not new to 500's , but I've always had red ones. I rode a honda 500 in the Glen Helen 24 hour. I wish now it would've been a green bike , so much easier to ride. Do you think a thicker head gasket is what I'm looking for ?
                                               Thanks,Jim

A old skool method for adding revs up on top is to double up on the cylinder base gasket, and run a thinner head gasket. Another trick is to run a flywheel weight which adds max RPM's. A flywheel weight doesn't technically add additional rpm's but allows the engine to rev higher because the added weight has created added rotational crankshaft inertia. I have a Steahly  14 oz. weight and I have a sweet over-rev with no noticable sign-off on rpm's. 

correct me if I am wrong, but I have always tried to keep the rotating assembly as light as possible when building for horsepower, allowing the motor to be more responsive and quicker. Adding weight to the rotating assembly usually adds a lot of torque at the expense of top end power.

[gowen]

correct me if I am wrong, but I have always tried to keep the rotating assembly as light as possible when building for horsepower, allowing the motor to be more responsive and quicker. Adding weight to the rotating assembly usually adds a lot of torque at the expense of top end power.

That would be correct, it adds enertia to the low spinning flywheel keeping it moving with little efford (torque) but can't quite spin up due to the weight.. Lame terms, but all the same.

I've never ever kept a flywheel weight. Don't like them. I'm always on the pipe no matter where I ride.

[Polar-Bus]

You light flywheel guys are a stubborn breed Everyone has different needs. I don't have a lot of experience in deep sand, so I won't further comment, but here in New England, and out on the MX track, flywheel weights offer FAR more pro's than con's.

http://www.steahlyoffroad.com/about_steahly.shtml

And heres a bit more  input (although this rider speaks from on road racing opinions):

http://www.ducati.net/faq.cfm?id=44

[kx666]

You light flywheel guys are a stubborn breed Everyone has different needs. I don't have a lot of experience in deep sand, so I won't further comment, but here in New England, and out on the MX track, flywheel weights offer FAR more pro's than con's.

http://www.steahlyoffroad.com/about_steahly.shtml

And heres a bit more  input (although this rider speaks from on road racing opinions):

http://www.ducati.net/faq.cfm?id=44

it really depends on what you are looking to build. jigggawatt  is looking for a pipey bike, lioke a 125 2-stroke, the flywheel weight would makie it ride like a 4-stroke.

[jigggawatt]

I stepped up the main jet and it has helped the top end a lot .  Thanks for the help! I may try a flywheel weight just to get it to hook up. On my
426 the flywheel weight made it feel like a Xr . On my CRF450 a 9oz weight made it hook and feel faster. I wouldn't mind trying 8 or 9 oz's ,but i think 14 would be a little much.

[Polar-Bus]

I stepped up the main jet and it has helped the top end a lot .  Thanks for the help! I may try a flywheel weight just to get it to hook up. On my
426 the flywheel weight made it feel like a Xr . On my CRF450 a 9oz weight made it hook and feel faster. I wouldn't mind trying 8 or 9 oz's ,but i think 14 would be a little much.

A 14oz weight is the only one you can get for a KX500. You can certainly shave the weight if you want, but I found my weight to be perfect for enhansing the KX500's power everywhere in the power curve. Mine still revs quick (just not "violent quick" like stock). Hooks up WAY much better exiting corners, and is a killer controllable wheelie machine now! The great bonus of a flywheel weight, if you don't like it, just "remove" it, unlike shaving the flywheel, if you don't like it your're screwed......