kx500 power opinions

[jfabmotorsports.com]

thats a sad story ,but to be realistic 
an aged pretty stock k5 delivers about 58 HP

a modded fresh 250 goes up to 50 HP or more
take the riders weight and skills ,there you go

it can be true in other words i think 

220lbs K5 + 200lbs rider @ 58 hp = 7.24lbs/hp
210lbs ??250 +170lbs rider @50 hp = 7.6lbs/hp

You may have something wrong but if his tire is better than yours or if he has anything newer than a 1990 anything 250 2 stroke it will have a lot better traction than the K5. If he has 52.5 hp, and he could, you are even hp/weight and your but is kicked.

[jfabmotorsports.com]

WOW Mick, I was writing my post and you beat me to it. You said a mouth full. I race mx and everything you said is true. I can get the power of the KX500AF to the ground but it is because of the modern geometry, holeshot device 15/50 gearing and a million practic starts....as you said.

JFAB

[Mick]

Yeah I've spent much more effort trying to get power to the ground than I have spent trying to increasing it.  Holeshot devices, good tire selections, a wide rim and strangely enough even a CR250 ignition have all increased my AF's performance more than any cylinder porting could ever have done.

[tharden]

I am running a 120x90x19 tire.  I think my gearing is one of my problems.

[Mick]

14/48 gearing is definately not the prob fo sho.

...it's a rider problem 


practice, practice, practice...

[DoldGuy]

Tharden,
I agree that a rider can make a huge difference, BUT, there is NOT a 250 2 stroke that can hang with a 500 (red, green or orange) that is running properly (& geared correctly). I have a 250 drag bike that is pretty quick (it will run any 250 with just a pipe & reeds) & my STOCK K5 will MPH it in 300'. The 250 is lowered etc for this & the 500 is not so the 250 is quicker because of this, but if you add another 100' it is all over, the K5 ( or red or orange) will go by. I haven ridden 250's most of my life and they have plenty of power for most all situations, but if you drag a 500, and you get into 3rd gear the 500 is gone, I know this as my buddies had the CR500's and we would practice our starts from the gate on a MX track every week & it happens just like I mentioned.
Now let's try to get you whipping up on ALL 250's. Think of John Force running a 10.5 slick,  his times would not be there as he is just spinning his tires, it sounds you are doing the same with the current gearing you have (adding teeth to rear is a torque multiplier) as the motor is over powering the traction available, digging a trench, not moving forward. Now take away some of that torque and spread it out longer you will obtain forward motion longer between gears. Try a 15 tooth counter shaft ( it's in expensive) to confirm you are on the right path & let us Know.

[tharden]

I agree I am not the best rider but I seem to loose by the same margin every time.    I will try the counter sprocket.  Also,  is two cycle oil suppose to pool up in the boot in between the carb and air filter?  I have not been home to look at the reeds, but I think they may not be sealing right.

[kaw rider]

That sure would be blowback, pull the reeds and check them.

[Mick]

You sure it isn't oil oozing off your filter after a cleaning???

I've seen ALOT of riders put the oil on too heavy, I'm guilty of doing this on occasion myself.  Generally it just runs down into the airbox, but I've seen riders put it on so generously it ran into the carb as well.

[tharden]

The air filter oil I use is red, but the oil in the air tube was green like the Golden Spectro.

[KX500freak]

thats a sad story ,but to be realistic 
an aged pretty stock k5 delivers about 58 HP

a modded fresh 250 goes up to 50 HP or more
take the riders weight and skills ,there you go

it can be true in other words i think 

220lbs K5 + 200lbs rider @ 58 hp = 7.24lbs/hp
210lbs ??250 +170lbs rider @50 hp = 7.6lbs/hp

You may have something wrong but if his tire is better than yours or if he has anything newer than a 1990 anything 250 2 stroke it will have a lot better traction than the K5. If he has 52.5 hp, and he could, you are even hp/weight and your but is kicked.

im with you here, i too say what mick also says,and you ,that any recent 250 can outrun a k5 as described above .

[Dutch-K5 Fan]

In holland you ride KNMV or MON. They are the 2 unions to choose from KNMV is the biggest and connected to the FIM.
You start lokal than district, junior, national, Dutch championship(ONK). Than you can go euro championship and GP's If your good enough

I've ridden Junior 125 races and combined 250/500 on a cr250. I was about 15 to 23 place of 45 riders Top 10 could ride
top 15 national.

One race in memory of a friend I raced the top class with ONK riders Johan Boonen(ex GP) on his SXS540 even GP rider Mark de Reuver on his full factory sxf250 and many more fast riders. Some with 500 2strokes. I hole shoted It with my self tuned 2000 cr250 wich wassent the fastest ride.

Why Could I do this? Good luck or good rider???    Don't know


A good K-5 can beat everything, a AF  even beat the factory 450!!!  Seen steafn Everts do this by MILES!!!

Dutchie

[gwcrim]

I once beat a Kawasaki ZRX1100 with a Harley Sportster 4 out of 5 times at a drag strip.

The other guy had no clue how to launch on a christmas tree.  By the time he left, I had 4-5 bike lengths on him.  The one time he beat me, I pulled a red light.  I would have won that race otherwise.

Not that you aren't a good rider, but as in most racing, it's 90% racer, 10% vehicle.

[tharden]

Well this is what I came up with.  The reeds and KIPS valves are working well.  After I cleaned my air filter I did not spray as much oil on it.  I then removed the flywheel weight.  After I removed the flywheel weight I could tell a big difference.  The bike does not vibrate near as much.  Before removing the weight while riding at low rpm the bike would vibrate a good bit and I could feel it trough the pegs.  Now it is much smoother.  As for starting the bike I could not tell a difference, and the bike idles the same.  The biggest difference was in power delivery.  I could not believe it.  Before I was able to sit close to the tank and gun the bike at a stand still and keep the front tire from rising up too high.  Now I have to learn how to really ride the bike.  I tried to do the same thing and I liked to have gotten thrown off of it.  Really impressed.  I also did not see any loss in torque at low speed either, and it still lugs good at low speeds.  I believe since the weight is removed the engine can spin up quicker and the tire can deliver better traction.

[DoldGuy]

Tharden,
Removing the weight allows the bike to spin up RPM much quicker, getting into the Torque of the motor. If you were "Digging a Trench" before, it will happen even more without the weight. I still think you need to go up a tooth on the counter  & try your cousin again.  I seriously doubt a whatever year YZ250 with pipe, wiseco piston, head chambered is anywhere close to the 50 HP mark ( they produce about 44 @ the wheel stock / depending on who's Dyno) and nowhere near the Torque of a 500. It sounds as you are happy, & I reckon that's all that really matters.