How to build an @ss whooping KX500

[manco]

Ok so uhm yah, I want to build an @ss whooping KX500. I want the kx500 to have no purpose beyond seriously injuring, maiming or killing its rider. I want the power delivery so harsh that when the bike is stopped running at idle tears are slowly falling from its rider's eyes because the rider is quite sure as soon as the carburetor slide opens even a slight amount that the bike will literally flip a 360 degree cartwheel before riding a 100 yard wheelie with or without its rider. I want a bike that can go from putt putting along on the trail to, "OMG did you see that dude on the trail with the KX500? He was riding like 4mph then all of a sudden in about 20 feet of space the bike flipped a cartwheel & accelerated to like 90mph before smashing into a tree. That dude was so F'ed up a helicopter flew in to take him to the hospital. The KX500 is still imbedded in the tree!"

I know this all sounds extreme especially since a stock from the factory KX500 can pretty much accomplish this & install within in its rider all such fear & expectation. Thing of it is pretty much every advertisement, article & forum thread I have read about tuning KX500s as well as a majority of aftermarket parts seem to go in the opposite direction. This thread I hoping will turn out different. F' smooth throttle response, gradual power delivery and top end speed. I want all the horsepower to be delivered ASAP in relation to RPMs. I want to be standing over my KX500 with tears in my eyes as I barely crack open the throttle and watch my arms get ripped off while the KX500 flips a cart wheel & rides away with my dismembered arms hanging limply from the handlebars with fingers in a death grip still firmly attached.

To give you an idea where I am going with this KX500 build here are some of the things I am planning to experiment with for my KX500:

1 Throw the reed block to cylinder spacer in the trash.

2 Toss the flywheel weight into the trash along with the previously mentioned block.

3 Experiment with various pipes.

4 Experiment with various silencers.

5 F' up some pipe by creating various sizes of expansion chamber.

6 Screw with the air box.

7 Experiment with smaller then OEM carburetors. (Not gonna help top end I understand but will help with flipping a 360 from a dead stop. Go do some 2T homework if you don't know where I am coming form.)

8 Look into boring and sleeveing the OEM cylinder with a cast iron liner to increase friction and therefore low end torque with the penalty of heat at high rpms. (Again 2T homework time if you don't understand.)

9 Modify the stator plate to allow ignition timing changes.

10 Look into custom CDIs.

11 Contact Eric Gore and other such builders capable of porting a 2T cylinder for something other then "smooth power delivery."

12 Look into eliminating the power valves to create a more powerful fixed power band based at a certain RPM.

13 Pray the lord my soul to take.

I am not sure where I am going with this build besides straight to hell more then likely. I will be checking back to this thread now and again to add what details I can of my progress, unless of course I am seriously injured, maimed or killed by my KX500 during the course of my work. Any input that anyone has that can help me in achieving my goals of b̶e̶i̶n̶g̶ ̶s̶e̶r̶i̶o̶u̶s̶l̶y̶ ̶i̶n̶j̶u̶r̶e̶d̶,̶ ̶m̶a̶i̶m̶e̶d̶ ̶o̶r̶ ̶k̶i̶l̶l̶e̶d̶  building an @ss whooping KX500 would be greatly appreciated.

[manco]

In all seriousness below is an actual dramatization of the approximation of the dyno chart of the KX500 I would like to build. Note that the "@ss whooping KX500" dyno curve delivers HP sooner at the cost of max HP and at the loss of high rpm HP. This, as informed 2T tuners know, is how it goes when a 2T tuner, "Robs Paul to pay Peter." so to speak in relation to moving the powerband up and down the RPM range to gain advantages at lower RPMs. (If you don't understand this now is the time for that 2T tuning homework.)

[manco]

[sandblaster]

Hey Manco.
If I were you I would start with this engine build:
http://www.kxriders.com/forums/index.php/topic,8717.0.html

Study the pictures carefully.
Once you have completed that, read this article.
http://www.kxriders.com/forums/index.php/topic,12120.0.html

There is so much to say on the how's and what you could do but reading those two articles will give you a real good start.
Then, if you have specific questions, post them up.
We will help you break something the best way we can 

[manco]

Hey Manco.
If I were you I would start with this engine build:
http://www.kxriders.com/forums/index.php/topic,8717.0.html

Study the pictures carefully.
Once you have completed that, read this article.
http://www.kxriders.com/forums/index.php/topic,12120.0.html

There is so much to say on the how's and what you could do but reading those two articles will give you a real good start.
Then, if you have specific questions, post them up.
We will help you break something the best way we can  

Yikes almost 60 pages in those articles. A quick glance and I saw a bunch of info. I guess I am gonna be reading a while. Thanks for the tips. I will start going through the threads this week.

[manco]

Continuning my brain storming list from above here are some more areas I am gonna look into.

15 Flat slide vs Round slide carbs

16 Softer reeds for more opening at low rpm

17 Lower vs higher compression

[tecate3]

In ’84, Honda introduced a bike so vicious, it has gone down in the annuls of all-time ground-pounding terror machines. With a powerband that jumped from 20 horsepower to 50 in the course of 500 rpm and a shock unsuitable for a 125, controlling the explosive 500R required a delicate touch and nerves of steel.

[manco]

True that about the early Hondas. I recently picked up an 81 Honda CR250r with blown motor. I am looking into swapping in a CR480r engine. From what I have read quite a few of the early big bores had two operating modes, blubbering or exploding which were separated by an 1/8" of throttle twist.

[RoostiusMaximus]

better yet, i have a CR450 engine without a home. its a direct bolt in to the cr250 frame you have. you'd need your carb/reed/electrical for use on this engine.

[RoostiusMaximus]

no to get too far into this without pointing out something obvious, the reed spacer is the best thing you can do to help what you're looking for. Or a VF2 reed. Ignition shouldn't be a big deal, run the old small flywheel stuff.
In the CR we were lucky, the 84-86 engine was a 139mm rod so the rod ratio made the engines response evil quick. 1984-85 also had the lightest flywheel and most degrees of timing compared to any other cr500.

[manco]

The 450 was the other engine I had in mind. They are a bit rarer though so I was looking at 480s which are still commonly found. Do you know about the electrical parts between the cr250 & 450. Stator & rotor are completely different between the bikes it looks like. The coils between the bikes are compatible I know. Do you know if the CDIs can swap between the 250 & 450?

I may be interested in yer motor. I guess message me if you are thinking of parting with it. I am not sure if I am ready to get into the cr project yet but who knows I guess. My shop is ridiculous right now. I got a Yamaha that always runs, two basket case dirt bikes & some misc. spares cluttering everything up. I need to cut down on the junk & get a few things ripping this winter. Maybe I'll take you up on the 450 motor when the floor clears in front of my tool box.  

[manco]

I will look into the vf2 reed n spacer when the engine is up again.

Interesting stuff on the CR motors. I didn't know about the stroke change.

The lighter flywheel for the KX is that the pre-1992 generator you mean or which years is lighter?

Speaking of years of engine on the CR reminded me, I wanted to ad to this thread, Would an older engine provide this performance better then a newer KIPS engine? for example an 1987 engine vs a 1998 engine.

My 98 engine I need to rebuild or replace is how I brought this thread up looking for ideas. I been seeing lately though low dollar 1987, 88 KX500 bikes with running motors. I thought about just buying one & slapping the old motor in my 98 frame for a cheap get the bike back on the dirt kind of repair. If the older 87-88 engines had certain performance advantages maybe I would consider the option of an older motor more thoroughly.

[manco]

Something else I have been thinking about what I am after may not be just about about engine tuning for lower rpm HP. It might also be about shifting the rpms up in relation to the mph that bike is traveling. What I might be more after might be better described as "more HP at lower speed."

If I could shift the gearing way low to allow a lot of HP at say 5mph that is what I am after. So far I have been thinking low speed, low rpm, higher then normal HP with normal gearing. The other way to get ther at the same time may be to be thinking lower speed, higher rpm, higher hp. Only way a kx can get there would be lower gearing. I have looked so far into rear sprockets as to find anything up to 60 tooth. I am running I think 13  x 52 now. 13/52 is still to high for what I want. Bigger then 52 though and the lower rear chain guide needs modified. I already have an 18" rim. Its running a big tire so its pretty much like a 19 mx setup. I could run a low profile tire to gain a little lower gearing. I did look into various years of kx500 gearing. I don't think I rememeber any big sweeps is gear changes year to year.

One thing I have been wondering is are there any other lower geared primary gear & clutch housing sets compatible with kx500 engines? I did some looking but don't remember seeing much. Kawasaki only shows that the 89 and newer kx500 have the same primary gear & share it with the kdx250. What about kx125 or 250 primary gears? Will those swap into a KX500? Wonder what there gearing is.

[RoostiusMaximus]

The CR stroke was the same 1984-01, the con rod length changed which inverted the piston speeds, spark advance taht was required, flywheel mass needed etc.

I've read what you're saying about riding slow, in reality you're chasing torque 

On the CR I'm running 14/51 with the 140 M5B tire, can start on a gravel road at 1500-2000 rpm in 5th and not stall it, then roll on the throttle and blister the tire. Bike idles under 700 rpm and I've been known to ride it as low as 500 rpm.

Primary gear is written in stone on the KX. On the CR the large gear on the basket got smaller in 2009 crf450's which is the same mounting pattern, so if a crank and waterpump gear were made to compensate you could have a taller primary gear, I know its opposite of what you're hunting, but that is the only ability available.

[tecate3]

here is an unfinished 84 CR500 in an 86 Tecate project:
https://seattle.craigslist.org/oly/snw/5228276522.html

If the CR500 motor fits in the Tecate then it fits in the KX500, how the sprockets line up is another question, maybe some one will ask the seller.