Maintenance & Technical > Kx Frankensteins
KX500 shifter kart build
Polar-Bus:
I've been thinking about attempting this project for years, and seeing as how with my hip arthritis being to the point I can barely swing my leg over the seat of a dirt bike, rather than sell my KX500, why not steal the mint running engine and stuff it into my CRG shifter kart !? Here's a few pics of my CR125 race kart :
The first issue is the drive sprocket. I need a KX500 spline and a 428 pitch sprocket and nobody makes one. So time to get crafty !
I machined an arbor fixture and machined the OD of a standard KX500 sprocket :
Then I bored the ID of a new CR125 kart sprocket (428 pitch) to mate with the KX500 sprocket. I chose an 18T for now as I generally like a 16T with the 125 engine so I should be in the ballpark.
And problem solved ! I now have a custom KX500 428 pitch drive sprocket. Here?s a pic of the sprocket all welded.
So the next phase is the engine mount and exhaust pipe. I currently have some leads on local to me custom exhaust fab shops. I want a clean fitting and functional pipe, and the OEM KX500 pipe simply won't work by design. I'm also going to dig my 500 out of storage this weekend and yank the engine. This project is gonna be INSANE :-o when i'm done ! I need to do some caculations on gearing and does anyone know what the upper rpm range of a KX500 is ? I'm taking a guess that peak around 7500 rpm's ?
RoostDaddy:
Have you looked into any of the Outlaw Kart exhausts? There are a few that do them for the KX500, but not many. May be what you're looking for as the fit should work for you and I'm sure you already have a silencer.
I believe most bikes peak around 6500 / 7500 max. over-rev (with the exception of a few)
Brute:
Having raced karts for some years, This would be insane. Fun, but insane. Finding a sprint track long enough to stretch the legs out would be a problem. Maybe it would be best not too! What kind of top end are you gearing for?
Polar-Bus:
--- Quote from: Brute on January 27, 2012, 11:36:30 AM ---Having raced karts for some years, This would be insane. Fun, but insane. Finding a sprint track long enough to stretch the legs out would be a problem. Maybe it would be best not too! What kind of top end are you gearing for?
--- End quote ---
I put all the KX500's gearing ratios into my Excel gearing caculator and looks like I need to gear about 18/24 this will theoretically pull 130 mph @ 7000 rpm. Which in the real world should pull about 115 ? Seriously how fast would you want to push a KX500 kart ? The chassis was specifically engineered for a 125cc engine so all the corner weights will now be way off with the heavy 500 engine. However I plan on adding lead ballast to help bring the chassis back to reasonably balanced. I'm really curious to see how this kart will handle as well as stand your hair on end when whacking the throttle ! LOL
Motorrad:
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