Maintenance & Technical > KX500 Original

Kx500 snowbike more power!

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big green:

--- Quote from: sandblaster on July 05, 2017, 11:08:28 AM ---3rd gear is a weak spot.
It's not that the gear is inferior to other bikes... its that the K5 is a animal and 3rd gear is really the first gear that you can hook up and get that power to the ground. While you are in the trans, replace all the snap rings.... Also, measure your shift forks, many are way out of spec. You can't get new ones but you can get yours repaired.
The Wossner is a superior quality rod.
If you are going to mod the K5 better seriously consider it.
If your running stock, the stock rod will work great.
Wiseco pistons went through a long period of low quality.
However, if yours has been up and running for a while then no worries.
Jason at JT Engine Works, operates from my shop  :lol:
I can tell you this, there are few and far between builders out there that have the eye for detail, the K5 knowledge, and the ability to put it all together in the way that Jason does at any price.
But I say, shop and compare.
Get a quote from all parties..
Get it in writing what they plan on replacing and with what.
Often it's what is not included on a quote that will get you....

--- End quote ---
Well said!

Apetty:
Minor update: I haven't called Jason yet, but I do plan to hopefully in the next week or so. But I ended up buying a blown up 06 Kx250f for 300. I keep kicking around the idea of a af conversion. My original plan was not to do an AF conversion, but for 300 bucks I figured I could keep it around for awhile and maybe I'll get motivated enough and I could almost sell the cases and make my money back for that. But anyways I've been trying to research how to do this as much as I can but have a couple questions. Does the swing arm pivot bolt line up? Also does anyone make some kind of a kit or parts you could buy that might get you half the way there or so? Anyways if I get serious I'll start a new thread about this in the AF section. Just debating if it is worth my time because the snow is coming fast!!!

1901306708:
So i've been through the last years or so on a service kawi kx5 snowbike. i have at my disposal a pipe builder with a dyno, and a really good cylinder guy.

Stock, the cylinder will simply not flow any more air. you can't make much more torque and you certainly can't make it rev. You can fool around with reeds, pipes, heads etc and make the cylinder look pretty. this will get you to about 62hp at most.

now if you know a good cylinder guy, you can make a bunch more power. but you need to make drastic changes. but then the stock pipes wont work very well. you need a real pipe, bigger carb, open up the reed boot as wide as you can etc etc and things start paying off. mine is around 80 horse @ 8200rpm with tq just under 50 for quite a long rpm range.

For snowbike application
-you need to heat the carb with coolant. you probably know that already.
-also the piston clearance is too tight for snow application. couple reasons...rapid heat/cooling when the cylinder is packed with snow, and longer periods of high load.
-thermostats are a good idea but take some fiddling.
-the pvl ignition is good and gives you 80w of power to run a light. stock, mine made the most power at 26 degrees. most guys say thats too much. most guys dont have a dyno. use good fuel though. the pvl ignition will also fry and the slightest sign of water. learned this lesson many times. once its been wet, the next time it gets hot it will fail 100% of the time. you need to silicone it up real good for it not to leak..like unbelievably well.  if you fix the head to something reasonable, then 20 degrees is about where you want to be.

if you want anything more specific let me know. tks

Apetty:
Update: finally some headway. Been talking with Jason from JT Engine works and I'm going to send my engine off to him! From talking with him I got the impression that he has forgot more about the kx500 then I'll ever know. Still not sure exactly what we're going to do to it but for sure porting, big bore, crank rebuild balance, transmission gone through, new clutch basket and clutch etc. very excited to see how this turns out. In response to the last reply it is always awesome to hear from another kx5 snowbiker. I was thinking of going with the new electric start from pantera which comes with the pvl ignition but from your comments I'm alittle afraid. I don't want a finicky system. The last thing I want to do is get stranded in the back country. Have you had many problems with your pvl or what do you think of the e start? I'm running a Lectron carb with an avid carb heater setup with thermostat which worked great last year. I've heard a tunnel cooler works better but so far no problem for me. I'm also running a gnarly pipe does it pay to get a custom one?

sandblaster:
With what Jason and I have discussed that he is thinking on your build, YES... a bigger pipe will be required to get the performance you need.
Also, what size is the carb?

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