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New KX500 converted to snowbike owner with some questions
Bcsnowbiker:
--- Quote from: 1901306708 on May 06, 2019, 09:11:18 AM ---I don’t like doing things part ways.
To get more real top end you need to do the whole meal deal. 44mm carb, a couple pounds of aluminum shavings on the floor, re-nic, a real pipe, a real head, crank the timing, and then run good fuel. Do just a couple and you get no real change. The thing can’t breathe in or out. Just doesn’t want to rev. Ya you can get it to 9000 but it won’t be moving any more air than at 5000
Honestly...strap a nitrous bottle under the fender. It’s a pile of work to make decent size changes and without a dyno you are just guessing. I have some boondocker stuff ide practically give you if you are in the Revy area. Start with a small jet to gain maybe 10hp and run straight av. No better bang for the buck, esp if you value your time.
I do a piston every year (barrel of c111) and a crank every 2. Might be overkill but I find they are easier to change when in one piece. Run that Lucas oil stabilizer in your gear oil at 10%. The dumb stuff at Napa sitting on the bench where you turn the gears and the oil sticks to it. I thought it was a joke but some Ice racers turned me on to it. It lasts way longer and my gears all still look mint
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Super good info 👍
Never thought I would get someone so close to home with good info and another kx5. I am in Pemberton but revy is not that big of trip.
I have to rebuild now anyways just bought the bike last January motor was fine then but now there is a little play at the crank bearings.
So I will get the head cut and a decompression valve put in do some porting rebuild crank and replace bearings seals piston blah blah and get it up to snuff.
Any advice on squish/head mods? Porting?
We should definitely talk on the nitrous.
1901306708:
Going on memory I think mine is .062 and made to actually look like a squish band. I run straight c111. Because of the silly angled plug, it’s best to find a fella that has done them before or you’ll pay some extra cash to set up a jig. Lots of guys on here can do it. I had Split second do mine. Used him for years on sled motors.
Mine supposedly had motogp porting from gorr when I got it. It looked like an 8yr old fooled around in the intake with a dremmel. To me the cylinder is not worth touching unless you want to do major surgery. Sure someone will charge you $300 to make it look pretty but it will only be marginally better. My exhaust looks like a sled cylinder, or say the 86 kx500.
As far as timing, I keep increasing and it keeps making more power. Thats my setup though, yours may differ. When I went too far, it would start ticking on the midrange at part throttle. So I went up from 100 motor octane to c111 to solve that. Fixing the head allowed it to make the same power with 4 deg less timing.
If you’re going to renic, consider adding a little more clearance. I do .001 more on the bore and then shave a little down on the piston in a few spots. Gets it closer to the clearance a sled would run. Higher loads longer and high cylinder temp variations means you’re more likely to scuff. Hope that info is usefull. Glad to help. Any other questions let me know.
Bcsnowbiker:
--- Quote from: 1901306708 on May 06, 2019, 09:27:08 PM ---Going on memory I think mine is .062 and made to actually look like a squish band. I run straight c111. Because of the silly angled plug, it’s best to find a fella that has done them before or you’ll pay some extra cash to set up a jig. Lots of guys on here can do it. I had Split second do mine. Used him for years on sled motors.
Mine supposedly had motogp porting from gorr when I got it. It looked like an 8yr old fooled around in the intake with a dremmel. To me the cylinder is not worth touching unless you want to do major surgery. Sure someone will charge you $300 to make it look pretty but it will only be marginally better. My exhaust looks like a sled cylinder, or say the 86 kx500.
As far as timing, I keep increasing and it keeps making more power. Thats my setup though, yours may differ. When I went too far, it would start ticking on the midrange at part throttle. So I went up from 100 motor octane to c111 to solve that. Fixing the head allowed it to make the same power with 4 deg less timing.
If you’re going to renic, consider adding a little more clearance. I do .001 more on the bore and then shave a little down on the piston in a few spots. Gets it closer to the clearance a sled would run. Higher loads longer and high cylinder temp variations means you’re more likely to scuff. Hope that info is usefull. Glad to help. Any other questions let me know.
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Very cool 👍
I am replating and I had the same thoughts on a little extra clearance. I also was thinking going for a cast piston rather than forged for less variation in size with the big temp swings
As far as fuel avgas is as far as I will go and I would rather keep it to 50/50 pump/avgas.
I get home again next week and then the motor starts coming apart and we will see where we are at.
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