Maintenance & Technical > KX500 Original

What about 500 vs 250 transmissions?

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Hillclimb#42:
 I ride and race a k5 and a 250. I try to set them up the same as much as possible. Hopefully that will make them both as fast and rideable as possible. I put on the same front and rear sprockets on them, and the 250, believe it or not, pulls the the gear farther. That is to say that, I need to shift the 500 sooner on the same hill. Does the transmission in a k5 have lower gears than a 250 or is the power from the k5 able to reach the top of the gear that much faster? I have been running 13/47 on both, but now have the 14 back on the 500. I think that will feel taller than the 250, but I'm not sure of final ratios or if that even matters. Anybody know the difference between 250 and 500 stock 2nd gear sizes?  :?

BDI:
13/47 Is very low for the kx500.The transmission gear ratio's do matter. All the transmission gear ratio's should be in your manual's at the end of the chapter that talks about your transmission, you do have manual's for your bikes right :? I tried that gear ratio on my bike before. I found that the bike slowed down do to the fact I was turning the tire less times per engine revolution that adds up to less ground coverd at any given rpm not to mention the fact the you have to shift more times going up the hill. My current gear ratio Is taller then stock. I like to gear taller and then make more horse power to pull the taller gear rather than gear down to try to make up for a lack of ponies, you will always go slower and your 500 probably isn't lacking any ponies.

Hillclimb#42:
 I hear what you're saying BDI, and I agree for the most part. I am basically copying other racers on the gearing choice. The object is to run the tallest gear possible with no bog, but a bog on the 500 means you just crashed hard. Understanding that when Hillclimbing the point is not only to make it up, but be the fastest. That means leave it pinned until you are over. On the 250 you have to clutch more to stay off of a bog after a jump, but the stock length 500 wants to flip as soon as it hooks. If you have to let off to regain control, you just lost. I have successfully made the hills, and am leading in points in Indiana and Illinois, but I'm not always the fastest. Of course the 500's fresh motor is not lacking on the power dept., but it seems crazy that the 250 pulls the same gearing farther. Yeah, I have to break out the manuals tonight and see what they say about my gears in tranny. It may actually be better to gear down on back sprocket and pull third out of the hole. I actually just need whatever gear that will spin out of the hole, but one that also pulls on the entire hill without shifting. Also keep in mind we have alot of clay here, which turns hard as pavement with dust on top. Hills often have three breakers on a 150 ft hill. So it is basically three hole shots of 50 ft on average. I'm back to 14/47 and have already been warned by more experienced riders that this may be too tall. So I guess its wheelie time or win time, huh. Thats the only way to race!!!! :mrgreen:

BDI:
I don't hill climb in the way that you do I basicly sand drag up a big sand dune I launch in second and then stab third at the base of the hill grab fourth about one third of the way up and hold it all the way to the top for a smooth ride if all goes right. My bike is loaded and in contact with the ground for the most part. My gearing Is 14/45 and my bike pulls fourth gear up the hill with authority but If any thing happens to cause me to let off my pass is over, so I see your point. Here is a cool tool that takes some patience to use.  .http://www.xs4all.nl/~ator0437/gc/   and this is a ratio chart that might help you make better informed gear ratio changes   http://www.dropbears.com/u/utilities/sprocket.htm   Don't forget your 250 probably turn's more rpm than your 500. If your 250 pulls 1000 rpm more than your 500 it will seam to pull the same gear a lot longer.

gowen:

--- Quote from: Hillclimb#42 on July 12, 2007, 10:53:47 AM --- I ride and race a k5 and a 250. I try to set them up the same as much as possible. Hopefully that will make them both as fast and rideable as possible. I put on the same front and rear sprockets on them, and the 250, believe it or not, pulls the the gear farther. That is to say that, I need to shift the 500 sooner on the same hill. Does the transmission in a k5 have lower gears than a 250 or is the power from the k5 able to reach the top of the gear that much faster? I have been running 13/47 on both, but now have the 14 back on the 500. I think that will feel taller than the 250, but I'm not sure of final ratios or if that even matters. Anybody know the difference between 250 and 500 stock 2nd gear sizes?  :?

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