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kx65 piston life need some help

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so to start things off i normally ride a kx125 and im 15, 5' 10'', and 133lbs. i have a ttr110 play bike that i beat to sh!t over ramps jumps and what ever with. so my dad got me a slightly used 2001 kx65 to play around on since i like 2 smokes better. the top end it came with is fresh and compression is great. all stock. so far i put about 3 hours of straight beating on it. suspension has turned to soup and rear tire has lost a good amount of tread. my riding style is similar to what i do on my ttr110. jumping it, riding it hard, and i mean HARD, bottoming out the suspension, and occasionally hitting the rev limiter. right now, the bike idles a little bit higher than it did and i can tell im starting to lose some power, and its about a half hour away from needing a new piston/rings/ect. so what can i do to increase the top end life of this little rocket, and no, riding softer is not the answer im looking for

please help

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What oil ratio are you runnning? If you are riding that little thing that hard, I'd use 20:1.

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i use 32 1 mixed wit klotz full synthetic racing oil and 93 octaine high test. and okay, ill try 25:1 first tho

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At your weight there's more strain/heat on the motor, which creates a leaner condition, much like riding in the sand. Going up a size or two on the main jet is probably going to be needed. You may well discover that getting the jetting correct at full operating temps means it's a bit rich until then.

If you really like the KX65, you may want to find a kid with a 02+ bike that's too tall for them and trade them. The 00/01 KX65's were shorter than the 02+ bikes.

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At your weight there's more strain/heat on the motor, which creates a leaner condition, much like riding in the sand. Going up a size or two on the main jet is probably going to be needed. You may well discover that getting the jetting correct at full operating temps means it's a bit rich until then.

If you really like the KX65, you may want to find a kid with a 02+ bike that's too tall for them and trade them. The 00/01 KX65's were shorter than the 02+ bikes.

really? how much shorter? and i heard something about the engines are different. do you know what that would be? good idea about the jetting. im gunna get a size up and run 25:1. also i will be adding 2 teeth to the front sprocket since i top out way to early, like 40+ mph. so im going for 50+

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Increase main size, re-spring the bike. It is set up for a 60 pound rider.

The KLX110 makes about 7 hp the KX65 makes 18 hp. Higher state of tune, less life. Thhere is no way it is going to live long with what you are doing. It is a track bike. That bike is made to do 20 minute motos, not be flogged for 3 hours by a guy 3 times the designed weight. Ever wonder why the never did 2 stroke play bikes? That is why.

Run 28:1, up the main, re-spring the bike, re-ring it as needed, make sure it is not over heating.

Good luck!

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thanks for the response. but how can it possibly over heat? its liquid cooled. and where can i pick up some stiffer springs? bbr doesnt make anything good except for handle bars

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thanks for the response. but how can it possibly over heat? its liquid cooled.
Ahhhhh yesssss, well... that explains a lot about your situation actually.

For springs and what not check here. http://www.mx-tech.com/

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you can still overheat liquid cooled bikes.

You can get new dog bones and raise the bike's height.

You'll need to get it resprung - stronger OEM springs are available but likely NOT in the rate your weight requires.

It's definitely not made for your riding style so keep money aside for fixing it, actually - with your weight and how you ride, I wouldn't be surprised if the crank will drop and you do a bunch of tranny damage to it as well - they're just not made for that weight continuously beating on it.

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Go easy on him. He's 15. I was just starting to pull bikes apart back then. Anyways back on topic.

The bike would never overheat if it had a thermostaticly controlled fan. If you just sit there it will eventually build up. If you really flog the nards off it stick it in a high gear just out of the power band and let it cool down a bit before stopping.

As to your question. IMHO changing out piston and rings is cheap and easy when compared with replating the cylinder. I paid $250cdn to get a 01KX65 plated. If you are noticing a lack of power stop right now and tear it down.

BTW why would you want to ride a bike that is to small for you when you have the other motocrosser available.

My friends son is racing some CMRC and is starting to do doubles. He is 9 and wheighs all of 65lbs. I bought him an Ohlins shock for christmas. Although it is great it completely brings the problem with the stock forks into view. He is bottoming so hard his wrists hurt. At your weight you would be breaking wrists if you were riding that hard.

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ha yeah my wrists get pretty sore at the end of the day, and idk, its just alotta fun ripping around on a little 2 stroke

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Oh yes for sure, it is huge fun! Definitly and stiffer springs and revalve. Remember though, you got to pay to play. Post the resulllts of you get the big bore kit!

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yeah so for now im setting the "in need of new top end" kx65 aside and im going to save for the bbk, 28mm carb, and a 2 teeth up counter sprocket. ill definatly have the stuff by october. ill post a rev vid and a flyby vid. (i have a camcorder)

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The 02+ bikes are about 2" taller than the 00/01 bikes. Additionally, the frames on the early models were prone to cracking under hard use.

Getting the suspension right will make it much more fun to ride than adding any extra power. Finding an aftermarket triple clamp with forward mounted bar mounts would also increase the comfort. Completely swapping the fork assembly for one off a 85 or a KTM65 might be your best bet, as the stock forks are rather thin and can bend under hard use.

Making the piston bigger will just exacerbate any potential overheating issues. More power, combined with thinner cylinder walls will create more heat. It will also put more load on everything else, from the crank (a bit of a weak spot on those motors) to the trans, and on down the line. Given the fact that you're alredy stressing the bike due to your weight, you may want to spend your money elsewhere. But it is your money.

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