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2009 KTM 65 SX restrictor

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I have seen restrictors advertised that fit in the exhaust at the cylinder...

I can turn one of these myself however I am not certain what size the hole in the middle should be. Ideas??

Also, can this damage the bike at all??

Thanks!

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I made a restrictor for my son's KX65. I used a washer with a 1/2" hole and it worked great. Just as the bike would start coming on the pipe the power would go flat. Once he was used to that I drilled it out to 7/8" and left it there till he got used to the way it felt when it was coming on the pipe. By the time I removed it he was used to the way the power came on and it didn't scare him for more then the first 20 minutes - then he had a huge smile on his face.

The nice thing was it required no rejetting and never fouled a plug. I recently put a new top and bottom end in the bike and was happy to see that there was no damage whatsoever to the top end.

The thirty dollar question: Could he have learned without the restrictor? Yes. But I think he learned faster with it. He wasn't intimidated by power of the bike while learning how to use the clutch, rear brake, etc. :)

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Thanks for the info. I've read several post on this but you are the first I've seen that actually posted the size of the hole. I agree, learing to use a clutch is imtimidating enough without worrying about a powerband also. We can't all afford to buy a CRF80 just to learn how to use a clutch and then buy a 65cc MX bike a month later.

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I have seen restrictors advertised that fit in the exhaust at the cylinder...

I can turn one of these myself however I am not certain what size the hole in the middle should be. Ideas??

Also, can this damage the bike at all??

Thanks!

Whoa, if it's a '09 65sx (equipped with a powervalve), I wouldn't mess with it without consulting your dealer. New design, the Austrians are still working out the bugs on the bike. I wouldn't touch anything on the exhaust side.

Now you may want to ask the dealer about installing a washer on the intake side - between the carb and the reeds. Polini did this on the X3's so that new riders could get used to the bike, once they wanted more power, you take the washer out and it lets the engine breathe as intended.

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From what I've seen that 09' has torque like an electric bike. It should be super easy for a kid to learn the clutch on. My buddy says it pulled him from almost an idle and didn't stall he's 160 or so. Also isn't there a line from pipe to powervalve, I'm sure velocity acuates the valve if you restrict the flow it may affect this.

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Now you may want to ask the dealer about installing a washer on the intake side - between the carb and the reeds. Polini did this on the X3's so that new riders could get used to the bike, once they wanted more power, you take the washer out and it lets the engine breathe as intended.

A friend of mine just bought a KX65 for his son and is woried about the power as well for his son at first while learning. Would you have to worry about jetting when putting a washer in the intake like you desribed here? Or should he not worry about it?

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A friend of mine just bought a KX65 for his son and is woried about the power as well for his son at first while learning. Would you have to worry about jetting when putting a washer in the intake like you desribed here? Or should he not worry about it?

I don't know if the KX's are jetted lean or rich out of the box - I'd ask one of the tech's at the local dealer, explaining the goal and the concept of restricting intake, get their recommendations. I know that with our son's Polini, we went down on the main and up on the pilot, but that was due more to altitude than anything else. Heck, they may know of a better way that works as well, if not better.

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Jr drove the bike a few days bike for the first time this year and had zero problems on it....After one lap it looked natural for him. I will leave it be but thanks to all who posted comments here...

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