Two Stroke Motocross
Two Stroke Motocross Forum => Technical => Topic started by: KXPegger on September 07, 2013, 10:11:08 PM
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Todays ride report after installing the Platinum II on my 2012 KTM 250SX.
Did not start out well. It fired a few times and then partially fouled a plug. Loaded the bike up and took it to the nearest steep hill to bump start it. Bike fired up and ran okay but just slightly goofy just off idle like it was trying to foul a plug for just a second and felt like maybe a little rich. After the bike warmed up a little she was her old self again and ran fine!
Definite bottom end and mid-range improvement with nothing lost on top. The pipe is great!
After the trip home with the bike nice and cold I turned the idle up one turn and the air screw out 1/4 turn. The bike started first kick and all the previously mentioned problems gone. The bike runs great! Very happy with the Platinum II.
Later!
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I ran the FMF fatty to replace my OEM pipe after a bad catapult off the face of a jump cracked it in two seperate places and therefore severely weakened its structure. Next practise day I washed out on some really slick terrain and slid for a meter to find my pipe wrapped around the frame. so it was time for a new one
My biggest concern is how far it hangs below the frame no less than two inches and probably more. I don't remember my oem pipe being that low. More comprehensive review to come.
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PC II maybe an inch below the front part of the rails and even with the rear section. I'm using an E-line guard so I'm not to concerned about it. I do the think the OEM sat a little higher and didn't hang as much below the frames rails but with the pipe cracking all the time I guess it didn't matter where it hung. KTM does a lot of stuff right but two stroke pipes isn't one of them!
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PC II maybe an inch below the front part of the rails and even with the rear section. I'm using an E-line guard so I'm not to concerned about it. I do the think the OEM sat a little higher and didn't hang as much below the frames rails but with the pipe cracking all the time I guess it didn't matter where it hung. KTM does a lot of stuff right but two stroke pipes isn't one of them! 
According to my local track president/mechanic/ex national pilot/tyre changer/mate, the pipe itself its of solid and good construction and its issues are a result of motor vibrations.
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Sounds like a good theory to me! Maybe all KTM needs to do is find the critical speed frequency that is causing the resonance (self-excitation) and change the pipe design a little so it doesn't or won't vibrate itself apart. Maybe something as simple as some rubber tubing over the springs may be enough to dampen or change the destructive frequency enough? I'm trying to sound smarter than I really am!
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Sounds like a good theory to me! Maybe all KTM needs to do is find the critical speed frequency that is causing the resonance (self-excitation) and change the pipe design a little so it doesn't or won't vibrate itself apart. Maybe something as simple as some rubber tubing over the springs may be enough to dampen or change the destructive frequency enough? I'm trying to sound smarter than I really am! 
Well hes had some EXC pipes brought in that actually cracked on the inside, and the exhaust port scavenging dragging the debris back in to the motor
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Sounds like a good theory to me! Maybe all KTM needs to do is find the critical speed frequency that is causing the resonance (self-excitation) and change the pipe design a little so it doesn't or won't vibrate itself apart. Maybe something as simple as some rubber tubing over the springs may be enough to dampen or change the destructive frequency enough? I'm trying to sound smarter than I really am! 
Well hes had some EXC pipes brought in that actually cracked on the inside, and the exhaust port scavenging dragging the debris back in to the motor 
Thought about doing another ride with my cracked pipe. Glad I didn't!
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I had my 2012 250sx for 5 months before the pipe cracked. I got it welded then a month later I got another crack in different place. So I got that welded then a couple of weeks later the weld cracked on my first repair so I said screw it and got a fmf fatty. On a related note, my fmf titanium 2 silencer rattled itself apart after 8 months but fmf replaced under warranty. It seems like ktm makes the good silencer and fmf makes the good pipe lol