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Cracked Header???

By Raptor117,
in KX250F/X

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Raptor117

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Today I was cleaning my bike up and I noticed that I was able to wiggle the header. So I decided to unbolt it from the head and put it back on. Besides the header being able to wiggle a tiny bit, I had started my bike earlier and I noticed that it sounded like there was the sound of my exhaust coming from where the header attaches to the head. I didn't think anything of it and I just thought I was hearing things and it was only the engine running. Now that I had the header off, I noticed this crack. I am sorry for the picture quality, my camera sucks. You can see the crack though, it is what looks like a little scratch. It also runs along the top and it cracked right through the solder too.

100_1172.jpg?t=1236483751

The crack can also be seen on the inside(light shines through a little).

So now... First off, I am wondering if this is bad for my bike if I were to ride it like this. Second, I am wondering if it would be possible to fix it somehow until I am able to save up money for a new header. Third, can anyone explain to me how the hell this happened...

The only thing that I can think of is if the pipe was red hot, and it was cooled down way too fast. I doubt that it would crack from being hot and a rock hitting it.

My bike backfires like crazy too. I will give it a quick twist of the throttle and when I let off, BANG! The weather is pretty much back to normal now after the winter so I'm having trouble believing it is something with the jetting. So could the backfiring be caused by the crack, or is it just because my bike sat all winter and maybe the carb is clogged?

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Raptor117

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Well... I was able to get my uncle to weld the crack for a temporary solution. I won't have the pipe back for a few days though. I also figured that the reason it cracked was because it was hot and it probably occurred when I went through a cold puddle. So I basically answered my questions except for one, and I need you guys to help me on this.

Would the crack cause my bike to backfire? I won't be able to check of course like I already said, and I don't even know if my uncle will be able to weld the whole crack.

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Raptor117

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yes exhaust leaks are the main cause of backfire and decel pop, with lean pilot circuit being a close second ?

Thanks so much man! One more thing, got any good threads or sites that will show me how to set my idle? I've watched videos of like Ryan Villopoto on his 250f and it idles so much faster than mine.

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Luigic81

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Thanks so much man! One more thing, got any good threads or sites that will show me how to set my idle? I've watched videos of like Ryan Villopoto on his 250f and it idles so much faster than mine.

your supposed to use a "engine revolution tester" and set it to 2000 rpm's +/- 50r's but if you dont have one of those, then you can just set it by feel I suppose, just make it fast enough so that it does not stall in corners, and he throttle response feels good. A little trick I used to due to my gixxer was to turn the idle up way high so I was already "on the gas" when I let of the brakes, but that was roadracing, not so sure that you would want to do that here. Does your idle feel low, like it wants to stall in corners even with the clutch in?

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D-K

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Well... I was able to get my uncle to weld the crack for a temporary solution. I won't have the pipe back for a few days though. I also figured that the reason it cracked was because it was hot and it probably occurred when I went through a cold puddle. So I basically answered my questions except for one, and I need you guys to help me on this.

Would the crack cause my bike to backfire? I won't be able to check of course like I already said, and I don't even know if my uncle will be able to weld the whole crack.

I hope that you know that the stock header is made from titanium? It´s not stainless steel. Tell your uncle before he attempts to weld it. He will need to have a Ti rod when he welds it, most welders don´t have that...

If TIG welded with the wrong material it will just crack again, if it will even come together...

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joekikass

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I hope that you know that the stock header is made from titanium? It´s not stainless steel. Tell your uncle before he attempts to weld it. He will need to have a Ti rod when he welds it, most welders don´t have that...

If TIG welded with the wrong material it will just crack again, if it will even come together...

Very true and he needs to pre heat !

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Raptor117

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your supposed to use a "engine revolution tester" and set it to 2000 rpm's +/- 50r's but if you dont have one of those, then you can just set it by feel I suppose, just make it fast enough so that it does not stall in corners, and he throttle response feels good. A little trick I used to due to my gixxer was to turn the idle up way high so I was already "on the gas" when I let of the brakes, but that was roadracing, not so sure that you would want to do that here. Does your idle feel low, like it wants to stall in corners even with the clutch in?

Thanks man. It doesn't bog or anything, it is just that it doesn't idle fast like others that I hear.

Also, to you other guys, he will be able to weld it because he works in like a high tech shop kind of thing. I don't know what you want to call it, haha.

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Johnny_On_The_Spot

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Thanks man. It doesn't bog or anything, it is just that it doesn't idle fast like others that I hear.

Also, to you other guys, he will be able to weld it because he works in like a high tech shop kind of thing. I don't know what you want to call it, haha.

If there is no issue with the way the bike runs, i wouldn't worry about your idle.

The pro bikes have their idle set higher because of the aggressive cams they use. (More aggressive cam= less manifold vacuum)

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