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I planned on removing my carb today and giving it a good cleaning. When attempting to remove my header (to access the carb), I noticed it was very hard to do so. The header flange is bent. After working it a bit, I finally got it off. It also looks like the lower header bolt is bent slightly downward.


I have absolutely no idea how this happened. I just assembled the motor (new piston, rings, valves, etc.) two weeks ago and have only ridden it once. There is no sign of anything having hit the header, the flange, or the bolt/nut. I didn't go down, and that bolt/area is directly behind the frame--there is almost no way anything hit it.

Questions:

Has anyone seen this before? How could this have gotten bent? This is a MRD low/mid R header and flange.

Should I attempt flatten the flange or will it be too weak?

Can the lower header bolt be removed from the head, if not, is there a safe say to bent it slightly (like 1mm) upward?

Thanks all.

The 2 "bolts" that hold the header to the head are just studs. The run about $2 each and are replaceable. Hardest (scariest?) part is getting them to come out. In most cases once you start your are married to it, and sometimes the marriage is not pretty, other times they just come right out.

Not sure what to say about the flange. I have no experience with the 450X exhaust, but if it was on my sons 250 I would just straighten it out. The only thing it is doing is helping the header compress a copper ring. Torque specs are really low, so I doubt it will bend again from putting it back on. Just be sure to not let the header support your muffler, ever.

riddler9 wrote:The 2 "bolts" that hold the header to the head are just studs. The run about $2 each and are replaceable. Hardest (scariest?) part is getting them to come out. In most cases once you start your are married to it, and sometimes the marriage is not pretty, other times they just come right out.

Not sure what to say about the flange. I have no experience with the 450X exhaust, but if it was on my sons 250 I would just straighten it out. The only thing it is doing is helping the header compress a copper ring. Torque specs are really low, so I doubt it will bend again from putting it back on. Just be sure to not let the header support your muffler, ever.

Thank you.

I heard back from Dave at MRD almost immediately. Only logical explanation is that I over tightened.

Luckily, the studs came out very easily, and I was able to straighten the flange in a vice following Dave's instructions.