Header dent: need advice

Hi all;

Running a 1999 wr400 with all the popular mods done by the PO.

The problem: Header has a couple dents in it, looks like it's been dropped on a rock. Dent 1 is roughly the size of a dime, about 1/4 inch deep, and Dent 2 is roughly the size of a quarter, 3/8 inch deep. Is this going to wreak some havoc on my power? Create hotspots on the pipe? Possibly dmg anything? Is it worth paying the 250 bucks for a new aftermarket powerbomb header?

Also, was thinking about repacking the muffler to make the noise levels a little more rider-friendly, as 2 hours on the bike gets hard on the hearing... I'm not entirely sure there is any packing in the current muffler. Will I need to re-jet?

Any insight would be appreciated... first time 4 stroke owner, first time 4 stroke maintainer.

Edited by ArcticWR400
Spelling is hard >.<

Fill the area of the dent with water ... cork both ends and put it in the freezer. As the water expands it will push the dent out. You may have to repeat a couple of times but it works!

Check E-Bay for a used stock one. I bought one a while back there.

Fill the area of the dent with water ... cork both ends and put it in the freezer. As the water expands it will push the dent out. You may have to repeat a couple of times but it works!

Seriously? Never thought of that... it's GENIUS :banana: Thanks!!!

I can second that, in the 1970 I used to put my two stroke pipe in the freezer in the garage. Mom didnt care for it but it does work

Seriously? Never thought of that... it's GENIUS :thumbsup: Thanks!!!

It sure does. Do a search. Many others have used this method.

I took a golf ball sized dent out of a WR450 pipe with the freezer method. By the time I finished working the dent out of the heat shield with some body hammers and some sanding you'd hardly tell it got mashed. I believe the thicker stainless pipe from the YFZ450 quad would work on your bike. I know it works for the earlier 450's

Steve

Ok, so my header is in the freezer as we speak, I should have taken some "before" pics to show you all, but seeing as I failed that, I will just let you know how it turns out.

Thanks for the advice and pointers!:thumbsup:

You shouldn't have to re-jet when you re-pack the muffler. It will run better, tho...

It worked like a charm! The two main dents are completly gone. The only evidence is some dirt / corrosion that was sitting in the dent!! I will be getting full flow through the pipe now, looking forward to seeing if it changed the way it rides at all, even if minorly.

Packing, new handlebars (renthals) and a chain slide (swingarm protector) are on their way from the TT store... and my local dealership has my new grips in already. Can't wait to get this baby geared up for summer! New chain and sprockets next month, and perhaps a new headlight and I'll be getting hot under the collar waiting for spring... or I'll just tough it out and use the studded tires and ignore the cold! WOOT!!!

It worked like a charm!
:thumbsup:

It didn't work on a PowerBomb header :thumbsup: or very little. 15+ cycles.

from what i've since read, it won't because of that larger section and the stresses of teh metal. Also won't work on 2 stroke expansion chambers, which is kinda what a power bomb header is like, a small f'd up expansion chamber that looks like your exhaust pipe has a tumor. works just on the 4 stroke pipes that are more or less the same size from head to mid pipe i think...

I think it depends on the thickness of the metal. Doesn't it?

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