exhaust pipes dented

[lele]

Hi,

I found a dent on the exhaust pipe in one tube.On Internet I search for the best method to repair it and everyone said to remove the entire pipes, put plugs and blow it with compressed air while heating up the dented area with a torch.Now my big question is: instead of removing the pipes, can I leave them on and use the engine exhaust pressure while heating up with the torch? is this pressure sufficient to blow it? AND...using a torch can damage the pipes?

thanks

 

[Donal]

How bad is the dent?

Can you post pictures?

If it is not seriously restricting exhaust flow I would leave it alone......... YMMV

 

[lele]

is a flat medium size dent..

I don't think it compromise anything

but if it possible an easy repair...why not?

don't know how to upload pictures on this forum yet

 

[Donal]

I don't believe it will be possible to use exhaust pressure to remove the dent.

To achieve any back pressure you will have to block both exhausts (common header), the engine will not run............

 

[eflyguy]

Air pressure is not going to work, especially not exhaust from the engine.

Unless it's major, leave it alone. If it is major, perhaps someone has a set of headers from a part-out.

 

[MrZappo]

Exhaust pressure and a blow torch? That sounds a little drastic to me. You might end up with an undented pipe and a blown engine.

I'd live with it or buy a new pipe.

 

[lele]

Air pressure is not going to work, especially not exhaust from the engine.
Unless it's major, leave it alone. If it is major, perhaps someone has a set of headers from a part-out.

I found a lot of videos on youtube where people use pressure and heat to restore dented headers

(specially motocross bikes headers)

 

[redzgrider]

Back in the day, Hooker headers were fairly famous for having a 'hammer' fit -- they often need a dimple here or there just to get them into the car. We're talking something like a 1" flat spot or similar? Perhaps from a jack lifting the front wheel by the pipes? If you're not running around at near red line, there is no way on earth it's worth your time to fix that.

 

[hppants]

The biggest concern is if the dent restricts the exhaust enough, that cylinder will run hot because the hot exhaust gasses cannot escape the motor. If it runs hot enough and over time, it could cause engine damage (burnt valve, spin a crank bearing, or worse). We think that Patriot's grenade Gen 1 motor may have been caused by this issue.

Does anyone know if the header for the FJR is single walled or double walled?

I've seen success in repairing a dent only on a single wall Mac motorcycle header. We used a large chest type freezer. It took a few tries adding a little more water until we had just enough to expand the dent out when the water froze. We used rubber plugs and hose clamps on all of the holes to hold the water.

I do not think this would work on a double wall header.

 

[Ignacio]

It took a few tries adding a little more water until we had just enough to expand the dent out when the water froze. We used rubber plugs and hose clamps on all of the holes to hold the water.

Did that header have catalytic converters in it like the FJR? I'd have pause about freezing water in those meshed honeycombs residing in our particular headers.

Does anyone know if the header for the FJR is single walled or double walled?

Single walled...at least in the area that is commonly dented.

And back to the original OP's addition:

is a flat medium size dent..I don't think it compromise anything

I wouldn't bother unless you're a stickler for performance and/or rodding it near red line all the time.

 

[hppants]

No cat converter. It was an old Mac 4-1 header. We removed the baffle and cone and plugged the five holes.

To the OP - if u have or have access to an infared thermometer, take some temperature readings on all four holes at the head exhaust once the bike is at running temp. If no appreciable difference between the dented hole and the others, I'd say leave it alone.

 

[lele]

thank u all.

my next winter project is remove the headers and try with compressed air + torch..(maybe put some photos)

I just been in souther France and the bike run great! (also with the dent..)

 

[WBill]

I dented one of mine about 20,000 miles ago, cutting a right hand turn a little too close by a parking lot curb. You have to look close to see it, but I know it's there. I haven't noticed anything different in the way the engine performs. WBill

 

[SacramentoMike]

I hit a good sized rock some years and two FJRs back, ruined the front wheel and left a significant dent in two of the header pipes just above the curve. Made NO difference in how the bike ran. Only bothers you if you are--no offense intended--just anal about perfection. I am not, at least for aesthetics (in fact, I don't look perfect myself). I'm with the "leave it alone" folks.

 

[lele]

Yes I'm too much for perfection.

because I'm Italian..

anyway Mike I'm not interested in aesthetic but mechanically my bike must be perfect.