powerbomb header

[400exJOE]

Does an FMF Power Bomb header make a big difference on a 400ex that already has an aftermarket silencer? I have a Supertrapp IDS2.

[knighttime]

I noticed a big difference.

[kabd69667]

In the new dirtwheels they did a dyno on the powerbomb and the power core IV Q and it gave you like 1.7 horsepower more.

[out4sand]

It helped a lot with ours, we have a FMF Power bomb & Mega Max II. If you do install one make sure you check your jets because we had a to jump up a few. The only draw back that I have found is that they don't seal real well and I seem to always have an exhaust leak at the joint where they connect together. But over all it was a big improvement over stock.

Just make sure the O-ring is in the muffler when you put the header pipe on ,,,it will fall out easely and cause problems,,I haven't had any problems with mine...

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[out4sand]

Yeah. I have had problems with the o-ring...mine has never fallen out it actually end up sort of melting and then warring out due to the vibration I guess so I have a constant exhaust leak at the joint. That is the only thing I don't like about the pipe but most seem to connect in that fashion so I guess that is just it gos.

[400exRacerX]

Weres this O-ring at? And its not to good at all to be riding around with a exhuast leak, that leaks to exhuast valve dammage.

[out4sand]

The o-ring is just inside the silencer (Mega Max) where the head pipe slides into. It's roughly an 1" inside I would say. There is a cut out area/ring inside the silencer where the o-ring sits. When the O-ring is first installed it works all right but once the bike is ridden it just starts to fail. I have tried a couple different things like adding some high temp gasket sealer when I put a o-ring in but that just melts/blows out over time and I also bought this clamp off ebay that worked for a bit until we went on a super long ride at St. Anthony's and then the hose material started to melt. I also tried to secure the silencer better by adding some fender type washers to help hold the rubber mounting deals better but the silence just never sits "perfectly" tight so when you ride it hard it vibrates making the o-ring fail over time (a pretty short time actually). Any ideas on a fix? :confused:

I don't think mines ever given me a problem,,I guess I could check it.

[out4sand]

Yeah, do that and see if leaks at all (if you don't mind), I sure would like to know if I am the only one that has this problem. It doesn't leaks all that bad but it does a little. I also purchase the first run of Mega Max's that FMF made for the 400ex so maybe they have changed the way that they mount or how the o-ring sits on the newer models.