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What's the deal with powerbmbs?

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I want to get rid of that stupid aluminum bushing that fits my powercore to my OEM header. It's a pain to get on or off, I'm pretty sure it leaks, and it looks like it was melting to the slip on and header...:lol:

I've got it off now and it is pretty screwed up so I'm not putting it back on, so that leaves me with either making another one because there's no way I'm paying $20 plus shipping for FMF to give me another one of these stupid things!

Or I could bend over and get one of their headers... But looking at their catalog they have an '01-'06 YZ/WR250F moto (040073) but their SX model is only '01-'03 (040122). I kind of want the SX model, but why don't they make it for the '04? Is there even a difference?

I'm kind of ticked I need to get a whole new header just to get rid of this stupid adapter sleeve:banghead:

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What? That's stupid!

Well anyway until I get the header sorted, I made myself a replacement adapter, but on mine I cut some 1mm wide by .5mm deep rings on the inside and outside of it to help it seal better. I also installed it with high temp anti-seize, and the fit to the header requited me to heat up the adapter a little and tap it on so it's a little improved and will hopefully work better. The fit to the slip on is a little looser because the welded seam on it prevents a precise fit. I'll probably need some high temp RTV on there, but I can't install the pipe assembly until I get a new ring for the header to engine seal.

I'm pretty sure this stupid little adapter was causing a slight air leak and giving me some jetting grief, but why is it there in the first place? i guess I might have to give FMF a call tomorrow and see what they have to say...

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Been runnng a Powerbomb with a Factory 4.1 for a couple of years on my 2006 WR250F with no issues. I first used the Factory 4.1 muffler and mid-pipe with the stock header. FMF supplied an aluminum sleeve to adapt the larger mid-pipe to the smaller header. The fit was good and they recommended a thin layer of high temp silicone in the joint. Worked fine with no detectable leaks. I then bought the Ti PowerBomb header and it fit to the Factory 4.1 very well. It eliminates the aluminum adapter. Again, it only required a thin layer of high temp silicone.

I can't believe that the aluminum sleeve can melt as stated by the original poster at the temperatures of the header and mid-pipe. You've got other issues that are not related to FMF.

I also just bought a Ti PowerCore 4 muffler and Ti PowerBomb header for my CRF450X. Same story...high quality and good fitment with the FMF products.

I don't understand the other comment either, that someone is having issues with the aluminum adapter, even though they are using a PowerBomb header. The Powerbomb header in my two cases eliminated the need for the aluminum adapter.

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I'm not talking about melting like dripping, it's just kind of "welding" onto the other part and it is all rough. The aluminum was actually sticking to the titanium and stainless of the other two parts. I got it off the header when I sandblasted it clean, but I had to scrape it off the slip on because I didn't want to blast that. The header can get hot enough to glow red, that's plenty enough to get the aluminum to stick to the other metals.

Using aluminum is a dumb idea anyway. First, it is yet another metal that expands at a different rate than the SS or Ti, and second mine was starting to anneal in quite a few places, especially around where it was sticking to the other pieces. I think that a SS piece would be much better suited to the task. It might even be worth the $20 they're asking for it:bonk: Another problem with the adapter design is that it makes twice the amount of places for a leak!

When I first installed it I used some High temp RTV, but it might not have cured long enough or something because it looked like most of it was gone when I pulled it off. I used it again when I re installed the exhaust with my new piece. I put the RTV on for the last half inch and high temp anti-sieze on the rest. Hopefully the combination of the grooves and the sealant on the last half will keep it from leaking.

One of the problems was that my header was slightly off round. It could be because the goon PO might have put the clamp-on muffler on to tight or maybe he had crashed it once (the heat shield was dented when I got it). That problem was mostly fixed when I put on my new adapter because it was such a tight fit, but it was still a hair off. It's also hard to get a good fit and seal on a piece of welded tube like the slip on, I guess that's why they recommend the silicone.

I might be willing to get a powerbomb if it means I'll be able to ditch the adapter, but I would want the SX version for the better low and mid power. Shouldn't the '03 work on later models? I would thing it would work but then why would they only have it listed for '01-'03?

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"I'm not talking about melting like dripping, it's just kind of "welding" onto the other part and it is all rough. The aluminum was actually sticking to the titanium and stainless of the other two parts."

Could it be more of a corrosion issue than a "melting" issue? Again, I don't think even a glowing red header is hot enough to melt aluminum.

"Using aluminum is a dumb idea anyway. First, it is yet another metal that expands at a different rate than the SS or Ti, and second mine was starting to anneal in quite a few places, especially around where it was sticking to the other pieces. I think that a SS piece would be much better suited to the task."

I haven't looked at the numbers. If the Ti alloy of the mid-pipe has a higher expansion than the SS alloy of the header, then you would want a material with an even higher expansion ratio, like alum to compensate for the temp change. Again, I haven't looked at the numbers.

"When I first installed it I used some High temp RTV, but it might not have cured long enough or something because it looked like most of it was gone when I pulled it off. I used it again when I re installed the exhaust with my new piece. I put the RTV on for the last half inch and high temp anti-sieze on the rest. Hopefully the combination of the grooves and the sealant on the last half will keep it from leaking."

The RTV won't last forever and, if the fit is good, it will be a very small gap with a very small amount of RTV. If it adhered well, some should stick to both sides when you pull it apart, so it can appear as though the gap was filled incompletely. I always clean the surfaces very well with isopropal alcohol before applying the adhesive. I'm not sure how well the chemical interaction of anti-sieze material with silicone adhesive in the same gap will work.

"One of the problems was that my header was slightly off round. It could be because the goon PO might have put the clamp-on muffler on to tight or maybe he had crashed it once (the heat shield was dented when I got it). That problem was mostly fixed when I put on my new adapter because it was such a tight fit, but it was still a hair off. It's also hard to get a good fit and seal on a piece of welded tube like the slip on, I guess that's why they recommend the silicone."

It could be that poor fit was due to PO bending header and that provided path for moisture to cause excessive corrosion?

"I might be willing to get a powerbomb if it means I'll be able to ditch the adapter, but I would want the SX version for the better low and mid power. Shouldn't the '03 work on later models? I would thing it would work but then why would they only have it listed for '01-'03?"

Not sure. I thought the same things when I bought mine. Sounds like you're on the right track, though. Keep working at it!

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"I'm not talking about melting like dripping, it's just kind of "welding" onto the other part and it is all rough. The aluminum was actually sticking to the titanium and stainless of the other two parts."

Could it be more of a corrosion issue than a "melting" issue? Again, I don't think even a glowing red header is hot enough to melt aluminum.

"Using aluminum is a dumb idea anyway. First, it is yet another metal that expands at a different rate than the SS or Ti, and second mine was starting to anneal in quite a few places, especially around where it was sticking to the other pieces. I think that a SS piece would be much better suited to the task."

I haven't looked at the numbers. If the Ti alloy of the mid-pipe has a higher expansion than the SS alloy of the header, then you would want a material with an even higher expansion ratio, like alum to compensate for the temp change. Again, I haven't looked at the numbers.

"When I first installed it I used some High temp RTV, but it might not have cured long enough or something because it looked like most of it was gone when I pulled it off. I used it again when I re installed the exhaust with my new piece. I put the RTV on for the last half inch and high temp anti-sieze on the rest. Hopefully the combination of the grooves and the sealant on the last half will keep it from leaking."

The RTV won't last forever and, if the fit is good, it will be a very small gap with a very small amount of RTV. If it adhered well, some should stick to both sides when you pull it apart, so it can appear as though the gap was filled incompletely. I always clean the surfaces very well with isopropal alcohol before applying the adhesive. I'm not sure how well the chemical interaction of anti-sieze material with silicone adhesive in the same gap will work.

"One of the problems was that my header was slightly off round. It could be because the goon PO might have put the clamp-on muffler on to tight or maybe he had crashed it once (the heat shield was dented when I got it). That problem was mostly fixed when I put on my new adapter because it was such a tight fit, but it was still a hair off. It's also hard to get a good fit and seal on a piece of welded tube like the slip on, I guess that's why they recommend the silicone."

It could be that poor fit was due to PO bending header and that provided path for moisture to cause excessive corrosion?

"I might be willing to get a powerbomb if it means I'll be able to ditch the adapter, but I would want the SX version for the better low and mid power. Shouldn't the '03 work on later models? I would thing it would work but then why would they only have it listed for '01-'03?"

Not sure. I thought the same things when I bought mine. Sounds like you're on the right track, though. Keep working at it!

The aluminum adapter piece for my SS powerbomb and SS Q4 has also become rough and appears to be corroding. The male end of the adapter has literally gotten thinner. All of the components were new when they went on the bike and I even used FMF sealant.

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OK, I asked the boss about it and he said it was heat fretting. Basically the aluminum gets not quite hot enough to melt outright, but the vibration kind of helps it along. So you were right about it not melting. Here is a picture of the best example of it on the part:

20111201172304893.jpg

You can also see the scratches in it from where the aluminum had fused to the Ti header on the other end of the part and gouged it as I pulled it off.

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I'm not familiar with the term "heat fretting" but "galling" comes to mind when looking at the pic.

From Wiki:

Galling or adhesive wear is often found between metallic surfaces where direct contact and relative motion have occurred. Sheet metal forming, thread manufacturing and other industrial operations may include made parts of stainless steel, aluminium and titanium[2] that are particularly susceptible to galling.

In metalworking that involves cutting (primarily turning and milling), galling is often used to describe a wear phenomenon which occurs when cutting soft metal. The work material is transferred to the cutter and develops a "lump". The developed lump changes the contact behavior between the two surfaces, which usually increases adhesion and resistance to further advancement and, due to created vibrations, can be heard as a distinct sound. An example of a change in material behavior can be seen in figure 4.

Galling often occurs with aluminium compounds and is a common cause of tool breakdown. Aluminium is a ductile metal, which means it possesses the ability for plastic flow with relative ease, which presupposes a relatively consistent and large plastic zone. In comparison, brittle fractures exhibit a momentary and unstable plastic zone around the cutter, which gives a discontinuous fracture mechanism that deters the accumulation of heat.

High ductility and flowing material can be considered a general prerequisite for excessive material transfer and galling build-up because frictional heating is closely linked to the constitution (physique) of plastic zones around penetrating objects and, as mentioned, brittle fractures seldom generate a great amount of heat.

Galling can occur even at relatively low loads and velocities because it is the real local pressure or energy density in the system that induces a phase transition, which often leads to an increase in material transfer and higher friction.

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Yes, I'm pretty familiar with galling. This is apparently very similar but different. Usually when I have parts gall up it's something like a close tolerance thread where both parts are aluminum and not lubricated. You screw them together without any lubrication and they lock up. Then you're... screwed... This looks like it's pretty similar, but instead of material snowballing due to abrasion, it is heated and then the vibration causes it to ball up. I've never had two dissimilar metals gall up before either, but I might just be lucky in that department...

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