Very Quiet Power Core II

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jc7622
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Very Quiet Power Core II

Post by jc7622 »

I recently bought an FMF Power Core II off of Ebay. None of the riding areas around here require a spark arrestor. I polished it all up and got it looking good and re-packed it. This weekend I tried it out.

Believe it or not it was about the same as my stock silencer in terms of noise level. I didn't expect this. I expected it to be louder but it wasn't. What gives? Almost every other post I have read said that it would be noticeably louder. I don't know if it makes a difference, but I don't pack my silencer real tight like the instructions say to do. Home insulation, sleeping bags, etc all work best when the insulation is allowed to loft properly so I wrap my silencers using the same logic. Maybe that had something to do with it????

The silencer did help the throttle response just slightly - not much but enough that I could tell a difference when I blipped the throttle.
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Post by Ondatrail »

Do you have an aftermarket stinger? That would make the most difference.
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Post by jc7622 »

Nope. Just the silencer. It was no louder than the stock unit. Of course I assume it will slowly get louder and louder until it is repacked again.
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Post by treelimb »

hey jc7622- back some time ago I emailed jeff fredette about packing the silencer on my 1987 KDX200 and he stated to pack it as tight as possible.Therefore i apply the same advice to both that bike and my 1997 KDX200. Just an FYI which may get a bunch of replies to the contrary but Jeff Fredette did indeed advise me to do just that.
You probably just have not noticed the large amount of difference yet.you will as soon as you ride the bike all day,everywhere you can,up and down and in and out of every possible scenario imaginable.
enjoy it.
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Post by jc7622 »

Maybe someone shold do a test on packing tightly and loosely - both for noise absorption and service life of the packing. It seems, and I could be all wrong, that it is theoritically possible to wrap packing so tight that it has virtually no sound absorbing ability.
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Post by jc7622 »

I just read on another board (the orange one) that packing loosely can really help to quiet a bike down. This was posted by the owner of some high performance mini shop in AZ.
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Post by canyncarvr »

Re: 'Believe it or not it was about the same as my stock silencer in terms of noise level.'

That's a measured level? If it's not, if there is no quantification, the pressure level of either is still unknown.

Re: 'all work best when the insulation is allowed to loft properly so I wrap my silencers using the same logic'

What db is that loose sleeping bag good to? :hmm:

Maybe this is a matter of imos from hither to yon...but the general rule of thumb is to pack tight. I've tried both..looser packs were louder (using the non-definitive 'seems to me' method) and lacked the performance of tighter packs. Was the tighter as tight as I could get it? No.

The Azirona shop guy is wrong. Maybe that's why his shop is mini.
Curious...what SPL testing device did he use?

A btw...but I would figure it impossble to pack packing tight enough so as to NOT absorb sound. As long as we're mixing metaphors here (a figure of speech..regarding db and º), that would be akin to pouring a glass of water SO BIG... the water wasn't wet anymore.

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Post by GS »

Carvr....."a glass of water SO BIG... the water wasn't wet anymore"

You've gone to the next level with that one!!! :lol:
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Post by jc7622 »

canyncarvr wrote: Maybe that's why his shop is mini.
Have you ever been around any mini racing (50's, 65's, 85's) either locally or at some place like Ponca City or Loretta Lynns? They take it pretty seriously (kids as well as dads). In the classes it is allowed in, they get pretty extreme with the level of mods. I wouldn't say that because someone specializes in minis it means they don't know anything about bikes.
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Post by canyncarvr »

It was a JOKE!

Yanno...'mini' as in SKIRT? ..small?

As in Inda's avatar?

A hint was the word being used as an adjective.........

:wink:

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Post by jc7622 »

I'm sorry. I am very sensitive about the word MINI right now. Every time I hear the word MINI it reminds me about how much these little minis are costing me. They are not as reliable as a KDX and need constant upkeep. Now all three of my youngsters want to start racing. I gave that up years ago because it cost too much. Now I am looking at maintaining three of these little high RPM screamers.
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