Making exhaust quiet

I have a power core 4 on my 99 yz400f. Its loud as hell. What can I do to make it quieter?

I would love a stock one, but I doubt anyone will see my for sale/trade thread since they are not included when you hit the new posts button

Does it need repacking?

I had a Powercore 4 and recently went to a Q4 on my 03 450. I found the power core to be embarassingly loud; even after repacking it. Now I'm trying to figure out all those sounds from my motor I never heard before....... It's probably not as quiet as stock, but well below and acceptable db. I dont notice any difference (loss) in power.

The bike has plenty of power, I am not worried about losing any, maybe I should take the end cap off and take a look.

Is there anything I can do besides repacking that wont create too much back pressure? (I was thinking welding some holes shut, from what I can imagine there are discs with holes in them to allow exhaust to pass by?)

FMF Makes quiet inserts for these. $27 on their website. It is supposed to make it legal. Im sure you will notice a tiny power loss, but who can ride their bikes to their max potential besides pros? Worth not getting a sound ticket

FMF Makes quiet inserts for these. $27 on their website. It is supposed to make it legal. Im sure you will notice a tiny power loss, but who can ride their bikes to their max potential besides pros? Worth not getting a sound ticket

+++rep!

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picture from ebay, this looks like it can be easily made...

48fc_2.JPG

picture from ebay, this looks like it can be easily made...

yeah, buy one from a local shop, take measurements and take it back. Then make one.

I couldn't do that, Ill take the exhaust apart and see what I can do. or just spend the 35 bucks...

tried it. the improvements are marginal at best.

hmm, thanks... i really need to find a stock one. Do all yz4XXf's fit? 250f's? any 2 smokers?

Anyone?

No. The only stock ones that will bolt up dependably are those from a 400/426. The '03-'05 comes close, but not quite. Later ones, not even.

The stock ones aren't that quiet, frankly.

They are always on e-bay for pretty cheap. I think that 1998 - 2002 400/426 are all the same. I had the same problem and went to a stock pipe with the pro moto billet end cap with spark arrester and quiet insert when I need it. Even without the insert it is not too loud and runs way better than with the e-series.

Sorry for hijacking the thread, but have some questions on repacking. Last year I've broke my silencer, friend pulled a wheelie, but hes gone all the way to 360 :lol: so the end of the pipe got stuck in the ground and bended it, so I've pulled it apart, straightened it and put back what was left of the packing. Never saw one new but this looked like hell, all black and like rasta hair :worthy:, in big chunks. Should I repack it? Will it be quieter? Does it have any gain/reducement on performance?

thx

Freshly packed mufflers are quieter and perform better.

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