2008 Muffler Packing Issues

4 replies to this topic
  • MX926

Posted July 07, 2008 - 04:41 AM


-I just wondered if anyone else has had trouble with the packing in the 08 450.. Mine lasted about 3 weeks of hard riding, I repacked it, and had the same result.
-I then switched to a shortened 07 muffler, bike ran great, better performance, but same problem 3 weeks and no more packing left.
-I'm currently running a stock 07 muffler, and have no packing problems, however i would like to run the shortened 07 muffler becuase of the performance characteristics.
-I'm wondering if my jetting is affecting the exhaust temperature? My muffler is a nice gray color, and the bike seems to run great jetting wise. I mix 1 gal of power110 race fuel with 4 gallons of 93 octane. My jetting is:
168 main
45 pilot
clip in stock #3 position
Fuel screw 1-1/2 turns out
Bike is completely stock
I'm in minnesota where its been upper 70's and 80's.
And the packing I'm using is FMF 4-stroke packing, which I have used previously and had no trouble.
-Anyone have any suggestions?

  • mxracer206

Posted July 07, 2008 - 04:54 AM


If you can get 93 octane in your area then IMO you are wasting time and money on the race fuel. Your jetting should be OK. The 07 muffler is a much better exhaust but you may not be packing it well enough. If you are using the stringy style packing the only way I could ever get it packed tight enough is by taking off the end cap and packing it around the baffle. It is a little more work but will last longer. The best way is to buy a cartridge style packing like a lot of companies sell now but they are alittle more money.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • MX926

Posted July 07, 2008 - 05:18 AM


I've tried packing it super-tight, and I've have packed it in a normal manner. Both however seem to bring the same result. The packing I'm using is fmf 4- stroke which comes in non-string type. As far as the race gas, it seems to make everything a little crisper, and I'm getting a super good deal on it, otherwise I would just use pump gas.

  • grayracer513

Posted July 07, 2008 - 07:29 AM


168 seems rich for an '08, but the race fuel may be oxygenated enough to need that.

I have had poor luck using FMF packing in my son's DRD exhaust, and solved the problem by using the DRD packing cartridge. It is vastly easier to use (not to mention the reduction in loose glass fibers in/on your clothes), and has outlasted enough FMF repacks to have made up the difference in cost.

The '08 muffler is going to be hard on packing because the internal baffling forces a greater amount of exhaust gas into the packing.

  • Daltoneious

Posted July 07, 2008 - 05:38 PM


i had the stock pipe on my 07 for quite awhile and stock packing lasted about 30 hrs, and since i get no more then 10 to 15. i used fmf packing for awhile, but its garbage. i tried the moose cartridge style thats a little more money and bike specific and i got probably another 5 hours out of it, but it got to a point where re-riveting my pipe everytime was taking its toll. i've got a drd on there now and its about the same situation, every 10 to 15. how hard you're riding does affect it i think, but i guess just live with it, thats what i've come up with

Related Content


Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies

05 yz450f not fast enough by RedeyeYZ

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  38 replies

BIGBORE FOR YZ450F 2006? by Taattie94

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.