Exhaust repacking questions YZ426F

7 replies to this topic
  • Ztard

Posted August 13, 2007 - 05:03 PM


Yes I searched..without success.................

Ok I have a 2002 YZ426F with a stock pipe, and a pro moto billet end cap/spark arrester that I run supermoto events with. 4 trackdays ago I was performing some regular maint,oil chang etc.... I noticed that the front of my muffler was loose and the rivets were also loose. I decided since I had never repacked the pipe might as well do it while I'm here.

OK took everything apart and found a mesh screen with what looked like steel wool under it and around the pipe core, also the normal fiber tpye packing material around the outside of the mesh screen. all of the outer material was pushed to the back 1/3rd of the pipe. I discarded all of this packing material. Went to my local dealer and bought some O'neal packing. I then wrapped the packing around the pipe core and re rivited the pipe.

Now 4 trackdays later.....I have zero packing material in my pipe?? Also all the front rivets are loose again??

Is this normal?
should I have kept the mesh screen/steelwool looking stuff?
Have I hurt my bike?
What should I do to fix this issue?

TIA:worthy: :worthy: :worthy:

Sorry for the long post.

  • Ztard

Posted August 14, 2007 - 03:25 AM



  • grayracer513

Posted August 14, 2007 - 06:29 AM


Did you use 4-stroke packing? There's a difference.

Yes, you should have kept the wire mesh/steel wool. Try it again with some FMF stuff.

  • Ztard

Posted August 14, 2007 - 06:55 AM


Crap! I knew I should have kept that mesh stuff.......off to the shop

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Ga426owner

Posted August 14, 2007 - 07:08 AM


Crap! I knew I should have kept that mesh stuff.......off to the shop

sounds like too much back pressure w/o the mesh insert caused the rivets to expand and loosen....I also wondered about this...
Here is a company that has some higher quality packing
Pipe manufacturers will tell you to repack every 15hrs....I find that I can go longer than this with proper care on the packing....namely keeping all moisture out of the end on the pipe. I buy the rubber corks from Home Depot/Lowes that fit snuggly on the end of the pipe...2-6 bucks. :thumbsup:

  • tnl

Posted August 14, 2007 - 07:14 AM


I went thru this a week ago. do a search and you'll find a hour's worth of posts on this. But, I saved my "mesh" and installed fresh 4 stroke packing and have 3 hours on it and I don't have any problems. Did you use the correct drill bit size when you drilled the rivets out? Maybe you drilled the hole one size larger than needed?

  • skubasteev

Posted August 14, 2007 - 07:16 AM


Also make sure you are using steel rivets. I used aluminum ones before and they only lasted 2 races.

  • Ztard

Posted August 14, 2007 - 07:52 AM


Thanks for the comments, stopped by a local shop and got a quality 4 stroke repack kit even got more steel mesh stuff. Good tip on the rivets, I used aluminum last time.

Related Content


Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

05 yz450f not fast enough by RedeyeYZ

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

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

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

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