Problems with Yamaha WR forks bottoming out?

If you have customers complaining about excessive bottoming on 2006-2011 Yamaha WR250’s and 450’s this information may be of help.

The evolution of the Yamaha Off road fork took a departure from the YZ design in 2005. While the YZ got the new twin chamber fork the WR was struck a cruel blow from the accounting department and received a little 25mm cartridge with a resulting less than ideal action.

Many of the top pro enduro riders were fitting the YZ forks but it's not a cheap swap and you may not like the MX settings in the bush. For 2006 the WR range received a bigger 28mm cartridge (similar to a mid 90’s YZ but with a different style of compression base valve) commonly known as a poppet valve.

Most people - especially heavier and faster riders - agree that when the fork is new the action is excellent. Plush on small bumps and absorbing tree roots and rocks with ease. Only after 10 or so hours does the performance seem to drop off - the fork hangs lower in the stroke - loses it’s nice feel and starts bottoming hard. Lifting the oil level does help but our fork dyno tests have revealed a loss of dampening is the culprit. The poppet valve loses free height - critical to making the system work. While the spring can be shimmed higher every time this happens there is a kit available. 

Our kit and settings were developed with the help of some top enduro riders and Lyndon Heffernan from the Academy of Off Road riding so you know it’s suited to Aussie conditions.. The kit makes the fork action much more consistent. Some of the testers even preferred the modified WR fork to the YZ fork!

The kit comes with a range of shims to make different settings for different riders. All instructions are included. A complete replacement assembly has also been developed for an even simpler replacement.