WR Pipe Mod

Pistonfat Rider put together these excellent pictures and steps to open up your WR 450 F exhaust pipe.

1. drill around existing tailpipe with 3/16" drill. [image:4721]

2. grab onto tailpipe with pliers, give it a twist [image:4722]

3. pull it out from the muffler [image:4723]

4. mark out a hole to suit the new tailpipe (trace around the pipe) you intend to use. I used 1.5" stainless tube. File out the hole smooth with a half round file. The metal is thin and easily filed [image:4724]

5. this is the new tailpipe I made. It is 22cm long. I had this lying around the garage for another project. It already had one end flared. [image:4725]

6. insert new tailpipe hard up against the existing baffle, making sure the it lines up with the hole in the baffle. It will make sense if you look inside the muffler. About 3cm will ptrotrude from the end of the muffler, but it's up to you how much you want to stick out. I judges this length from looking at a Staintune muffler. It will be at a slight angle, but this is normal [image:4726]

7. side view of inserted tailpipe [image:4727

] 8. weld tailpipe into muffler. This was done on a TIG welder by a mate. It's a bit tough, but it was free. [image:4729]

9. top view of welded tailpipe [image:4730]

10. side view of welded tailpipe showing the angle [image:4731]

11. this is an insert I made from a urethane suspension bush. it is secured in by a small self tapping screw underneath. I use this when playing around in the backyard so as not to annoy the neighbours. Whilst the modified tailpipe isn't excessively loud, with the insert fitted, it is quieter than the stock muffler. [image:4732]

12. the is the urethane bush that I used for the insert [image:4733]

This is a very cheap and easy mod to do. It will give you more power, better response and it sounds REALLY good. This mod uses all the existing baffles inside the muffler, hence it is not excessively loud. On my 04 model WR450, I am usung 165MJ, 48PJ and F/S turn out 2.5 turns.