Tunnel Dump Questions

I just did..

I just did one of these tunnel dump mods on that same side exit system in the shop last week.

Order a 3" mandrel bent 90 degree pipe section from an Auto supply or Muffler shop. It needs to be mandrel bent with a tight radius.

Pull the 3 springs and remove the muffler and pipe. Cut off the connection flange directly where it enters the muffler, use a zip style cutoff wheel on grinder, cut tight to the muffler and be careful not to jam it. Put the flange section back onto the discharge pipe with springs in place. Hold your mandrel bend piece in place to determine lengths and where to cut. Visualize where you want the hole to exit through into the tunnel, slightly right of the center located coolers, approximately 1/2" in from outer edge of tunnel. Mark the hole location. Cut out the hole. Again hold your mandrel bend in place and re-estimate the length for cutting.

It is pretty straight forward, just measure twice cut once. Straight 90 degree to the pipe cuts worked well for me. Leave the exit end about a half longer to extend down into the tunnel a half inch.

I welded new supports for the heat shield onto the new pipe section so it was retained in the original location. Also wrapped the new pipe with 2" heat wrap. approximately 6' long. Wired the heat wrap in place.

Order a new side panel from your Yamaha dealer and project complete.

**the mandrel bend is the key, if you try to bend 3" pipe that tight it well crease and kink up.

Good luck!!