Rather than jumping brands to chase a little extra power, we decided to see how much more punch we could extract from a Yamaha YZ65, a bike long known for being one of the most reliable junior racers on the market. So instead of changing bikes, we looked into a few pipe options and settled on the GYTR system. Fitting this pipe is relatively straightforward, so let’s get into it.
- LIFT IT
Start by placing the bike securely on a pit stand and removing the seat. There’s an 8mm hex-headed bolt at the rear of it.
- SIDEPLATE
Remove the right-side numberplate. The sideplate is secured with two 8mm hex-head bolts — one in the side and one in the top.
- SILENCER
Remove the muffler by undoing the 8mm bolt at the top, then twist the silencer back and forth while pulling until it comes free.
- CHAMBER
Remove the expansion chamber by undoing the 8mm bolts at the rear of the chamber and at the front. You will also need to use a spring puller to remove the header-pipe springs holding the chamber to the exhaust port.
- REMOVE O-RINGS
Remove the O-rings from the standard expansion chamber, clean them, apply grease and fit them into the header of the new pipe. If they are damaged in any way, replace them with new ones.
- SEAL IT
Remove the rubber joiner from the old silencer and fit it to the new one. Then remove the rubber donut and steel collar from the old silencer and fit them to the new one.
- MOUNT UP
Fit the new expansion chamber to the bike and loosely install the mounting bolts. Use a spring puller to refit the exhaust springs so they hold the expansion chamber tightly to the exhaust port.
- MUFFLER
Fit the silencer and install its bolts loosely.
- TIGHTEN BOLTS
Once the expansion chamber and silencer are sitting in the correct positions, tighten all mounting bolts.
- REFIT SEAT
Once the pipe is tightened into place, refit the sideplate and seat. Go for a ride and check the jetting.
TIPS
DO’S
• Always use new rubber O-rings and seals if the old ones are showing damage.
• Grease the seals and O-rings so they slide into place easily.
• Use a spring puller on the exhaust springs.
DON’TS
• Over-tighten any mounting bolts.
• Force any parts into position with excessive force.
• Reuse damaged or worn bolts, O-rings or seals.
TOOLS:
Spring puller, spanners, T-bars, ratchet, sockets, screwdriver, grease.
BEWARE
If the exhaust isn’t fitted correctly, this can drastically affect the power of the bike.
BREAKOUT
EXPANSION CHAMBER CARE
• Never leave the pipe covered in mud or it will start to rust.
• Clean unpainted pipes using soapy water and a green scrubbing pad.
• Coat the pipe in silicone spray after washing to help prevent rust.
• Always replace worn or damaged seals or O-rings to stop two-stroke oil leaking all over the bike.
• Regularly repack the silencer.
• If storing a pipe, rub it with automatic transmission fluid before putting it away — this will protect it longer than penetrating oil.
