As a regular motorcycle rider, you know what to expect from your bike when you're on the road. You also know how to recognize when your bike isn't responding the way that you expect it to. You may not know exactly what's wrong, but you can tell when something's different. If you're noticing issues when you shift gears, it may mean that there's an issue with the transmission. Here are a few of the common transmission issues you might encounter with your bike.
Worn Bearings or Gears
The more you ride, the more wear and tear the bike's transmission will be subjected to. Over time, the wear can cause the space between the gear teeth to expand. When that happens, it will cause clashing and grinding whenever you shift. That sound is a warning sign that your transmission is in need of new gears. If the problem is the bearings, you'll start to hear a consistent growling noise from the transmission even when it isn't shifting. Sounds like that usually indicate that the countershaft bearing or mainshaft bearing may be failing. You'll want to address symptoms like this right away, because a bad bearing will need to either be lubricated or replaced to avoid damaging the gears. Since this type of repair requires disassembling the entire transmission, it's best left to a mechanic unless you have experience in transmission repair.
Damaged Shift Mechanism
The shift mechanism transfers the shift lever's motion to the slider to engage the transmission and change gears. It is drum shaped and spring loaded. Over time, the spring will wear. If it does, the transmission won't engage properly, which can lead to a risk of transmission failure due to friction from the shift forks. If the shift lever feels limp or seems temperamental, it may be time for a replacement.
Bent Shift Fork or Slider
The shift fork is attached to the shift mechanism and slider. When a shift fork is bent, it may cause binding in the slider when you shift. If you have found that a specific gear isn't functional or won't stay engaged, it likely means that the shift fork or slider are damaged. This usually only happens to one gear at a time, so the rest of your gears should operate properly.
The transmission on your motorcycle is delicately balanced with gears, bearings and many other moving components. If you have any reason to believe that the transmission isn't responding properly, you should have it evaluated by a mechanic (such as one from American Transmission Center). If you're seeing signs of one of the problems listed here, let him or her know so that they know where to start with troubleshooting.