Ask Norton: XS650 Clutch Engagement

Ask Norton MikesXS Yamaha

Q:

Why is my Yamaha XS650 so difficult to shift? It seems to want to creep forward with the clutch engaged at stop lights.

A:

It sounds like the Primary Driven Gear isn’t engaging properly on your Yamaha XS650. This is not an unusual situation, and is likely the result of normal wear and tear. There are two possible causes for this problem, one of which has a simple fix, while the other will require a little more mechanical aptitude. The best-case scenario is that your clutch simply needs to be adjusted, and the worst-case scenario is that the fingers on your Primary Driven Gear (also known as a clutch hub basket) are worn and require servicing.

Always check the simplest solution first. The XS650 clutch is adjusted via a worm gear located on the left side of the engine. When the worm gear is adjusted improperly, the pressure plate is prevented from expanding the full distance needed to allow clutch engagement. Adjust the clutch worm gear assembly to the factory specifications.  While you’re in there, take the opportunity to clean and inspect the worm gear and its parts. The metal worm gear turns a plastic adjuster, which can wear out. Replace worn parts as necessary.

If your XS650 Primary Driven Gear still will not fully engage, you must service it. The Primary Driven gear has extruding portions that capture the fiber and steel clutch plates and prevent them from rotating. The outer tangs on the fiber clutch plates apply constant pressure against the sides of these capture fingers, causing indentations to form. Over time, the side wear on the fingers becomes deep enough to prevent the fiber plates from being fully released. The resulting uneven release of the clutch plates prevents the inner boss from separating from the clutch hub basket. The net effect is that the main axle is not allowed to rotate. The transmission components do not have the movement they require to relieve pressure, and the internal gears are unable to locate their correct positions.

Follow these steps to eliminate the indentations on the Primary Driven Gear fingers. First, drain the engine oil from the crankcase. Remove all components necessary to allow you to remove the right-hand side engine cover, then disassemble the clutch assembly. Once disassembled, inspect the Primary Driven Gear side fingers for noticeably worn areas. To smooth the indentations, file them down using a large-width, double-cut bastard file. Remove only the minimal amount of surface material needed to create a smooth and even surface, and try to keep the finger widths parallel. Take the opportunity to clean and inspect all clutch components, and replace any worn parts as required.

The hard shifting that results from a maladjusted clutch can cause abnormal wear on the moving parts in your transmission, so be sure to perform these maintenance chores at the intervals specified in your maintenance manual. Please check MikesXS.net for any clutch parts that you find need replacing while performing this job, and be sure to check back for future posts detailing maintenance and repair procedures that pertain to your XS650. As always, feel free to contact our Customer Service Team with any technical or part fitment questions you may have regarding your vintage Yamaha.

Ride on and enjoy,

Norton

Customer Service Team

customerservice@mikesxs.net

www.MikesXS.net

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