1978 Yamaha 650 Special

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Keeping a 25+ year bike running takes some attention.  Here are some Tips and Tricks I've picked up from the experienced folks at bike shops and on the web.  Also check out my XS650 Links page for some really great sites!

  New Engine !!!


I just bought a new (old) engine from Spyder at Black Widow Choppers.  This is my new Winter Project.  I'll try to keep things updated as I progress.

Planned Engine Projects:

With the new-found test bed engine, I hope to explore some of the refinements available for the XS650 engine:

  • 270 Degree Re-Phase of Crank and Camshaft
  • Electronic Ignition
  • Permanent Magnet Alternator
  • Tapped Ports for Oil Cooler and High-Flow Oil Pump

If anyone has helpful hints that they'd like to share, I would appreciate any suggestions and comments.  E-Mail Me.


Planned Chassis Projects:

Also on the agenda as time and cash permit:

  • Swing Arm Bushings and Tapered Roller Bearings for Steering.
  • Front Fork Brace and Swing Arm Reinforcement (maybe a few inches stretch as well).
  • Fitting a larger tank from an XS750.
  • Check out the Travelcade Bucket Seat that was added.


XS750 Tank and Motor "In the Raw":

Here is a look at the XS750 Tank ground down to steel, and the approximate fit-up to the motor.  The Sketched Flames / Stripe (click to see sketch) on the tank is a first thought - the lower stripe would be clear coated bare metal with a "brushed" finish, and the flames would be a Translucent Candy Orange showing the "brushed" grain through - the rest of the tank could be last year's Midnight Blue Metallic, or I might switch to Triumph Yellow.  Comments are Welcome.



  <-- The "New" XS750 Tank "before"



XS650 Alternator (Left Side Cover):

Here is a look at what's under the Left Side Cover of the XS650 engine.  The XS650 has an excited field alternator, which means the magnetic field is generated by battery voltage instead of permanent magnets.  If you have a weak battery, you get a weak field, and weak spark, and hard starting...  There are a few ways to install a Permanent Magnet Alternator on the XS650, I'll be investigating them and providing results here.


Note the seeping Clutch Pushrod Seal to the left of the Chain Pinion (Sprocket).  This is the most common oil leak point on the XS650.  This engine has the standard 17-tooth front sprocket installed.  Installing an 18-tooth front sprocket decreases engine RPM at highway speeds, thus reducing vibration during highway cruising.  You need to remove the Chain Guide off of the Shifter Shaft (rusty thing sticking out just below the Chain Sprocket) to clear the 18-tooth pinion.

MikesXS.com has replacement Clutch Pushrods, Bushings and Seals, as well as 18-Tooth Sprockets and Chains.


XS650 Clutch (Right Side Cover):

Here is a look inside the Right-Side cover of the XS650 engine.  Note the clutch pack in the center (or centre, depending on where you're reading this...).  The smallest gear ahead of the clutch (to the right in the photo) drives the oil pump and tachometer.  You can see the gear selector mechanism behind the clutch pack - this is driven by a rod that travels through the engine from the left side (where the shifter pedal is attached near the chain sprocket).  In the overall photo you can barely see the gear (to the rear, or left of the photo) that is driven by the kick start mechanism.


Below is a different view of the shifter mechanism, and also the inside of the Right Side Cover with the Oil Pump and Tachometer drive installed.  (Click Photos to enlarge them in a new window.)






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This site was last updated 01/08/06