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Assembling the Crankcases

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Written by Randy Fox   
Saturday, 03 November 2007

Filling the Crankcase

 

Installing the Crank Assembly

Oil the bearing surfaces of the crankshaft using assembly lube. Also dribble some assembly lube onto the connecting rod bearings, as best you can. Then, carefully install the crank assembly into the right-side case. This is a very heavy assembly (50 pounds). You must slowly guide the crankshaft through its bearing without binding. Be careful you don't distort or damage the bearing; easy does it. Also, be sure to engage teeth with generator shaft.

 

Installing the Transmission

Next, oil the bearing surfaces of the transmission shafts using assembly lube.

 

transmission, gears, Yamaha Road Star

 

Install the transmission assembly into the right-side case. Depending on whether or not the transmission assembly has been kept wire-tied together during this project, do the following:

  • If still wire-tied together, then, while holding both shift-fork shafts from sliding out, carefully install the assembly into the right-side case. After ensuring that all five shafts are seated into the case, remove the wire-ties.
  • If the transmission pieces are apart, install them in the following order (as viewed with the crankcase in standard orientation):
    • Left shaft (main axle) and gears
    • Right (drive axle)
    • The three shift-forks
    • Shift-drum
    • Both shift-fork shafts while aligning the forks into shift-drum, and on their gear sleeves
  • See photos above and below

Check the transmission function by rotating the gears and sliding the shift-forks. Everything should move without binding, and look like the photos below. Also, refer to the service manual.

 

transmission, gears, Yamaha Road Star
View from engine's bottom

 

transmission, gears, Yamaha Road Star
View from engine's rear

 

transmission, gears, Yamaha Road Star
Overhead view

 

Dribble assembly lube onto the transmission's sliding and rotating surfaces.

 

Installing the Oil Pump

Next, install the oil pump. Be careful of the strainer screen; it is delicate. Torque with 7.2 ft-lbs. Remember, there are three black bolts for the pump, plus the two brass-colored bolts for the strainer. See photo below.

 

Oil pump, Yamaha Road Star

 

Finishing the Crankcase Assemblies

Insert alignment dowels into the crankcase, and test fit the left case onto the right. As you do this, watch the transmission shift-drum-assembly. It might need a bit of rotating to align with the (puzzle-piece) hole pattern in the left-side case.

Rotate and push/pull all the shafts to be sure they work smoothly, without excess play. If something binds or feels sloppy, DO NOT PROCEED. Stop, examine, and fix the problem, even if it means starting all over.

Separate the left case from the right, and remove the alignment dowels.

Now, insert the crossover tube per the photo below. Be sure its two O-rings are installed. If you use a plastic dead-blow hammer, as I did, be sure to tap very lightly.

 

crankcase, crossover, Yamaha Road Star

 

 
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