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TOPIC: RT Crankshaft Shim

RT Crankshaft Shim 13 Jun 2019 09:54 #21

  • PMK
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DEET wrote: In MY experience, there is no binding that occurs when correctly assembling an engine.

I use the DEET crankshaft installation tool to pull the crank through the bearing.
First install the primary side with shim.
Install transmission.
Apply Yamabond to both cases.
Place left case over shafts.
Use crank tool to pull the magneto side of the crank through bearing.
Use plastic hammer to "help" the transmission shafts through their bearings. When the cases are together, stop pulling the crank.
Bolt cases together.
Use crank tool to tug on the primary side one last time to make sure the crank is snug against the bearing.
Install o-ring and primary gear. Install nut. After installing the clutch basket, torque the crank nut.

No binding... magneto side floats in and out with temperature (or so I assume).... engines lasts another 50 years....


Absolutely agree. Even though this deviates from the shop manual by assembling into the right case, it makes good practices to use the crank installer to install the left side case.

As for heat, operation or whatever settling the bearing race on the left crank half, it seems following the manual will initially bind the crank bearings.

As for the shim, I now tend to agree, it is likely to help center the crank and less about a form of preloading the bearings.

Bear with me guys, after building my friends OSSA MAR engine a few weeks ago, I am shim paranoid. Every shaft, and I mean left and right side of the crank, the gearbox shafts, the shift drum all get shimmed in those motors. You do a dry run assembly several times, each time measuring the shaft end play. Even need to make a dummy bearing for checking the crank clearance. Then you shim each shaft, assemble each shaft on a second dry run to verify the correct clearance.

Once all the shims are sized and placed, then you build the thing for real. The dummy bearing is a crank bearing that you carefully open the ID clearance for a close slip fit that allows the crank to be slid left or right to measure end play.

So. For the RT2, build as I have for decades and accept the manual as a guide rather mandatory...

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RT Crankshaft Shim 13 Jun 2019 09:56 #22

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Is the DEET crank install tool Yamaha DT / RT specific or similar to most production tools? If it is a proprietary design not to be shared that is ok too.

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RT Crankshaft Shim 13 Jun 2019 10:52 #23

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Here is the tool...

www.yamaha-enduros.com/index.php/forums/...tallation-tool#21265

I sell them with all adapters, or bike specific.

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Where the Yamaha Enduro is still a current model...

RT Crankshaft Shim 13 Jun 2019 11:35 #24

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I just freeze the crank, put the LH case in the oven @ 280 for a few minutes & drop the crank through the bearing. B4 this all clearances are measured for the crank and the tranny, and shims ready. Yamaha runs the tranny tight, so take your time on measuring it. All the ways Deet mentioned are the correct ways to measure.

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RT Crankshaft Shim 13 Jun 2019 15:28 #25

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Pillsbury wrote: I just freeze the crank, put the LH case in the oven @ 280 for a few minutes & drop the crank through the bearing. B4 this all clearances are measured for the crank and the tranny, and shims ready. Yamaha runs the tranny tight, so take your time on measuring it. All the ways Deet mentioned are the correct ways to measure.


Yes, that could work if installing the crank per the manual. Seems as these guys have stated, they build into the right side case, so it would be difficult to fit the frozen crank into the right case and then handle a heated left case half being positioned, aligned and then closed onto the Yamabond. Plus this would also require letting the case cool to room temp for proper tightening of the case screws.

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RT Crankshaft Shim 13 Jun 2019 18:33 #26

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I gravitate towards the 175's... not sure what the manual says but it's nearly impossible to assemble the trans into the left case. Very easy to assemble into the right case. So that's how I've always done it. When you press the left case onto the crank, no worries about pressing too far... just go until the cases mate together. Never had a problem.

I don't remember the last time I did a 250/360... but I likely did it the same way. Assemble into right case, add left case.

Now I'm going to have to look at the 250/360/400 manuals and see what they say.

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