How to Size the Crankshaft Bearings on a Yamaha R6 

Whether it's a bent piston rod, a worn crankshaft, or a complete engine tune and rebuild, you'll need to replace the crankshaft bearings of your Yamaha YZF-R6 if you're working on the bottom end. 

Replacing the crankshaft bearings on your R6 motorcycle means you're going to have to size them too, and this guide will show you how to get it done.

Sizing Yamaha R6 Bearings

You don't need any tools to size the crankshaft bearings on your Yamaha R6, but you do need the bearing ID numbers found on the crankshaft, piston rods and crankcase of your R6's motor.

Step 1. Note down the crankshaft bearings number. The 9-digit number is stamped on the end crankshaft counterweight. The first five numbers relate to the main journal bearings; the last four numbers relate to the connector rod bearings.

EXAMPLE: 211221111

Step 2. Note down the piston connector rod bearing numbers. The connector rods may have different numbers, or all share the same number. Each number is stamped across the con rod and the con rod's end cap.

EXAMPLE: 5H, 5H, 5H, 5H

Step 3. Write down the main bearings number, which is stamped on the lower half of the crankcase at the back. If the number is a single digit, you should use that same number for all the crankcase main bearings.

EXAMPLE: 5

Step 4. Size the Yamaha R6 connector rod bearings by taking the first connector rod bearing number and subtracting the first crankshaft/connector rod bearing number from it. Repeat this for all four con rods.

EXAMPLE: 5H - 1 = 4

Using the Yamaha R6 bearing color code chart (pictured below), you can determine the bearing size for each connector rod.

EXAMPLE: 4 = Green Bearing

Step 5. Size the Yamaha R6 main bearings by taking the crankshaft/main journal bearing number and subtracting the main bearings number from it, then subtracting 1 from that number. Repeat this for all four main bearings. 

NOTE: Having to subtract the 1 is a quirk of Yamaha's bearing sizing system. Don't forget to subtract the 1 after you've subtracted the main bearings number from the crankshaft/main journal bearing number or your bearing sizings will be inaccurate.

EXAMPLE: 5 - 2 - 1 = 2

Using the Yamaha R6 bearing color code chart (pictured below), you can determine the bearing size for each main bearing journal.

EXAMPLE: 2 = Black Bearing

Now that you know the Yamaha R6 bearing sizes for your engine, order them from Partzilla and take advantage of our discounted prices.

With your Yamaha R6 bearings sized, you're now ready to install the crankshaft and drive axle into the crankcase. Watch the video below to see how to rebuild the bottom end of a Yamaha YZF-R6.