1198 Rod Bearings

ThatOne1198 · Feb 23, 2025

Ok so I am rebuilding the engine out of my 2010 1198S and need to get new rod bearings. I know that my crank is stamped with a B and so are both of my conrods, according to the manual it would be blue/yellow bearings. I am struggling to find any useful info on how to determine which ones I need and so far it just looks like I have to order the bearings and use platigauge to find out if they fit right or not. Can anyone shed some light onto what I need to be doing to get it done correctly?

CanyonCarver · 2025-03-06T14:27:17-0800

ThatOne1198 said:
Ok so I am rebuilding the engine out of my 2010 1198S and need to get new rod bearings. I know that my crank is stamped with a B and so are both of my conrods, according to the manual it would be blue/yellow bearings. I am struggling to find any useful info on how to determine which ones I need and so far it just looks like I have to order the bearings and use platigauge to find out if they fit right or not. Can anyone shed some light onto what I need to be doing to get it done correctly?

The service manual should direct you to taking measurements. You'll need an ID micrometer and an OD micrometer, measure the difference, divide by two, remove the clearance and that is the bearing thickness. That thickness will fall into a range that is a certain color bearing shell. Remember, plastigauge is QC check, you don't build an engine with it.

Now for how Ducati and everyone else slaps these things together:

As crazy as it sounds, that blue/yellow concept came from them building the motor off the crank. They averaged the two crank journals, if it feel within a certain range it was a B. Then then grabbed two B conrods and threw in the blue/yellow shells. They never checked tolerances manually nor had the benefit of modern QC during manufacturing of the parts. That is why on the L-twins you either had one that lasted or you had one that let go before 3000 miles. The issue is tolerance stacking.

baggerman · 2025-03-06T16:22:30-0800

CanyonCarver said:
The service manual should direct you to taking measurements. You'll need an ID micrometer and an OD micrometer, measure the difference, divide by two, remove the clearance and that is the bearing thickness. That thickness will fall into a range that is a certain color bearing shell. Remember, plastigauge is QC check, you don't build an engine with it.

Now for how Ducati and everyone else slaps these things together:

As crazy as it sounds, that blue/yellow concept came from them building the motor off the crank. They averaged the two crank journals, if it feel within a certain range it was a B. Then then grabbed two B conrods and threw in the blue/yellow shells. They never checked tolerances manually nor had the benefit of modern QC during manufacturing of the parts. That is why on the L-twins you either had one that lasted or you had one that let go before 3000 miles. The issue is tolerance stacking.

Exactly. My 1098 had too much rod clearance and the end float on the crank had way to much preload. I could hear the rods were loose, so took it apart and discovered the crank. I don't use plastigauge. I torque the rods to the first setting in a soft jawed vise and then measure the journal, zero a bore gauge in the anvils of the mic I used. Then when you use the bore gauge in the rod it reads out the clearance. The colored shells vary. They ranges sorta overlap so a big of one size could actually be the same as a small toleranced next size. Buy extra shells if you want to be precise. New rod bolts always. I prefer to measure stretch then the weird stuff in the manual. I usually buy a couple of extra rod bolts in case I get a stretchy one.
Check the crank end float. The crank should be shimmed such that at operating temperature the ball bearings have .001 to .002 inch preload. No more.

1198 Rod Bearings

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