Crankshaft bearing question

[briandr]

Hey all,

Fighting my way through a rebuild and have hit a small snag. I've changed out crank cases and have been trying to make sure that I'm putting the correct bearings in. The bearings I've pulled out of the old engine have markings, but they don't match anything I'm seeing in the manual. I should see things like 12229-01 D00-0A0, but instead they all have F-780 and then either 535A, 838C or 494H. They look in decent shape so I'd like to reuse them, but not if I can't figure out which ones to use. Thanks in advance!

[burning1]

Worst case, you can measure the journals using a micrometer or with plastigauge.

My recollection is that the stamps aren't in an obvious location. Both of those numbers seem wrong for a bearing stamp.

[sledge]

OEM bearings come in 4 sizes, they are colour-coded and have a little dab of paint on one side to identify which size is used, black brown green and yellow....(I think.)

If the dabs have worn off you need to follow the procedure in the manual and cross reference the numbers on the crank webs with the letters stamped into the case directly behind the rear wheel on the chart. This will tell you what colours are needed and in which location the bearings sit sit...Or go to your dealer with the info and let them do it 

Unless you know the history of the bike I would double check the sizes rather than replace like for like on the basis someone else may have been in there before you and fitted incorrectly sized items.

[briandr]

Thanks, I appreciate the responses. I'll be up at the dealer later this week picking up (hopefully!) the last parts I need, I'll ask them to measure them with a micrometer. The tolerances are too small for the micrometer I have, but after having a crankpin bearing go on me too soon after getting the bike, I'm not interested in taking chances!

[burning1]

OEM bearings come in 4 sizes, they are colour-coded and have a little dab of paint on one side to identify which size is used, black brown green and yellow....(I think.)

Problem is, he's changed crank-cases, which means that the bearings he already have may not be the right size for the crank/crankcase combo he has.

If you're not worried about checking for wear or damage, the easy solution is to match the markings on the crank and crankcase, to the chart in the repair manual. This can produce bad results if the crank or crank-case is out of spec, but with known good parts it should be close enough.

If you want to measure, cheapest method is to use plastigauge. It's available for a couple bucks from any auto-parts store.

Word of advise: You only need to tighten up the crank bolts when using plastigauge. The case bolts break easily, and it's best not to tighten them more often then necessary.