Bearing

[millosman]

Would have been nice if Yamaha listed the thickness of the bearings and the ID of rods and case main bores (like every other major Japanese manufacturers factory workshop manuals). Then (having the tools and ability) you could actually measure conrod/main pins and actually come up with real #'s.
I agree with what was said about the rod big ends being out of round. I have only worked with 3 sets of OEM rods but every set required a good amount of cap cutting and resizing. I run Carrillo A beams in my FJ. Plenty strong and lighter than the H beams.....best of both worlds.

Hi JMR
I'm looking to have my con-rods resized as my oil clearances are still too large at just over 0.04mm with new shells installed.
You mention here that you have resized the standard rods before. Can you offer the right info to resize them to? I measured mine and obtained readings in the range 40.03mm to 40.09mm, the accuracy of the bore gauge I was using being to the nearest 0.01mm.
The largest range found on a single rod was 0.04mm so as you suggested, they are out of round.
Converted to inches the size ranges from 1.5759843" to 1.5783465".
So what should I machine them to please?
Hope you can advise. Many thanks, Andy

[millosman]

Your numbers appear to be correct in reference to the bearing selection. Here are few points to consider.

Send a photo of the crankshaft and case numbers please. Another set of eyes can't hurt at this point.

1) I do see you have added grease to the journal. That grease is going to take up space and will compress the plasti-gage more and offer erroneous readings. The journal and bearing should be dry when using plasti-gage.
2) The FJ rods are notorious for not being round on the big end. Have you checked to ensure they are round? I never install a rod without cutting the cap & rod and honing them back to round.
3) I always align my plasti-gage at the top of the rod, inline with the beam. That way if there is any taper in the bearing at the parting edges, I don't get erroneous readings.
4) If the clearances are too great after that, then the crank is worn and requires replacement.

I too have a ball end micrometer for measuring bearings. But as Bill mentioned, it is not graduated fine enough to be able to measure the difference in the Yamaha bearings.

Randy - RPM

Hi Randy
Can you tell me the dimension to resize a No 4 conrod to? Mine are out of round by up to 0.03mm.
Thanks
Andy