Author Topic: 500/550 four crankshaft and connecting rod bearing selection  (Read 3188 times)

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Offline kranta

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500/550 four crankshaft and connecting rod bearing selection
« on: November 03, 2015, 10:28:22 PM »
So. I checked my bearings with plastigauge and if clearence is bigger than 0.08mm on connecting rods and crankshaft bearing should be replaced and my crankshaft clearence is 0.050-0.063mm but how i know what is next side of bearing? is it stock= 36.000-36.008 and if clearence is bigger than 0.08 next side 36.008-36.016m? And does the connecting rod bearing selection goes same like the crankshaft bearing selection?

Sorry bad english

Offline HondaMan

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Re: 500/550 four crankshaft and connecting rod bearing selection
« Reply #1 on: November 03, 2015, 10:45:30 PM »
So. I checked my bearings with plastigauge and if clearence is bigger than 0.08mm on connecting rods and crankshaft bearing should be replaced and my crankshaft clearence is 0.050-0.063mm but how i know what is next side of bearing? is it stock= 36.000-36.008 and if clearence is bigger than 0.08 next side 36.008-36.016m? And does the connecting rod bearing selection goes same like the crankshaft bearing selection?

Sorry bad english

The bearings can be determined 2 ways:
First way is: try to see what color of paint is on the edge(s) of the present bearings. It is faint, but will be a color like Yellow, Green, Brown, or Black. Then get bearings one size smaller.

Second way is: find the markings (letters) on the crankcase (bottom side, usually on the front lip of the engine case) and then find the corresponding numbers on the crankshaft weights (sometimes these are very faint, but are etched with a stamp or a buzzer-engraver). The bearings were originally selected via these letters (sizes A, B, C, or D), so you can select the next size smaller ones from there, too.

Even if the engine was worst-case, though, the difference between the 4 bearing sizes is only 0.0004" (0.01mm) per step size, or 0.0012" (0.04mm) for the entire range of bearings. Since these engines like having tight bearings, I sometimes purposefully select too-tight bearings myself, then break in the engine carefully, to help them develop more power. If the bearing clearance is as little as 0.0004" (0.01mm) it will be hard to start the first time, but after that it will always enjoy high oil pressures, and will be very smooth! I just did this with my own CB750, setting the clearance to 0.0006"-0.0008" across all crank and rods. It is VERY smooth, and develops considerably more midrange power than before I rebuilt it.
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Link to website: SOHC4shop.com  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline kranta

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Re: 500/550 four crankshaft and connecting rod bearing selection
« Reply #2 on: November 03, 2015, 11:26:55 PM »
Ok but if clearence is smaller than 0.08 what bearing i should get and what i even do with this clearence measurements if its 0.08 is it then stock bearing? And back side of the bearing got marks2K-A   STD so what side is this bearing?

Offline HondaMan

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Re: 500/550 four crankshaft and connecting rod bearing selection
« Reply #3 on: November 04, 2015, 09:14:24 PM »
Ok but if clearence is smaller than 0.08 what bearing i should get and what i even do with this clearence measurements if its 0.08 is it then stock bearing? And back side of the bearing got marks2K-A   STD so what side is this bearing?

That particular mark (2k-A) is a manufacturer's mark: the STD is found on almost all of the bearing shells, regardless of size.
The various sizes are marked via colors on the edges of the bearing.

The bearing thickness is based on 1.50mm material for 0.00 clearance. Thus, 1.496 thickness = (1.50-1.49)= 0.01mm clearance.

You may have to measure the ID of the crankshaft's holes in the cases and the OD of the crank journal to determine which bearing you need, if the color is not found on the bearing shell. Be sure to do this with bore ID and micrometer tools, do not try it with calipers (they will not work correctly).
« Last Edit: November 05, 2015, 04:45:13 PM by HondaMan »
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: SOHC4shop.com  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline HondaMan

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Re: 500/550 four crankshaft and connecting rod bearing selection
« Reply #4 on: November 05, 2015, 04:44:44 PM »
You may have to measure the ID of the crankshaft and the OD of the crank journal to determine which bearing you need
Typo, no?
Oops!
Yeah, it will be hard to measure that...fixed it, thanks,Cal!
 :-[
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: SOHC4shop.com  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).

Offline HondaMan

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Re: 500/550 four crankshaft and connecting rod bearing selection
« Reply #5 on: November 05, 2015, 08:47:48 PM »
Just a case where we all pay such close attention to your wisdom, Mark

Ah..careful there, Cal: Knowledge, I have a little. Wisdom: not so much!
;)
See SOHC4shop.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book
Link to My CB500/CB550 Book: https://www.lulu.com/search?sortBy=RELEVANCE&page=1&q=my+cb550+book&pageSize=10&adult_audience_rating=00
Link to website: SOHC4shop.com  (Note: no longer at www.SOHC4shop.com, moved off WWW. in 2024).