Topic: cb550 cases/ cb650 crank bearing selection-- help please!!!

[paulages]

both have the same spec parameters, but the crank i'm using (650) obviously didn't mate with the cylinders (550) before. after plastigauging and deciding that it was too inaccurate, my machinist and i mic'ed the journals and used a cam bore gauge to measure the housing bores. i came up with strange numbers:

                              1                 2                 3                4                5
--------------------------------------------------------------------------------------
JOURNALS               1.299             1.299           1.299          1.2985          1.299

CASE BORES           1.4171            1.4167          1.4171        1.4171         1.4172   

the journals look good, though the actual measurement put it in a different category than the number stamped on it for the selection chart. the case bores are .0006-.0001 smaller than the smallest allowable measurement in the selection chart. for reference, here is the chart:

                           MAIN JOURNAL OD  size code letter and dimension
                           letter A                               letter B
                           1.2988-1.2992                   1.2944-1.2988 in.
-------------------------------------------------------------------------------------
CONNECTING ROD
code number and
dimension

letter A
1.4173-1.4176 in.      yellow (D)                        green (C)

letter B
1.4176-1.4179 in.      green (C)                         brown (B)

letter C
1.4179-1.4183 in.      brown (B)                         black (A)
-------------------------------------------------------------------------------------

as the charts don't give actual dimensions of the bearings, we decided to install the bearings, torque the cases down, and re-measure the clearances off of the existing bearings. the cam bore gauge was set to 1.299 and inserted in each bore, finding the following clearances:

                        1                   2                   3                   4                 5
-------------------------------------------------------------------------------------
CLEARANCES     .0014              .0011             .0011             .0012            .0016
WITH BROWN
BEARINGS


SO... now, i need help deciphering the best way to get proper clearances. if the brown is the thickest available bearing in the "A" category, can i use the black bearing from the "B" category to reduce clearance? if so, am i best just trying to even the numbers out rather than going black on all of them just to still be seeing a .0005 variable between bearings? if it means anything, the 550 cases ran green bearings.

if it were all numbers here i think i could figure this out, but the lack of actual specs on the bearings themselves confuses me.  help?

[HondaMan]

From the numbers you have, on assembled bearings, it appears you're in the ballpark.

Honda's clearance specs were .0008" to .0012" for new (.001" nominal), with a service limit at .0032". The bearing "clearance" from their stated charts is supposed to be based on "0", which corresponds to the nominal 0.001" clearance. If you have, for example, a .0022" physical clearance in the journal-bearing assembly, then according to Honda's method you have a [.0022" - .001" = +.0012"] "extra" clearance, which is supposed to be "0" clearance.  So, when you select a bearing from their charts, you're looking for a "0" leftover, which is an "invisible" .001". Which they accept as being .0008" to .0012".

After that's been digested.....

The "colors" of the bearing shells refer to the thickness of the shell material itself. Nominal is 1.5mm (0.05905"), but the length of the "crush zone" is varied slightly in manufacture, to make the seated bearing come out pretty close to [the ID desired + .001"], if at least close to round....

One of the things that's neglected in Honda's manuals (and I only gleaned it from a Yosh rep) was the .01mm extra case-to-case clearance "spec" for the Hondabond-like goo between the cases. What he told me, in 1973, was that Honda used 0.01mm shims between the cases to represent this clearance, then bored the cases. (This came up when my friend Jim "Chambo" Chamberlain align-bored his 130,000 mile K0 cases for his first rebuild...).

If you add the "missing" .01mm (.0004") to your case bore dimensions, things look just about right :(1.4171 + .0004) = 1.4175, for example. So, if you take:

1.4175" - (.05905" * 2) = 1.2994", and, in this instance, deduct the .0004" for goo you didn't have when you measured the cases, becomes 1.2990", just like the journals. That's the "0" number, which is supposed to leave you with "standard" clearance of .001".

The BLACK bearings will take you down .0004" on the ID size, from your present clearances, it appears. If I were doing it (like I'm about to do to my 750, next time it's apart), I'd use the BLACK at your #1 and #5, and leave the rest at the BROWN where you have them. And, break the engine in under 5000 RPM for the first 1000 miles. The outer 2 bearings on all of these engines suffer the most from torsional harmonics, making their bearings wear more. On CB750, for some reason, rod #3 often follows the same wear pattern as the crank's ends, never figured out why. 

I don't know if I've explained it very well, but this all has to do with Japanese manufacturing techniques. They all seem to accept the "tolerance" of their fitups, or processes, or whatever, as the "0" or "target" value. Then, they only speak in terms of controlling their "deviances", which are those numbers outside of the "normal" tolerances. It's a little different way of looking at the world, but once you get used to it, it's not so strange. Just don't rebuild an American engine with the Japanese tolerances....you might need some really good oil to make it turn, if you did....

[mystic_1]

Holy crap.


I'm going to start saving every post you ever make like this, HondaMan.

Seriously.


<runs off to create "Hondaman" folder>


mystic_1

[paulages]

well mark- i'm gonna have to read back through that about 5 times to really understand all of what you are saying, but you did make me feel better about my thinking i could run black bearings on the outer two to bring them all close to each other. i swear, i can probably still remember calculus from high school, but decimals still throw me off sometimes...

one thing: i did wonder about the effect hondabond (or 1194 or whatever) would have on those clearances... but i'm a little confused about how it does affect it. wouldn't the extra .0004" increase the diameter of the housing bore and thereby also increase the clearance between it and the journal? going back to read your post again now... maybe it'll make more sense the second time around.

[paulages]

oh yeah, and now i have to try and find black bearings... none at service honda or DSS. i'll try WHH in the morning.

[bryanj]

Paul, sorry nobody i know can be accurate enough with hand held measuring tools! Honda used air gauges where a ground plug or collar is fed with air and the pressure drop gives an exaxt correlation to size.

Plastigauge used right is the only way to go in normal workshop conditions---you just have to ensure NOTHING rotates

[paulages]

Paul, sorry nobody i know can be accurate enough with hand held measuring tools! Honda used air gauges where a ground plug or collar is fed with air and the pressure drop gives an exact correlation to size.

Plastigauge used right is the only way to go in normal workshop conditions---you just have to ensure NOTHING rotates

thanks, bryan. i was watching as he measured and the dial sure seemed pretty accurate. but i sure don't know better. i think i referred to the tool correctly...it was basically a dial bore gauge, where you set it to your smallest ID, and the dial measures the runout from there. since my crank journals were all at 1.299 (minus the one), we set it at that, then measured the ID of the bores with the bearings installed. there was a slight variance throughout the bearing, but only .0001-.0002."  i felt better about it than anything else we did. the honda manual shows measuring the ID of the case bore with a similar bore gauge. i did plastigauge (with nothing moved), but the readings on the strips are so crude, i didn't find myself in any better position. i took pictures of the readings, but they ended up too blurry to post.

oh well, i ordered 6 brown and 4 black from service honda last night-- the black ones and the trans bearings i couldn't find before turned up in my basket...whether or not they actually have them is to be seen, but in the past i would get a notice on the screen telling me the part was unavailable. everything else i need to put this thing together is in that order, so i can't wait...

[paulages]

ok- finally closed this chapter, as all bearings finally came in and i had time to install them. after plastigaging, all clearances were at .0004."

i thought this seemed a little tight, since honda specifies .0008"-.0019" as ideal, but when i factored in the .0005" extra clearance from the 1104 sealer, it looks perfect (.0009").

for what it's worth, i calculated the .0005" as follows:

-housing bore diameter without "goo"= 1.4171".
-this would make it's radius .70855"
-if C=pi(r), then the circumference of the bore would is 2.2248"
-if you add in the .01mm (.0004") hondaman specified for the "goo", then you add .0008" to the circumference.
-working the C=pi(r)2 formula backwards (2.2248=3.14(r), we find a new diameter of 1.41758
-1.41758 (with goo) minus 1.4171 (without goo)= .00048"

so since i plastigaged without the 1104, i can assume the clearances will be .0005" greater than they measured.

[bryanj]

To be honest mate i always re-build with a full set of black shells throughout and run in carefully for a couple of thousand with oil changes every 500. Honda seemed to be precise in clearances so that the motor had the clearances of an already run in motor and just needed "bedding in" before thrashing. I do know Kawasaki had a problem with Z1000 being run too carefully and burning oil---reconned they needed thrashing from new

[paulages]

To be honest mate i always re-build with a full set of black shells throughout and run in carefully for a couple of thousand with oil changes every 500. Honda seemed to be precise in clearances so that the motor had the clearances of an already run in motor and just needed "bedding in" before thrashing. I do know Kawasaki had a problem with Z1000 being run too carefully and burning oil---reconned they needed thrashing from new

well that's good to know, but i've only got black on the outer two. brown on the rest, and it sure feels tight to turn by hand...bear in mind the bearings took assembly lube rather than oil and the NOS bearings on the primary shaft were packed with some pretty thick grease, but it still feels like a tight fit.

[MRieck]

ok- finally closed this chapter, as all bearings finally came in and i had time to install them. after plastigaging, all clearances were at .0004."

i thought this seemed a little tight, since honda specifies .0008"-.0019" as ideal, but when i factored in the .0005" extra clearance from the 1104 sealer, it looks perfect (.0009").

for what it's worth, i calculated the .0005" as follows:

-housing bore diameter without "goo"= 1.4171".
-this would make it's radius .70855"
-if C=pi(r), then the circumference of the bore would is 2.2248"
-if you add in the .01mm (.0004") hondaman specified for the "goo", then you add .0008" to the circumference.
-working the C=pi(r)2 formula backwards (2.2248=3.14(r), we find a new diameter of 1.41758
-1.41758 (with goo) minus 1.4171 (without goo)= .00048"

so since i plastigaged without the 1104, i can assume the clearances will be .0005" greater than they measured.

.0004 is tight. It will take a long time to break the engine in and you will see bearing material in the oil for a while too. I've always shot for the loose end of the spectrum generally using green bearings. Carrillo's like about .002 clearance.

[paulages]

ok- finally closed this chapter, as all bearings finally came in and i had time to install them. after plastigaging, all clearances were at .0004."

i thought this seemed a little tight, since honda specifies .0008"-.0019" as ideal, but when i factored in the .0005" extra clearance from the 1104 sealer, it looks perfect (.0009").

for what it's worth, i calculated the .0005" as follows:

-housing bore diameter without "goo"= 1.4171".
-this would make it's radius .70855"
-if C=pi(r), then the circumference of the bore would is 2.2248"
-if you add in the .01mm (.0004") hondaman specified for the "goo", then you add .0008" to the circumference.
-working the C=pi(r)2 formula backwards (2.2248=3.14(r), we find a new diameter of 1.41758
-1.41758 (with goo) minus 1.4171 (without goo)= .00048"

so since i plastigaged without the 1104, i can assume the clearances will be .0005" greater than they measured.

.0004 is tight. It will take a long time to break the engine in and you will see bearing material in the oil for a while too. I've always shot for the loose end of the spectrum generally using green bearings. Carrillo's like about .002 clearance.

yeah, it is tight. the rods feel good, but the crank bearings definitely feel a little tight. if it's sitting still, it takes both hands on the stator to start it turning. once it breaks, it'll spin freely with one hand. there is likely a little drag from the grease honda used to pack the ball bearings on the ends of the primary shaft (i did oil them to loosen them up a little), but this feels a bit much.

what would you guys recommend? i'll definitely pull it apart and re-plastigage it. i may have used the wrong color. better to have tight but even clearances? or is this likely way too tight and i risk sticking the bottom end? i've never replaced all of the bearings at once having measured for the tight end of hondas clearance specs. maybe a little drag is normal before break-in?

[HondaMan]

A little drag on new bearings is normal, I remember. You might try plastigage on more than one spot to see how round the journals aren't (pretty common after lots of miles).

If you think the rods might be the culprits, and they were too tight, but not round, you can also have the rods' big ends honed round again.

What colors of bearings did you end up with, and are they the same as the 750? (I'm about to rebuild 3 engines...).

[paulages]

A little drag on new bearings is normal, I remember. You might try plastigage on more than one spot to see how round the journals aren't (pretty common after lots of miles).

If you think the rods might be the culprits, and they were too tight, but not round, you can also have the rods' big ends honed round again.

What colors of bearings did you end up with, and are they the same as the 750? (I'm about to rebuild 3 engines...).

i went to my shop, and in an attempt to locate the offending bearings, detorqued and retorqued the cam bolts. the outer two are definitely tighter than the inner three, but upon retorquing all of them, the problem went away. there is still a little bit of stickiness until you initially break the inertia, but you can easily spin it with one hand now.

to answer your question though mark, the inner three sets are brown and the outer two are black. they all were brown upon disassembly, so the outer ones obviously wore a little bit.

[bryanj]

Using assembly lube (basically grease) rather than oil will make for initial "sticktion" but as long as it turns easy after initial all will be OK

[paulages]

Using assembly lube (basically grease) rather than oil will make for initial "sticktion" but as long as it turns easy after initial all will be OK

that was my initial suspect actually, but i've assembled engines with the same lube before without the same stickiness... but they were always within specs but not at the lower end of them like these.

[bryanj]

Paul, as you are going to open up again anyway check the shells for "drag" marks which i dont think you will find as you say it spins easy after initial start, Buid it and fire it but let it run a reasonable time to circulate and heat the oil-----most damage to new engines is done on first start up by keep starting and stopping.

Camshafts in cages need to be run at 2,000 rpm for minimum 5 minutes or the hardening is compromised according to Vauxhall (GM) over here

[paulages]

Paul, as you are going to open up again anyway check the shells for "drag" marks which i dont think you will find as you say it spins easy after initial start, Buid it and fire it but let it run a reasonable time to circulate and heat the oil-----most damage to new engines is done on first start up by keep starting and stopping.

Camshafts in cages need to be run at 2,000 rpm for minimum 5 minutes or the hardening is compromised according to Vauxhall (GM) over here

thanks bryan. i'm not gonna resplit them now after all, at least not unless i run it and feel the need to take it back apart soon. i'll certainly heed your advice about the first warm-up. i usually run it about that long to warm it up, let it cool off, check oil, then run it 20 min or so upon next start up. i've always understood the worst thing you can do for the rings seating is to not let it warm up and not run it in normally for the first 20 miles or so.

[HondaMan]

Paul, as you are going to open up again anyway check the shells for "drag" marks which i dont think you will find as you say it spins easy after initial start, Buid it and fire it but let it run a reasonable time to circulate and heat the oil-----most damage to new engines is done on first start up by keep starting and stopping.

Camshafts in cages need to be run at 2,000 rpm for minimum 5 minutes or the hardening is compromised according to Vauxhall (GM) over here

thanks bryan. i'm not gonna resplit them now after all, at least not unless i run it and feel the need to take it back apart soon. i'll certainly heed your advice about the first warm-up. i usually run it about that long to warm it up, let it cool off, check oil, then run it 20 min or so upon next start up. i've always understood the worst thing you can do for the rings seating is to not let it warm up and not run it in normally for the first 20 miles or so.

Paulages:
I completely forgot this old "trick", remembering it while I was FedExing a package of Honda parts today...try this with sticky bearing reassemblies (I learned it from V8 engines):

Tap on the ends of the crankshaft with a good-sized hammer (plastic head type, or use a wood block on the alternator side, and a long tube on the points side, to protect the end of that side). The intent here is to slide the crankshaft to both sides, several times, then try to settle it in the middle. Reason: there is always "end play" in these (and all) crankshaft assemblies, and this slack can be used to finally align the bearings before the engine is run-in. The original run-in will eventually do this, but racers of old needed to "set" the bearings before the first lap, so we did it this way, instead. The bearings do not set perfectly square when they are crushed into place during the intial torquing sequence. Using the cranksahft slack (and ends of its journals) to nudge the edges of the now-malleable bearings into square will save the burninshing off of those high edges that are making it drag now. You'll probably find the stiffness drops, too.

Sorry, my brain isn't what it used to be in the hard-drive-seek-speed categories.. 

[paulages]

Paul, as you are going to open up again anyway check the shells for "drag" marks which i dont think you will find as you say it spins easy after initial start, Buid it and fire it but let it run a reasonable time to circulate and heat the oil-----most damage to new engines is done on first start up by keep starting and stopping.

Camshafts in cages need to be run at 2,000 rpm for minimum 5 minutes or the hardening is compromised according to Vauxhall (GM) over here

thanks bryan. i'm not gonna resplit them now after all, at least not unless i run it and feel the need to take it back apart soon. i'll certainly heed your advice about the first warm-up. i usually run it about that long to warm it up, let it cool off, check oil, then run it 20 min or so upon next start up. i've always understood the worst thing you can do for the rings seating is to not let it warm up and not run it in normally for the first 20 miles or so.

Paulages:
I completely forgot this old "trick", remembering it while I was FedExing a package of Honda parts today...try this with sticky bearing reassemblies (I learned it from V8 engines):

Tap on the ends of the crankshaft with a good-sized hammer (plastic head type, or use a wood block on the alternator side, and a long tube on the points side, to protect the end of that side). The intent here is to slide the crankshaft to both sides, several times, then try to settle it in the middle. Reason: there is always "end play" in these (and all) crankshaft assemblies, and this slack can be used to finally align the bearings before the engine is run-in. The original run-in will eventually do this, but racers of old needed to "set" the bearings before the first lap, so we did it this way, instead. The bearings do not set perfectly square when they are crushed into place during the intial torquing sequence. Using the cranksahft slack (and ends of its journals) to nudge the edges of the now-malleable bearings into square will save the burninshing off of those high edges that are making it drag now. You'll probably find the stiffness drops, too.

Sorry, my brain isn't what it used to be in the hard-drive-seek-speed categories.. 

sounds like good advice as usual, mark. i'll give it a try. you know, after retorquing and having an easier time turning, i suspected that either the bearings might not have been "set" yet where they'll actually end up, or that they hadn't properly crushed to round yet. the latter really makes sense if they are indeed intended to crush a bit on the ends to form round. a few thousands -or tenths even- clearance would easily be affected by such slight inconsistencies, i'd imagine.