Rod and Main bearings

[JCTracker]

I'm reading in the FSM about how the crank has different sized bores and journals.................

1. Ensure main bearing caps are numbered for location and arrow on cap points toward timing belt end of
crankshaft.
2. Cylinder block main bearing bore size is indicated by a letter "A", "B" or "C" stamped on cylinder
block. See Fig 9. Ensure main bearing bore is within specification. See MAIN BEARING BORE
SPECIFICATIONS table.
3. Crankshaft main bearing journal size is indicated by numerical size mark located on crankshaft
counterweight end. See Fig 10. Ensure main bearing journal is within specification. See MAIN
BEARING JOURNAL DIAMETER SPECIFICATIONS table.
4. If main bearing journal and main bearing bore are within specification, replace main bearings with
original size grade (color code). If color code on original bearing cannot be obtained, use size mark
letter on cylinder block and number on crankshaft to determine proper size main bearing to be used.
See MAIN BEARING SELECTION (STANDARD BEARINGS) table. Standard bearing thickness is
as listed. See BEARING THICKNESS SPECIFICATIONS table.
5. Main bearings are available in .010" (.25 mm) undersize. Undersize bearings are coded with 2 color
code marks. See Fig 11 and Fig 12 . Undersize bearings


If I'm reading all of this correctly it sounds similar to the "gang boring" done to the cylinders in that all of the crank journals are not necessarily the same size and each needs a bearing that matches whatever size the each of the journals actually are. Is this because the inside diameter of each of the cranks 5 bores in the block could be different? Were the blocks not line bored by the factory so that all 5 bores are in line and the same size?  

Here's my question, if I have my machine shop grind and polish the crank .010 do I also need to get the block line bored so all of the bores are the same size and will work with aftermarket .010 undersized bearings or do I need to find these color coded bearings that are specific to each of the 3 possible crank bores?

[fixkick]

I'm reading in the FSM about how the crank has different sized bores and journals.................

1. Ensure main bearing caps are numbered for location and arrow on cap points toward timing belt end of
crankshaft.
2. Cylinder block main bearing bore size is indicated by a letter "A", "B" or "C" stamped on cylinder
block. See Fig 9. Ensure main bearing bore is within specification. See MAIN BEARING BORE
SPECIFICATIONS table.
3. Crankshaft main bearing journal size is indicated by numerical size mark located on crankshaft
counterweight end. See Fig 10. Ensure main bearing journal is within specification. See MAIN
BEARING JOURNAL DIAMETER SPECIFICATIONS table.
4. If main bearing journal and main bearing bore are within specification, replace main bearings with
original size grade (color code). If color code on original bearing cannot be obtained, use size mark
letter on cylinder block and number on crankshaft to determine proper size main bearing to be used.
See MAIN BEARING SELECTION (STANDARD BEARINGS) table. Standard bearing thickness is
as listed. See BEARING THICKNESS SPECIFICATIONS table.
5. Main bearings are available in .010" (.25 mm) undersize. Undersize bearings are coded with 2 color
code marks. See Fig 11 and Fig 12 . Undersize bearings


If I'm reading all of this correctly it sounds similar to the "gang boring" done to the cylinders in that all of the crank journals are not necessarily the same size and each needs a bearing that matches whatever size the each of the journals actually are. Is this because the inside diameter of each of the cranks 5 bores in the block could be different? Were the blocks not line bored by the factory so that all 5 bores are in line and the same size?  

Here's my question, if I have my machine shop grind and polish the crank .010 do I also need to get the block line bored so all of the bores are the same size and will work with aftermarket .010 undersized bearings or do I need to find these color coded bearings that are specific to each of the 3 possible crank bores?

that is correct it was gang bored in the factory and same with cranks done ganged and is very crude this. 1989 is long ago. there are old videos of this and super scary to watch.

gang bored means 4 cutters, all with different wear,  and not the same, it is fast cheap way, and suzuki is all about cheap production costs. and machines.

after market (go to any usa machine shop and watch for 1 hour) I spent half a day here watching my block and crank getting machined ,last time.  
the guy on my crank used the calipers like 5 or more times as he did that, to my crank then use mirco polished journal  tools.  amazing perfect sized at the end . $5 extra charge micro.
real shop:
the cranks and bores of blocks are bore then precision honed by humans 1 by1  bore or journal. never ganged.
that means new after market bearings fit, (ring and pistons too) that do not have this huge list of wild odd sizes, as OEM did.

all machine shops know that.
they mic it all and tell you , see this is a stock engine with queer parts. ; we cure that now.
gone now. (this is not japan nor is it OEM suzuki it is a real USA machine shop) after mic, is done that order hot standard oversized parts, due top knowing at this instant what they will end up at next, do to their skills and a mic.
and real parts with normal perfect sized parts fitted.  (or racing set  losers)
They do a fantastic job of it.

good luck machining.

[fixkick]

what is precision stock is bearing outer bearing shell bores and rod end outer bore sizes (bearings not present) and is checked to , for sure if a bearing was ever spun.
a shop checks all that. never guess. (inside mic)

and cam bores , align bored. (ours have no fitted bearings)
if not true this, omg the bearing crush factors are FAIL. fail hard.
some things must be near prefect, and this is it. (and is spec'd in the manual this, and very little error allowed)

the bearing inside diameter is based on crush factor that never changes. ever.
that is why I do both ways on bearings, mic'd (micrometer) both, then at full torque plastic gauge'd if fails I know for sure I messed up. I take all mic readings and do the math to compute bearing clearances, then later plastigauge tells me I AM NOT WRONG.
to be sure I trust nothing and prove all, that is possible.

[JCTracker]

thanks for the info but I'm not sure I followed everything. Does the American machine shop that I take my block to need to align bore the main bores of the block?

Main bores = Block plus Main Caps (torqued) minus Bearings ?

[JCTracker]

Yes or No please on whether line boring is necessary for a BABAB block before putting a crank ground .010 in with a matching set of .010 oversized main bearings?

[fixkick]

Yes or No please on whether line boring is necessary for a BABAB block before putting a crank ground .010 in with a matching set of .010 oversized main bearings?

you  ask great questions  ( there is no answer, I can not touch your engine or measure parts)
but.,,,, here are some facts.:
and the topic is complex on how suzuki made those engines, gang bore cyclinders, and crank,  rods and main bores are precision ground  in the factory.  in inline mains bored and cam tool.
The unknowns are this. short.
the machine shop MIC's  the top deck is not warped, if is , it is milled. (head too but off topic, this is short block)
then checks all inline bores in mains, to be sure those are not off, too, like any overheated engine can do. same with head in spades (runs hottest it)

The big ends of rods, are precision bored in the factory that means only 1 variable here, and lots of color codes for gang ground crank journals.
That means if suzuki did not precision grind rod ends they would have 3 colors for bore and 3 for crank side, a total of 9 colors. ouch
so they did not , only 3 colors for each size, bearings,  std , and 3 sizes 'over" times 3 colors.
yes complex and crazy this but that is what the factory did, then 30 years later if lucky ran that long

comes rebuild the engine using modern ways and only 3 bearing shells over under sized. for std, and all under sized bearing sold here. super simple this,
the man stands there mics the crank , makes sure it is not bent, (run out) or cracked. and if too much rejects the crank right out, then he says ok, and finds the worst journal on the crank
he then send out a runner (shops have buyer-runners.) buys the bearing that then new ground crank, oversized bearing shells.  (this is never done ever before the grind or tempers flare)

let him decide this, let  the shop measure it and decide , after a journal can be out of round and scored bad and need more grinding and it is HIS CALL on this.

the block is a whole other matter, same story really lots of measuring for wear, out of round bores on all points, all bearings and cylinders.
then they talk to you.,  with good news or bad,  this job measuring takes and hour or more,  for sure checking for out of round and bores not inline.
old engines need very very careful measuring or run the risk spending big cash on a block no good. or crank/rod bad. a horror max.
pressure testing the block and head too.
metal checks for cracks.

the other factor is what parts are sold, some popular engines on can by bearings just journal sized right but for bored out inline MAIN CAPS.  2 AXIS  RULES.
The gets the crush spec right,  all bearing crush, with main caps torqued to spec, that is how they work and land on perfect clearance.
Usually the bearing bores, rod and mains are good, and not out of line,  so the crush will  be at spec,.
and then only 3 or so sizes of bearing sold and needed, 10 over or what ever is need to get what is called cleanup. (after grind it is clean surface so the then micro polish it last (crank)
even honda for years micro polished cylinders and no engine break-in needed at all , and not burn oil in the the cat lower its life early.

step one is the block
it must be good and not out of line ,cracked and not worn behind the largest size bearing sold (or pistons)
then rods good, not bent or bores wrecked or cracked
and last the crank, is tested fully, for cracks or  bent and then measured all journals for out of round or then he calls you and says 10 over will be a go.
that is how it is done  most shops (machine) do all this while you sleep or work.
some shops post a list of steps done like 100,. checks.   they know what to do, and tell you at every step if a part you had can not be rebuilt. super common on old engines.
cracks happen, or warping, for sure overheated engine, or run water for coolant and ICE FROZE cracked the block and head where you can not see.

the crank and block must be measured, extensively before any grinding or last bearings bought.
there are engine rebuild books in print that are super good to read, for sure on topic rebuilding racing engines.
ever bit of this is in print, and more... like balancing etc.

good luck with your build,  it can be done 1 step at a time, and the block is first (head already done)

study how line bores are measured. if it is not inline the mains the engine are doomed.
it will cause the bearing to not be free, at all, and hand turning the crank , no pistons can not be done it is stuck.
same with bent crank
or bent rods
no bent , no cracks no warps.

[fixkick]

yes crank and block , not warped. the answer is yes, but is super simplistic to say. that.
the crank not bent, and block mains not warped out of line, as is so common.
this engine goes to 6000 RPM so there is very little forgiveness, here.

there are very special tools in the machine shop to measure all this easy.
some even do it for low cost, if asked, hand them block and crank, and rods and they check it all for a fee. (and cylinder bores checked) and lots more. (it has great value all this)
that beats the hell out of failure. in the end.
sure does. IMO

those codes on the crank end and top block end mean zero now that ended day1 new car long long ago
only what the machinist measures now matters, , and unknown.