I am trying to find out if pistons and rings are STD as well as Big end bearings. This is the number stamped on them Big ends (3B55D) Rings (2N) Thanks Sorry for a Toyota 3L Engine 335190

Whenever a motor is taken apart so that you can install piston rings, it is rather common to replace many other parts at that time.
Commonly, all of the replaceable bearings ( crank & cam) are changed.
Also commonly, the engine block is bored so that new pistons can be fitted, because of wear on the cylinder walls.
Commonly, an inside micrometer will tell the technician how much to bore the block.
The block is usually bored from .010 up to .040.
If the block is so bad that a .040 will not be big enough, the block is scrapped out.
Then, "oversized" pistons and rings are fitted to the new size hole.
You would measure the size of the bore to tell which size rings to buy.
God bless your efforts.

Head Gasket
Rocker cover gasket
Inlet & exhaust manifold gaskets
Main and Big end bearings
Service manual Oil filter

the pistons are starting to bond to the cylinder walls
the rings are starting to break up
the oil ( what is left of it) is boiling off
the big ends and main bearings are starting to fail
the cause of the sound is the engine starting to disintegrate

THis job requires a lot of ability and is not a job for beginners. It involves engine out, head off. removal of wear lip at top of cylinders. big ends off , pistons out. Checking ring gap of new rings,checking pistons, assembling rings without breaking them, REplacing pistons,big ends head and gasket. checking cam timing etc. As I said it is not a job for beginners and you will need a lot of expert guidance for the job

It's rare that a piston goes bad. So, you need to determine why it failed.
Most times, the cylinder wall is damaged during a piston failure making it impossible to just replace the piston. Check the wall for score marks and out of round condition as well as actual size VS original bore size. (correcting that requires machine work) The new piston must match the cylinder bore as it is now, NOT what it was when manufactured. (same applies to rings).
The old rod can be re-used if it is not bent and providing that the big end (crank end) is still round. Again, the rod needs to be assembled by a machine shop as the wrist-pin is a press-in part.
Most times, you will find that the amount of actual work necessary to replace one piston exceeds what would be necessary to replace the engine in both time, $ and reliability.
If you want to try a replacement though, see if you can get a piston/rod assembly that is still in good condition from a blown junkyard engine, Plasti-gage the bearing and replace if necessary, clean out the ring grooves or replace the rings. Use a hand held cylinder hone and break the glaze on the cylinder walls. If you are careful and everything goes well, it MIGHT work.
Personally I would never replace pistons in an engine without doing all the necessary machine work though.

G'day. The torque specs for the 8mm head bolts is 18ft/lbs.the jug?(cylinder or barrell) is just tightened down even & firm, as there is no acess for a torque wrench.
OK. other things to note.
Clean the cylinder first in solvent(kero or fuel).Then in warm soapy water in a bucket. Dry-(compressed air is best for this-wear eye protection).once dry lubricate all power valves with oil.
Using a clean white rag-soak the end in your 2 stroke oil & wipe the inside of the cylinder surface untill the rag comes back clean(you will need to do it a couple of times-turn the rag over & do it again).Lube the new piston just before assembly-Also pour a little oil down the main bearing oil holes & over the big end too.
Other things to be sure of are-
Piston on the right way round-arrow to the exhaust.
Rings right way up. Some 2stroke dirtbike rings will only go one way up.Look CLOSELY at the ring ends-on the upper or lower surface there may be an etched dot or "T" or "N" or other marking. the mark goes facing up(on both rings unless single ring piston).
rings positioned with end gaps over the locating pins(the ring grooves have a pin in them to stop the ring turning)
Piston pin clips in correctly.
Powervalve moves freely.
Again-watch when you fit the cylinder-it can be tricky to keep the ring end gaps over the locating pins as you feed the cylinder over the piston.
Hope this all helps
Regards(done this a thousand times)Andrew Porrelli

General Specifications Item Specification
Displacement L (CID) 4.6 (281)
Number of Cylinders 8
Bore and Stroke mm 90.2 x 90.0
Firing Order 1-3-7-2-6-5-4-8
Oil Pressure (HOT @ 1500 rpm) kPa 138-310
Drive Belt Tension a
Cylinder Head and Valve Train
Combustion Chamber Volume cm 52?±.5
Valve Seats Width?€"Intake mm 1.9-2.1
Valve Seats Width?€"Exhaust mm 1.9-2.1
Valve Seats Angle 44.51-45.01 degrees
Valve Seats Runout (T.I.R.) Max mm 0.025
Valve Arrangement (Front-to-Rear) (Left Hand) E-I-E-I-E-I-E-I
(Right Hand)
I-E-I-E-I-E-I-E
Valve Stem to Guide Clearance?€"Intake mm (Inch) 0.020-0.069
(0.00078-0.00272)
Valve Stem to Guide Clearance?€"Exhaust mm (Inch) 0.045-0.095 (0.0018-0.0037)
Valve Head Diameter?€"Intake mm (Inch) 44.5- (1.75)
Valve Head Diameter?€"Exhaust mm (Inch) 34.0 (1.34)
Valve Head Diameter?€"Gauge Diameters mm (Inch) 42.5- and 32.0
(1.67 and 1.26)
Valve Face Runout Limit mm (Inch) 0.05 (0.002)
Valve Face Angle 45.25-45.75 degrees
Valve Stem Diameter (STD)
?€"Intake mm (Inch) 6.995-6.975 (0.275-0.2746)
Valve Stem Diameter (Std)
?€"Exhaust mm (Inch) 6.970-6.949 (0.274-0.2736)
Valve Springs?€"
Compression Pressure N @
Spec. Length?€"Intake 587.14 N @ 28.02 mm
Valve Springs?€"
Compression Pressure N @
Spec. Length?€"Exhaust 587.14 N @
28.02 mm
Valve Springs?€"Free
Length ( Approximate)?€"
Intake mm (Inch) 49.55 (1.951)
Valve Springs?€"Free
Length (Approximate)?€"
Exhaust mm (Inch) 49.55 (1.951)
Valve Springs?€"Installed
Pressure N @ Spec. Length
?€"Intake 244.64 N @ 40.0 mm
Valve Spring?€"Installed
Pressure N @ Spec. Length
?€"Exhaust 244.64 N @ 40.0 mm
Valve Springs?€"Installed
Pressure N @ Spec. Length
?€"Service Limit 10 % Pressure Less @ 28.02 mm
Valve Springs?€"Installed
Pressure N @ Spec. Length
?€"Out of Square Limit 2 degrees
Valve Guide Inner
Diameter mm (Inch) 7.015-7.044 (0.2761-0.2773)
Rocker Arm?€"Ratio 1.75:1
Valve Tappet?€"Diameter
(STD) mm (Inch) 16.000-15.988 (0.66-0.629)
Valve Tappet?€"Clearance
to Bore mm (Inch) 0.018-0.069
(0.00071-0.00272)
Valve Tappet?€"Service
Limit mm (Inch) 0.016 (0.00063)
Valve Tappet?€"Hydraulic
Leakdown Rate b 5-25 seconds
Valve Tappet?€"Collapsed
Valve Tappet Gap?€"
Desired mm (Inch) 0.085-0.45 (0.0033-0.0177)
Camshaft
Lobe Lift?€"Intake
mm (Inch) 6.58939 (0.2594)
Lobe Lift?€"Exhaust
mm (Inch) 6.58939 (0.2594)
Lobe Lift?€"Allowable
Lobe Lift Loss mm (Inch) 0 (0)
Theoretical Valve Lift @
Zero Lash?€"Intake
mm (Inch) 12.0 (0.472)
Theoretical Valve Lift @
Zero Lash?€"Exhaust
mm (Inch) 12.0 (0.472)
End Play mm (Inch) 0.025-0.165
(0.00098-0.0065)
Journal to Bearing
Clearance mm (Inch) 0.025-0.076
(0.00098-0.003
Journal to Bearing
Clearance?€"Service Limit
mm (Inch) 0.021 (0.0048)
Journal Diameter (All)
mm (Inch) 26.962-26.936
(1.061-1.060)
Journal Diameter (All)?€"
Bearing Inside Diameter
(All) mm (Inch) 27.012-26.987
(1.063-1.0625)
Camshaft Runout
mm (Inch) 0.05 (0.002)
Cylinder Bore
Diameter?€"Surface Finish
(RMS) 0.2-0.6 Microns
Diameter?€"Out-of-Round
Limit mm (Inch) 0.015 (0.0006)
Diameter?€"Out-of-Round
Service Limit mm (Inch) 0.020 (0.00079)
Diameter?€"Taper Service
Limit mm (Inch) 0.006 (0.00023)
Piston
Piston?€"Diameter?€"
Coded Red 1 mm (Inch) 90.177-90.197
(3.550-3.551)
Piston?€"Diameter?€"
Coded Blue 2 mm (Inch) 90.190-90.210
(3.5507-3.5515)
Piston?€"Diameter?€"
Coded Yellow 3 mm (Inch) 90.203-90.223
(3.513-3.5521)
Piston-to-Bore-Clearance
mm (Inch) -0.015 + 0.031 (0.0005-0.0012)
Pin Bore Diameter
mm (Inch) 22.0015-22.004
(0.866-0.8663)
Ring Groove Width?€"
Compression (Top)
mm (Inch) 1.520-1.550 (0.06-0.610)
Ring Groove Width?€"
Compression (Bottom)
mm (Inch) 1.520-1.530 (0.060-0.0602)
Ring Groove Width?€"Oil
Ring mm (Inch) 6.996-7.224 (0.275-0.2844)
Piston Pin?€"Length
mm (Inch) 61.93-62.05 (2.44-2.443)
Diameter mm (Inch) 21.994-21.999
(0.866-0.8661)
Pin to Piston Clearance
mm (Inch) 0.005-0.010
(0.0002-0.0004)
Pin to Rod Clearance
mm (Inch) 0.015-0.040
(0.0006-0.00157)
Piston Rings?€"Ring Gap
?€"Compression (Top)
mm (Inch) 1.0 MAX (0.0394)
Piston Rings?€"Ring Gap
?€"Compression (Top)
mm (Inch) 1.0 MAX (0.0394)
Oil Ring?€"Side Clearance
mm (Inch) 1.25 MAX (0.05)
Oil Ring?€"Compression
(Top) mm (Inch) 0.040-0.090
(0.0016-0.0031)
Oil Ring?€"Compression
(Top) mm (Inch) 0.030-0.080
(0.0012-0.00031)
Oil Ring Snug Fit
Oil Ring?€"Service Limit
mm (Inch) 0.015 MAX (0.0006)
Ring Gap?€"Compression
(Top) mm (Inch) 0.23-0.49
(0.01-0.02)
Ring Gap?€"Compression
(Bottom) mm (Inch) 0.23-0.49
(0.01-0.02)
Ring Gap?€"Oil Ring (Steel
Rail) mm (Inch) 0.05-0.66 (0.006-0.026)
Lubrication System
Oil Capacity?€"Automatic
Transmission (Quarts U.S.) 6.675?±0.125
Oil Capacity?€"Manual
Transmission (Quarts U.S.) 6.425?±0.125
Cylinder Block
Main Bearing Bore
Diameter mm (Inch) 72.401-72.422 (2.85-2.851)
Crankshaft and Flywheel
Main Bearing Journal
Diameter mm (Inch) 67.483-67-503 (2.65-2.657)
Connecting Rod Journal?€"
Diameter mm (Inch) 52.988-53.003
(2.0861-2.0867)
Crankshaft Free End Play
mm (Inch) 0.130-0.301 (0.0051-0.012)
Crankshaft Runout to Rear
Face of Block mm (Inch) 0.050 MAX (0.002)
Connecting Rod Bearings
Clearance to Crankshaft?€"
Desired mm (Inch) 0.027-0.069 (0.001-0.0027)
Clearance to Crankshaft?€"
Allowable mm (Inch) 0.027-0/069 (0.001-0.0027)
Bearing Wall Thickness
(STD) mm (Inch) 2.44-2.452 (0.096-0.0965)
Main Bearings
Clearance to Crankshaft?€"
Desired mm (Inch) 0027-0.065
(0.0011-0.0026)
Clearance to Crankshaft?€"
Allowable mm (Inch) 0.027-0.065
(0.0011-0.0026)
Bearing Wall Thickness
(STD) mm (Inch) 1.920-1.928 (0.075-0.076)
Connecting Rod, Piston and Rings
Connecting Rod?€"Piston
Pin Bore Diameter
mm (Inch) 21.959-21.979
(0.864-0.865)
Connecting Rod?€"
Crankshaft Bearing Bore
Diameter mm (Inch) 56.756-56.876 (2.234-2.24)
Connecting Rod?€"Length
(Center-to-Center)
mm (Inch) 150.7 (5.93)
Alignment (Bore-to-Bore
Max. Diff.) c ?€"Twist
mm (Inch) 0.050 per 25 (0.0015-0.984)
Alignment (Bore-to-Bore
Max. Diff.)?€"Bend
mm (Inch) 0.038 per 25 (0.0015-0.984)
Side Clearance (Assembled
to Crank)?€"Standard
mm (Inch) 0.015-0.45 (0.0006-0.0177)
Side Clearance (Assembled
to Crank)?€"Service Limit
mm (Inch) 0.05 MAX (0.02)
Crankshaft Main Bearing
Journal Taper mm (Inch) 0.020 (0.0007)
Crankshaft Main Bearing
Journal Runout mm (Inch) 0.05 (0.002)
Crankshaft Connecting Rod
Journal Taper mm (Inch) 0.015 (0.0006)

both 2 and 4 stroke motor pistons will have and arrow on the piston, this points to the exhaust port,2 strokes have locating pins for the rings and the end of the rings go to these pins,as you will not be able to get back into the barrel if not fitted like this. 4 stroke rings are posistioned at 120 degree intervals to each other so the end gaps dont line up and there will be numbers stamped on the top and scraper rings which you face up.

YOU HAVE TO REMOVE UNIT FROM CAR.REMOVE THE CONTROL VALVE ASSEMBLY AND THE ACTUATING LEVER.REMOVE THE PITMAN ARM SHAFT ASSEMBLY.REMOVE THE CAP SCREWS HOLDING THE UPPER END COVER TO THE HOUSING AND REMOVE THE END COVER.USE A SMALL PUNCH OR SCREWDRIVER TO REMOVE THE OIL SEAL FROM THE COVER BE CAREFUL OF THE NEEDLE BEARING.NOTE THAT IDENTIFICATION NUMBER OF THE BEARING IS INSTALLED TO THE OUTSIDE OF THE COVER.PULL THE RACK PISTON BALL NUT AND THE WORM ASSEMBLY FROM THE HOUSING.REMOVE THE PISTON RINGS FROM THE PISTON REMOVE THE BALL NUT RETAINING SCREW. TURN THE RETAINING SCREW HOLE DOWN SO THAT THE BALLS AND THEIR GUIDE DO NOT DROP OUT AND SLIDE THE BALL NUT AND WORM ASSEMBLY OUT OF THE RACK PISTON.REMOVE THE BALL GUIDE FROM THE NUT AND TURN THE HOLES DOWN.THEN TURN THE WORM BACK AND FORTH UNTIL ALL THE BALLS HAVE BEEN CAUGHT ON A CLEAN CLOTH.THERE ARE 23 BALLS.THEY HAVE A DEFINITE SIZE AND MUST BE REPLACED AS A SET.THEIR SIZE IS STAMPED ON THE END OF THE BALL NUT.REMOVE THE BALL NUT AND ADAPTER FROM THE WORM.REMOVE THE RETAINING RING WASHER AND SEAL.FROM THE NUT SIDE OF THE ADAPTER.CHECK OVER THE BALL RETURN GUIDES AND CLIPS THE RACK PISTON THE BALL NUT AND THE WORM.THE WORM AND BALL NUT ARE A MATCHED ASSEMBLY IF ONE IS DAMAGED BOTH MUST BE REPLACED WITH A NEW SET.DO NOT DISTURB THE END PLUG IN THE RACK PISTON UNLESS IT IS LOOSE.IT CAN BE DRIVEN OUT FROM THE INSIDE OF THE RACK PISTON.STAKE THE NEW ONE IN PLACE AT FOUR POINTS.THE END PLUG IN THE HOUSING IS DRIVEN TO THE OUTSIDE BUT IS INSTALLED FROM THE INSIDE.IT SHOULD ALSO BE STAKED AT FOUR POINTS.

at the library chiltons manual