Bluish circular area in picture

Just a little over 53.3 gallons

To get a circle with a perimeter of 18 inches, you want a diameter of about 5.73 inches (just under 5 3/4 inches) or a radius of 2.86 inches (call it 2 7/8 inches). Get a compass, set its legs 2 and 7/8 inches apart, put one end at the center, and turn.

21 cm is 8-1/4 inches. You could use an 8 inch blade or 7-1/4. But the diameter of the blade is not the critical thing. You must have a correctly fitting hole in the blade to mount on the saw shaft. Standard English size of the hole is 5/8 inch. Just take your saw with you to the store and try a blade on it. If the hole is a nice fit, your are good! (You posted this under circular saws, so I assume your saw is portable.)

no, will never happen. Make yourself a jig, 1/4" plywood set on your table top woth a small brad set 4" from blade. make a tiny hole in board to be cut into circle, spin the board on the brad, and look a wagon wheel.

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)

measure from the center of the shaft to the inside of the guard, double that distance. subtract about 3/4 of an inch and this will be real close to the blade diameter that you need

if you have a Sony LCD projection ..Theres good chance optical block needs replacing .This spot will get bigger and will eventually cover most of screen the longer you use it .needs repair.If there is no warranty on this unit..I would estimate repair around 6- 8 hundred dollars ..

if it's only one cylinder... bad spark plug wire or spark plug would be suspect.... swap the plug wires from another cyclinder... at the coil pack and plug and see if the misfire has "moved"

Robert

http://doitbest.com/Circular+Saw+Blades-Oldham+Saw+Co.-model-538P-doitbest-sku-382647.dib Here you go.

If it's a circular area you might be delaing with magnetism. Check the menu and there should be a control for geomagnetic correction and adjust accordingly.