Small Engine ReassemblyBriggs & Stratton OHV

A Visual Guide

Objectives:

Reassemble an engine following concise steps and detailed notes taken by the student.

Utilize proper tool techniques. Reinforce lecture-based theoretical discussions. Utilize and reference engine standards with

appropriate engine manuals.

Procedure Notes:

Follow the reassembly steps precisely. Be sure to reference notes and sketches you created

during engine disassembly.

Your engine may not be exactly like the engine in this presentation. Even if your Briggs & Stratton OHV engine is not exactly like the model used in this presentation, many of the procedures will be the same.

Use reassembly grease on all internal parts and follow all specifications!

Pre-Assembly Cleaning

Clean all internal parts in the parts cleaning cabinets. Remove excess solvent with compressed air. Eye protection and chemical

resistant gloves are required.

Step 1: Install the Crankshaft

Reminder: Tapered end to the front of the engine.

Pre-operation grease

Step 2: Reassemble the Piston Rings and Connecting Rod

Reminder: The rings must be replaced correctly. Review your sketch of connecting rod and piston ring

orientation.

Step 2: Reassemble the Piston Rings and Connecting Rod

Connecting rod & piston orientation. Arrow on piston and MAG abbreviation to the

magneto side of the engine.

wrist pin clips

Step 3: Install the Piston and Connecting Rod in the Cylinder

Reminder: Clean and coat cylinder wall with lubricant. Use piston ring compressor. Install in the correct orientation.

Step 3: Install the Piston and Connecting Rod in the Cylinder

Use your thumbs or the handle of a mallet to

gently insert the piston assembly.

Rotate the crankshaft to prevent it from striking the connecting

rod during reassembly.

Step 4: Replace Connecting Rod Cap

Reminder: Lubricate interior of rod cap and connecting rod. Replace cap and rod in the correct direction. Replace oil splash and rod cap lock. Torque

screws properly.

Arrow toward cylinderShort screw and oil splash away from cylinder

Step 5: Replace Tappets

Note: Lubricate each tappet

Step 6: Replace Cam Gear

Reminder: Make sure journal is secure. Line up timing marks. Lubricate all bearing surfaces.

Step 7: Install Crankcase Cover

Reminder: Use correct gasket. Tighten bolts in correct sequence by skipping across the cover. Replace oil seal if needed. Adjust end

play if needed.

Step 8: Install Flywheel

Install flywheel and key.

Install Starter Cup and Nut

Torque flywheel nut using a strap wrench

and ft.lb. torque wrench.

Installing Cylinder Head & Adjusting Overhead Valves

Return to your measurement sheets in Chapter 9 to record your measurements.

Step 9: Insert Valves Into Head

Insert valves from the bottom of the head, while using your

thumbs to lock the valve retainer. Oil seal on intake valve

Exhaust valve guide rises

Step 10: Install the Cylinder Head

Reminder: Install head gasket first. Torque head bolts in a crisscross pattern.

Step 11: Install Pushrods & Valve Wear Plates

Pushrod

Valve Wear Plates

Step 12: Align Rocker Arms with Push Rods & Valve Wear Plates

Reminder: Use the rocker arm as a fulcrum to slightly compress each valve spring in order to slide its opposite end on top of the push rod.

Step 13: Prepare the Cylinder for Valve Adjustment

Reminder: Rotate piston to TDC compression. Use a screwdriver in the sparkplug opening as a guide or align the PTO keyway to the

cylinder. Now rotate the flywheel clockwise until the magnet points straight up. This disengages the compression release on the

camshaft.

Step 14: Check Valve Clearance

Reminder: According to specification, insert a flat feeler gauge between the rocker arm and valve wear

plate. Make adjustments if out of gap tolerance.

Step 15: Adjusting Valve Clearance

1. Insert feeler gauge2. Loosen locking screw, while holding adjustment nut.3. Adjust clearance with the adjustment nut.

4. Hold adjustment nut and lock rocker arm.

Note: Don’t forget gasket. Short bolt to the top.

Step 16: Replace Valve Cover

Step 17: Install Armature

Note: Thread kill wire through port in block. Bolt armature to block. Adjust

armature air gap with shim or business card.

Step 18: Insert Heat Shield

Note: One screw only

Reminder: Refer to your drawings to ensure all linkage is correctly assembled.

CarburetorLinkage

GovernorArm

4 Bolts

Step 19: Replace Linkage Plate

Insert Kill Wire

Step 20: Replace Carburetor

1. Attach spring & linkage to carburetor

2. Insert both gaskets & spacer.

Step 21: Reset Governor (IMPORTANT)(IMPORTANT)

Reminder: Ensure that all linkage travels freely.

Confirm that throttle butterfly is open completelySet throttle to full

Step 21: Reset Governor (IMPORTANT)(IMPORTANT)

Procedure: Use a 1/4” nut driver and 3/8”. Rotate governor shaft counter clockwise until it stops (do not force). Tighten governor arm lock with 3/8” wrench.

Step 22: Insert Spark Plug

Step 23: Replace Blower Housing

Note: Linkage plate flange mounts with the blower housing top. Weave the blower housing over, under, and over.

Step 24: Replace Muffler

Note: Include gasket. #30 star tool required. Replace muffler guard. One bolt at rear of muffler and four screws at front.

Step 25: Replace Fuel Tank

Note: Replace fuel line. Four bolts front and back.

Step 26: Replace Throttle & Fuel Valve Cover Plate

Note: Fuel valve must be in off position. Throttle must be at half.

Step 27: Replace Air Cleaner

Mounting Plate& Gasket Filter & Cover

Steps 28-29: Fill Crankcase with clean oil. Fill fuel tank 1/3 full with gasoline.

Be sure to add gasoline, not any other fuels.

Step 30: Start and Run Engine

Turn run switch “ON” and set throttle to 1/2. No starting fluid should be needed.

Reminder: Only while instructor is present. Use engine stand and vice.

Step 31: Adjust Carburetor & Take Measurements

Temperature Readings

Full Throttle RPM & Carburetor Adjustment

Let engine operate for approx. 5 min.Let engine operate for approx. 5 min.

Step 32: Remove Fuel & Lubricant

Place fuel and lubricant into their appropriate containers.

Reassembly Wrap-Up

Place a piece of tape on your engine that has your name as well as a report of how the engine ran. Return engine to storage area.

Inventory and clean all tools in your assigned box. Clean and return your engine storage bin to its

storage area. Clean and straighten your area.