Briggs & Stratton 124435 User Manual

BRIGGSRACING.com

Not for

Reproduction

BRIGGS&STRATTON

CORPORATION

MS-5702-4/08

POsT OffICe bOx 702

MIlwAukee, wI 53201 usA

414 259 5333

©2008 Briggs & Stratton Corporation

Version 4/08

Not for

Reproduction

Racing Performance Catalog & Reference Guide

Model/Type: 124435 8105-01

TABLE OF CONTENTS

Not for

Reproduction

SAFETY .................................................................................................1

WORLD FORMULA

General Specs ......................................................................................3

Special Tools .........................................................................................3

Torque Specs ........................................................................................3

Racing Specifics ...................................................................................3

Optional Performance Parts ................................................................3

Highlighted Features ............................................................................3

Cylinder Assembly Parts Explode ........................................................4

Head Assembly Parts Explode .............................................................5

Housing & Flywheel Parts Explode ......................................................6

Carburetor Assembly Parts Explode ....................................................7

Clutch Assembly Parts Explode ...........................................................8

Starter Assembly Parts Explode ..........................................................9

Control Bracket & Gasket Sets Parts Explode ................................ 10

PZ26 Carburetor Tuning Guide ......................................................... 11

Electric Starting System Wiring Diagram ........................................ 12

SAFETY

Not for

Reproduction

SAFETY

1

SAFETY

Not for

Reproduction

BRIGGS & STRATTON DOES NOT APPROVE OR AUTHORIZE THE USE OF THESE ENGINES ON 3 WHEEL ALL TERRAIN VEHICLES (ATVS), MOTOR BIKES, FUN/RECREATIONAL GO-KARTS, OR
AIRCRAFT PRODUCTS. USE OF THESE ENGINES IN SUCH APPLICATIONS COULD RESULT IN PROPERTY DAMAGE, SERIOUS INJURY (INCLUDING PARALYSIS), OR EVEN DEATH. THIS ENGINE
REQUIRES SPECIAL TECHNICAL EXPERTISE AND PREPARATION BEFORE IT CAN BE USED IN COMPETITIVE EVENTS.

2

WORLD FORMULA

Not for

Reproduction

GENERAL SPECS

Model: 124335
Type: 8105
Displacement: 12.48 Cu. in.

- 206 cc
Design: Slant, 30 degree,
Overhead Valve, Electric Start
Bore: 2.6875/2.6885 in.
Stroke: 2.2 in.
Compression Ratio: 9.5 to 1
Factory Timing: 29 degrees BTDC

SPECIAL TOOL REQUIREMENTS

General Model 12 Manual Part No. 272147
PVL Flywheel Puller Part No. 19584
Flywheel Wrench Part No. 19433

TORQUE SPECS

Description Wrench/socket size torque

Air Guard 7mm 40-50 lb-in. (4.5-5.6 Nm)
Blower Housing 10mm & 3/8" 60-110 lb-in. (7-12.5 Nm)
Carburetor (to manifold) 10mm 80-110 lb-in. (9-12.4 Nm)
Connecting Rod T27 140-150 lb-in. (16-17 Nm)
Cylinder Head Bolts 10mm 200-220 lb-in. (20-27 Nm)
Exhaust Brace Screws 10mm 95-125 lb-in. (11-14 Nm)
Exhaust Stud 10mm 95-125 lb-in. (11-14 Nm)
Flywheel Nut 15/16 55-75 ft-lbs. (74.5-101 Nm)
Flywheel Fan 10mm 180-240 lb-in. (20-27 Nm)
Intake (to cylinder) 5mm Allen 70-90 lb-in. (8-10.2 Nm)
Oil Drain Plug 3/8" 100-125 lb-in. (11-14 Nm)
PVL Module 7mm 20-35 lb-in. (2.3-4 Nm)
Rocker Arm Stud 7/16" 90-120 lb-in. (10-14 Nm)
Rocker Arm Plate 10mm 70-90 lb-in. (7.9-10.1 Nm)
Rocker Arm Set Screw 1/8" Allen 50-70 lb-in (5.6-7.9 Nm)
Spark Plug 5/8" Deep 95-145 lb-in. (11-16.4 Nm)
SIde Cover 10mm 95-125 lb-in. (11-14 Nm)
Starter Gear #2 Phillips 35-53 lb-in. (4-6 Nm)
Top Control Plate 10mm 70-90 lb-in. (8-10 Nm)
Valve Cover 10mm Lower & 3/8" 30-60 lb-in. (3.5-7 Nm)

RACING SPECIFICS

PVL™ Ignition Module Gap - .010/.014 (.15/.36mm)
Digital Rev Limiter - 7,000 RPM +/- 50
Spark Plug - Champion™ RG4HC
Fuel Requirements - 98 Octane (RON)
Recommended Oil Capacity - 16 oz., High Grade 30 Weight
(Even for initial break-in)
Exhaust System Requirements-50mm x 57mm Flex Coupling,
50/90 Canister Muffler.
Starter System-12 Volts @ 20 Amp Capacity-180 Cold Cranking
amps. Refer to your sanctioning body rules for required
installation location.

OPTIONAL PERFORMANCE PARTS

High - G/Force Breather Bypass System - Part No. 555688

Installing Cylinder Head Plate

Torque to 90 - 120 in-lbs.
(10 - 14 Nm)

Torque to
70 - 90 in-lbs.
(7.9 - 10.1 Nm)

Adjusting Valve Clearance

WORLD FORMULA ENGINES

Torque to 50 - 70 in-lbs.
(6 - 8 Nm)

Feeler Gauge

HIGHLIGHTED FEATURES

· Dual Ball-Bearing, RACING Reinforced Cylinder

· Billet Rod

· Slotted, Stelite-Faced, Ground Cam w/ Compression Release

· Dual, High-Silicon Valve Springs

· PVL™ Digital Ignition System w/7,100 RPM Limiter

· CNC D-Shape Intake Port

· Walbro™ Round -Slide Carburetor

· Dana™ Fire-Ring Head Gasket

· Racing Crankshaft w/ Induction-Hardened Crankpin

· Green™ Air Filter

· Federal Mogul™ Moly-Coated Cam Ground, Barrel-Faced Piston

· Chrome-Faced, Racing Only Ring Package

· Port-Liner, Exhaust System

· Mikuni™ Fuel Pump

· Noram™ Clutch w/ Quick Change Sprocket Set

· Automotive 3-Piece Valve Retainer System

· Beefy Rocker Arm Stud Nuts

3

WORLD FORMULA cylinder assembly

Not for

Reproduction

(Engine Model Series 124335)

WORLD FORMULA ENGINES

272147 Repair Manual

555688 Breather Assembly

(Optional, Also includes 691890 Rocker Cover Gasket)

699485 Crankcase Gasket•

691664 Screw

(Connecting Rod)

555680 Cylinder Shield

699483 Metric Screw

(Cylinder Shield)

557135 Crankshaft

557117 Connecting Rod

557121 Piston Assembly

(Std., with File to t Top Ring)

557122 Piston Assembly

(.10" Over, with File to t Top Ring)

557123 Piston Assembly

(.20" Over, with File to t Top Ring)

557124 Piston Assembly

(.30" Over, with File to t Top Ring)

555664 Ring Set

(Std.)

555665 Ring Set

(.10" Over)

555666 Ring Set

(.20" Over)

555667 Ring Set

(.30" Over)

555140 Bushing/Seal Kit

692600 Breather Tube

55513 Ring Set

(.10" Over - Contains 10 Top Rings)

55514 Ring Set

(.20" Over - Contains 10 Top Rings)

55515 Ring Set

(.30" Over - Contains 10 Top Rings)

699359 Flywheel Nut†

299819s Oil Seal

(Magneto Side)

695087 Timing Gear†

692517 Bearing•

281658 Oil Fill Cap•

281568 Plug•

555652 Crankshaft Endplay Shim

(Contains .007, .012, .018, & .025)

281658s Oil Fill Cap•

692550 Oil Seal•

(PTO Side)

699478 Screw

(Crankcase Cover/Sump)

Briggs & Stratton Racing Oil (

was specically co-developed and veried to offer superior

protection and performance in our racing engines. It is the only oil

recommended and proven for use in our racing engines.

555630 Crankcase Cover

part #100104

) by Valvoline

222698S Oil Drain Plug*
691663 Oil Drain Plug

(Magnetic, Optional)

555687 Cylinder Assembly

555579 Locating Pin*

698024 Ball Bearing†

691686 Flywheel Key

557117 Connecting Rod

499423 Piston Pin

691866 Piston Pin Lock

690979 Woodruff Key†

557041 Camshaft

*Included with 555687 Cylinder Assembly

(Includes all parts shown)

Included with Respective Piston Assembly

(Includes all parts shown)

† Included with 557135 Crankshaft

Included with 555520 Piston Pin

• Included with 555630 Crankcase Cover

4

WORLD FORMULA head assembly

Not for

Reproduction

(Engine Model Series 124335)

692557 Hex Washer Head Screw

(Rocker Cover Top & Sides)

699481 Hex Washer Head Metric Screw

(Rocker Cover Bottom)

555679 Rocker Cover

691890 Rocker Cover Gasket*

691764 Hose Connector

694543 Rocker Arm Adjuster*

694544 Rocker Arm Stud*

699230 Hex Washer Head Metric Screw

(Cylinder Head Plate)

691343 Push Rod Guide*

698214 Cylinder Head Plate*

694088 Cylinder Head

Plate Gasket*

699482 Hex Washer Head Metric Screw*

(Cylinder Head)

557108 Stud

(Intake Manifold)

557015 Rocker Arm*

557016 Valve Cap*

557025 Valve
Retainer*

557024 Valve
Spring*

(Intake & Exhaust)

557026 Retaining
Ring*

(Exhaust)

555645 Valve Guide Bearing*

(.002" Over)

555690 Heat Disperser (Optional)

557133 Cylinder Head Assembly

557045 Exhaust Manifold

557047 Exhaust Gasket

WORLD FORMULA ENGINES

557099 Washer

(Exhaust Manifold)

557097 Stud (Exhaust Manifold)

557039 Spark Plug

555646 Nut*

(Intake Manifold)

557099 Washer*

(Intake Manifold)

693517 Push Rod

557098 Valve Tappet

*Included with 557133 Cylinder Head Assembly

55698 Cylinder Head Gasket*

557017 Intake Valve*

557018 Exhaust Valve*

5

WORLD FORMULA housing & flywheel

Not for

Reproduction

(Engine Model Series 124335)

WORLD FORMULA ENGINES

555568 Stop Wire

(Used on Type No. 8002 & 8003)

557134 Blower Housing

555629 Hex Washer
Head Metric Screw

(Blower Housing)

555577 Label Kit

557125 Magneto Armature

699477 Metric Screw

(Magneto Armature)

557126 Flywheel

699201 Screw

(Flywheel Fan)

557128 Starter Ring Gear

(Includes 4 Pcs. 557129 - Screw)

698039 Starter
Drive Cover

699201 Screw

(Starter Drive Cover)

692592 Flywheel Fan

557107 Metric Screw

(Rewind)

555255 Rewind Guard

695287 Rewind Starter

699359 Hex Jam Nut

(Flywheel - M6 x 1.5)

555629 Hex Washer Head Screw

691678 Hex Washer Head Screw

(Blower Housing - 5/16 - 18unc)

692591 Flywheel Cup

555702 Cylinder Cover Insert

(optional)

19433 Flywheel Wrench

19069 Flywheel Puller

19584 Flywheel Puller

(Optional)

6

WORLD FORMULA carburetor assembly

Not for

Reproduction

(Engine Model Series 124335)

555647 Throttle
Cable Boot

557088 Throttle
Cable Cap

557087 Throttle
Return Spring

557007 O-Ring Seal*

557130 Carburetor Spacer+

555650 Needle Valve
Retainer

(Contains 5 Clips & 5 Retainers)

690939 Nut+

(Carburetor)

555586 Idle Speed Kit

557081 Needle Jet

557083 Throttle Valve

698973 Air Cleaner

557096 Air Cleaner

Pilot Jet

557086 Emulsion Tube

557012 Main Jet

(Gasoline - Contains: 30 & 34 mm Pilot Jets: 93, 95,
96 & 100mm Main Jets)

(Water Repellent Cover,

Optional)

WORLD FORMULA ENGINES

557131 Clamp

(Intake Manifold)

555585 Idle Mixture Kit

557009 Intake Manifold

557044 Intake Gasket*

557082 Float Bowl Gasket*

555610 O-Ring Seal

557006 Carburetor Assembly

(Does not contain Carb Spacer, Clamp,
Manifold, Gasket, Air Cleaner or Main Jet)

*557089 Carburetor Overhaul Kit

+555646 Metric Screw/Nut Kit (Carb to Spacer)

555607 Carburetor Bowl Drain

555648 Needle Float Valve

*

557080 Carburetor Float

100094 Air Cleaner
Recharging Kit

(Optional)

557008 Float Bowl

7

WORLD FORMULA clutch

Not for

Reproduction

(Engine Model Series 124335)

WORLD FORMULA ENGINES

557023 Centrifugal Clutch Assembly

(Does not contain Radius Washer 2400025)

557116 Cartridge Springs Kit

(Includes 3 Orange & 3 Yellow)

557115 Snap Ring

557111 Clutch Drum

557115 Snap Ring

2400025 Raduis Washer

(Required for inboard mounting,
included with Clutch Assembly)

557020 Clutch Gear (17T, #219)
557021 Clutch Gear (16T, #219)
557092 Clutch Gear (19T, #219)
557091 Clutch Gear

(18T, #219)

557114 Clutch Cartridge

(Includes Springs)

557112 Clutch Hub Shaft

557113 Clutch Thrust Spacer/Bearing

557019 Mounting Hardware

8

WORLD FORMULA starter assembly

Not for

Reproduction

(Engine Model Series 124335)

*Included with 557068 Starter Assembly

+Included with 557073 Brush Retainer

691293 Brush Retainer*

497608 Brush Set*+

557072 Starter Housing*

692966 Starter Armature*

557120 Screw

(Support Bracket)

557119 Support Bracket

(Starter)

691286 End Cap*

691029 Nut*+

(Brush Retainer)

691261 Washer*+

(Brush Retainer)

557067 Starter Solenoid

690323 Screw*

(Starter Motor)

691532 Starter Strap

690635 Clamp

(Starter Solenoid)

WORLD FORMULA ENGINES

692353 Pinion Gear

790537 Screw

(Starter Motor Mounting M8 x 1.25)

694482 Drive Cap*

691265 Retaining Ring

499308 Starter Drive*

9

WORLD FORMULA control bracket & gasket set

Not for

Reproduction

(Engine Model Series 124335)

WORLD FORMULA ENGINES

699479 Metric Screw

(Control Panel)

555699 Control Panel

808656 Fuel Pump

793379 Stop Wire

(Used on Type No.(s) 8104, 8105, 8106)

692602 Stop Wire

(Rocker Switch,
Used on Type No. 8002

557028 Starting Switch

)

*Included with 557110 Engine Gasket Set

+ Included with 557027 Valve Gasket Set

557044 Intake Gasket*+

699485 Crankcase Gasket*

299819s Oil Seal*

(Magneto Side)

(PTO Side)

694088 Cylinder Head Plate Gasket*+

691890 Rocker Cover Gasket*+

555698 Cylinder Head Gasket*+692550 Oil Seal*

10

PZ26 Carburetor Tuning Guide

Not for

Reproduction

If a smooth idle cannot be obtained with the Idle Mixture
screw between 1/4 - 2 turns out from closed, a different
size Pilot Jet may be needed. The proper size Pilot Jet will
allow for smooth acceleration from an idle and steady
engine speed up to 1/4 throttle opening.

Midrange / Part Throttle

The Jet Needle primarily controls fuel ow between 1/4
and 3/4 throttle opening. The Jet Needle has ve notches
and a C-clip on the top of it. To richen the part throttle
operation, move the clip to the next lower notch. This will
hold the needle farther out of the nozzle. To lean the
part throttle operation, move the clip to the next higher
position. The highest notch (farthest from the narrow tip)
is considered the 1st position. Needle taper reference
letters are stamped on the needle for identication.

High Speed / Full Throttle

The Main Jet controls the fuel ow at throttle positions of
1/2 to full throttle. The jet size or diameter in millimeters
is stamped on the jet. Altitude and weather conditions can
effect the engine operation enough to require changing
the size of the Main Jet. High air temperature, humidity, or
altitude could require a smaller Main Jet. Low temperature,
humidity, or altitude would require a larger diameter Main
Jet. Running the engine with an improper Main Jet could
result in a loss of power, high engine temperatures, or
engine damage.

WORLD FORMULA ENGINES

Float Height

The oat height controls the fuel level in the oat bowl,
which can also effect carburetor performance. Set oat
height according to specication before any other tuning.
The oat height may need to be adjusted for best perfor­mance on different track types.

Idle / Low Speed

Tuning of the engine at idle and low speeds is accomplished
by adjusting the Idle Mixture Screw or changing the size of
the Pilot Jet (also called Slow Jet). The jet size or diameter in
millimeters is stamped on the jet (37 = .37mm orice). The
Idle Mixture Screw is a fuel adjustment, so closing the screw
or turning it clockwise will lean the fuel mixture, and opening
the screw or turning it counterclockwise will richen the

fuel mixture.

To adjust the Idle Mixture Screw proceed as follows. Turn
the Idle Mixture screw in until it lightly seats or stops. Back
the screw out the specied number of turns. Warm the
engine and set the Idle Speed screw slightly higher than
the desired idle rpm. Turn the Idle Mixture screw in or out
to obtain the highest rpm. Turn the Idle Speed screw to the
desired idle rpm. A slightly rich idle mixture is usually better
for acceleration.

PZ Carburetor General Specifications

Gasoline
Main Jet - #102
Pilot Jet - (Slow Jet) #37
Jet Needle - CDB 4th notch
Main Nozzle diameter - 2.6 mm
Idle Mixture Screw turns out - 1-1/2
Float Height* - 14.0mm
Torque Specifications
Bowl Screws 17 – 20 in-lbs.
Pilot Jet 9 – 12 in-lbs.
Needle Jet 14 – 16 in-lbs.
Main Jet 9 – 11 in-lbs.

11

WORLD FORMULA electric starting system

Not for

Reproduction

(Engine Model Series 124335)

WORLD FORMULA ENGINES

Electric Start Wiring Diagram

12

Log Book

Not for

Reproduction

DATE WORK PERFORMED SEAL NUMBER WORK PERFORMED BY

1/31/08 example: Replaced Air Cleaner DK

13