< Briggs World Formula MODIFIED Quarter midget engine Race Prepped Natio – Krybaby Performance
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Briggs World Formula MODIFIED Quarter midget engine Race Prepped National Engine

$3,100.00 $3,500.00

Please provide your phone number on the check-out page.

It will take a short conversation to get the particulars of your goals so we can get you the best engine poissible.

You can also email us at: sales@krybabyperformance.com

Description

Briggs World Formula MODIFIED Quarter midget engine Race Prepped National Engine.

Wait times on this engine can be anywhere from 10-15 days depending on time of year. We Build all year round any try to have engines in stock at all times.

Briggs & Stratton World Formula Modified with gearbox race engine for Quarter Midget Racing. 

Watch the video of it on the dyno - Briggs Modified World Formula QM on the Dyno!

We build each racing engine to spec per the class and organization you will be competing in.  Every Krybaby Racing Engine is given 100% of what the rules allow  –  we build each engine to peak performance. 

This is the King of Quarter Midget Racing more power than any other engine on the market. Never run at a club level, smaller fields at a regional, and nearly a full field at a national race.

This is the Quarter Midget World Formula MODIFIED Engine - this is no run of the mill or rookie engine. This is a demanding class where 1/3 of the cars will not finish the race. Engine fails are common, bolts loosen, engines lock up, this is a high demanding engine. the oil must be changed every race. The alcohol fuel must be flushed out at the end of the day. When 12 are in the race, it takes a minute to get them all going and it is rolling thunder. They are loud and obnoxious and a blast but not for the faint of heart or low budget teams.

This is the most expensive QM engine to build. The parts list is long. The parts are expensive.  The engine is nearly $1000 and then you have to add a long list of parts that is an additional $1300. Before you are done adding up the parts you are at just over $2300 and the built has not begun. The crank will be swapped at $175, a high performance cam will be added at $185, the high rev coil is another $155, don't forget the billet flywheel at $200, add the gear box for $310 and the additional small parts are another $500.

Now we can start the build. The entire engine will come down to swap out the crank and add the gearbox and before it goes back together. The deck and head will be milled before cam inspection and 20 other points of inspection to bring you the most powerful race engine around.  For this one we want the light flywheel because the kids will be learning throttle control and this is way too much power to flat foot around lap after lap.

Briggs has been making these for many years so there are lots of old warn out ones at the tracks and they hold their value. We rebuild plenty of them but if you are serious about winning a brand new one will be king of the track.

Key Specifications of stock engine

MODEL/TYPE(S)124335 8105-01/124335 8106-01 M.A.P. Price enforced horsepower/torque11.5 hp/13 ft. lbs. torque*
Displacement204cc Bore/Stroke2.6875”/2.6885” Compression Ratio9.5 to 1
Rpm–Digitally Limited7,100 RPM Factory Timing29 degrees BTDC Fuel Type91 Octane

 

  • Reinforced, cast iron sleeved, dual ball bearing racing cylinder
  • Single cast, custom aluminum alloy cylinder head with 'kidney bean'' combustion chamber, custom seat/guide material and CNC Machined Intake D-port.
  • 2024 Billet aluminum rod with reinforced I-beam
  • Carbon steel crankshaft with induction hardened micro-polished crankpin reinforced timing gear
  • Cam ground, barrel faced, eutectic alloy domed piston with 3-piece ring set with chrome faced top ring
  • .308 max. lift ground cam with stellite-faced lobes and built in mechanical compression release
  • Dual high silicon valve springs
  • High grade stainless steel, dished valves with nitrited exhaust
  • 3-piece automotive style keepers and reinforced rocker arm and lock ball
  • Digital ignition with built in rev limiter
  • Steel hub, cast aluminum flywheel
  • Walbro 26mm round slide, fully adjustable jet carburetor
  • Custom graphoil composition, fire ring head gasket
Description Wrench / Socket Size Torque
Air Guard 7mm 40-50 lb-in. (4.5-5.6 Nm)
Blower Housing 10 mm & 3/8” 60-110 lb-in. (7-12.5 Nm)
Carburetor (to manifold) 10 mm 80-110 lb-in. (9-12.4 Nm)
Connecting Rod 5/16” 125-135 lb-in (14-15 Nm)
Cylinder Head Bolts 10 mm 200-220 lb-in. (20-27 Nm)
Exhaust Brace Screws 10 mm 95-125 lb-in. (11-14 Nm)
Flywheel Nut 15/16” 55-75 ft-lbs. (74.5-101 Nm)
Flywheel Fan 10 mm 180-240 lb-in. (20-27 Nm)
Intake (to cylinder) 5 mm Allen 70-90 lb-in. (8-10.2 Nm)
Oil Drain Plug 3/8” 100-125 lb-in. (11-14 Nm)
PVL Ignition Module 7 mm 20-35 lb-in (2.3-4 Nm)
Rocker Arm Stud 7/16 90-120 lb-in. (10-14 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 10 mm (patched, grade 8.8) 10 mm (unpatched, grade 8.8) 10 mm (SIMS patched, grade 10.8) 215-230 lb-in. (24-26 Nm) 160-175 lb-in. (18-19 Nm) 260-270 lb-in. (29-30 NM)
Top Control Cover 10 mm 70-90 lb-in. (8-10 Nm)
Valve Cover 10 mm lower & 3/8” 30-60 lb-in. (3.5-7 Nm
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