OFNA Racing Hyper 21 User Manual

HYPER .21 ENGINE

Thank you for purchasing an OFNA engine. We appreciate your choice and know you will enjoy running it.

Carburetor Low end and barrel stop screws are preset by factory.... Do not change until break-in is done.

NEW ENGINE BREAK-IN

Your OFNA engine is extremely tight when the piston is at the top of the stroke, this is normal for a new ABC type engine.
The piston and sleeve are matched for fit and the top of the sleeve is tapered for a tight compression fit. As you run your
engine, this tightness
expand faster than the aluminum piston and the engine will turn freer.

As with any new engine, there are many high spots and tight fits in the matching process. High spots create hot spots that
must be broke-in. Therefore, the break-in process is very important to provide good service by the OFNA engine. We
recommend using one gallon of 20% SIDEWINDER as break-in fuel. Other break-in type fuels or added oil is NOT needed
DO NOT OVER REV THE ENGINE WHEN FIRST STARTING, this could break the piston and over heat the sleeve. Always
stop engine and set piston to the bottom of the stroke when finished.

STARTING ENGINE FOR THE FIRST TIME

There are three needles on the carburetor. Do not touch any needles until you read and understand this procedure. Set the
needles as follows to start the break-in process.

should diminish. There is no cause for alarm, because as the engine warms up, the brass sleeve will

Set the master needle IN until stops, then turn OUT 3.5 to 4 turn.

To reset factory setting for both low-end needles, check figures. Setting for the black low end needle (see fig.) is OUT 1/2
turns out from flush. Setting brass head mid range needle, should always be flush to the case.

Install Standard Glow Plug with one brass washer.

To start engine, prime fuel line by placing finger over pipe outlet and pulling the engine over 5 times. This will push fuel to
the carburetor. Place glow plug heater on engine plug, pull the starter handle with short quick pulls. Engine should start
immediately. If not, check fuel line for fuel and that needle has been set correctly.

Heat cycle the engine during break-in procedure. This means, set an idle on the engine (adjust idle RPM screw so the
clutch is not engaged) and let it run without the car moving (hold car on the ground) for 3 minutes. Stop engine and let it
cool down with piston turn down on a bottom stroke and not at top dead center.

After engine is cool, start engine up again and repeat the cycling 3 times.

After heat cycling engine release the car and throttle it up and down. DO NOT OVER REV ENGINE, keep engine going
with short burst of speed. You can now turn IN the master needle a 1/4 turn to improve performance. Keep adjusting
needle until engine is running at a good speed without being too hot. Remember to always check engine temperature (it
should not exceed 250 degrees) normal temperature for best engine life is 220 degrees

GNITTESELDEENLAMRONSGNITTESELDEENNI-KAERB

TUOSNRUT3.5-ELDEENRETSAM•TUOSNRUT4-ELDEENRETSAM•

• LOW-END(BLK) NEEDLE - 1 TURNS OUT FROM FLUSH • LOW-END(BLK) NEEDLE -1/2 TURNS FROM FLUSH

• MID/LOW-END(BRASS) NEEDLE - FLUSH • MID/LOW-END(BRASS) NEEDLE - NO TURNS

HYPER .21 ENGINE

NEEDLE FUNCTION

Master Needle Valve - main control for fuel mixture. Set at 3.5 to 4 turns out from closed OR 1/2 turns in from top flush.
Adjust this needle for maximum RPM and power without being too lean or too hot. Make sure you start at bottom of needle
seat!!

Side Black Carburetor Needle (Low End) - This needle is in the center side of the carburetor barrel and provide throttle
response. It is not the idle adjustment. Set 1/2 turns out from FLUSH with the black ball sleeve. Turning IN is Lean
and OUT is Rich. Do not adjust this needle until the Master Needle is set for power and top speed. This will only effect
throttle response.

Mid Range Needle (brass) - DO NOT ADJUST MID RANGE NEEDLE, FACTORY SETTING IS FLUSH TO CASE.

Barrel Stop Screws - Used for adjusting Idle. Set for 1/16th inch gap to start new engines. You can open more for faster
idle. Set idle below clutch engagement.

USE LONG GLOW PLUG WITHOUT IDLE BAR,

OFNA #51010 HOT OR #51011 MEDIUM.

SHOWN AT
"FLUSH
SETTING"

MASTER NEEDLE
FACTORY SETTING: 3.5 to 4 TURNS OUT FROM CLOSE
FUNCTION: SET MAX SPEED AND POWER.

LOW END NEEDLE
FACTORY SETTING:
HEAD IS FLUSH WITH BALL COLLAR
SET: 1/2 TURNS OUT
FUNCTION: ADJUSTS THROTTLE
RESPONSE.

MID RANGE NEEDLE

DO NOT TURN!

FACTORY SETTING: HEAD IS
FLUSH TO CASE

BARREL STOP OR
IDLE SCREW
FACTORY SETTING:
1/16 AIR GAP