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return to shopDownload the manual that matches your bike. The F14R12 and F17R14 manuals are identical except for tire sizes, dimensions, weight, fuel capacity, seat height and one torque-table row. If you are unsure which version you own, use the size table in "Which FX125 version do I have" below.
Manual PDF: FX125 F14R12Manual PDF: FX125 F17R14Shop FX125
FX125 quick facts
The FX125 uses a single-cylinder 125cc air-cooled 4-stroke engine with a 4-speed manual clutch, hydraulic disc brakes front and rear, and a 264.55 lb (120 kg) maximum load. Values below come from the technical specification page of the owner's manual; where the two versions differ, each has its own column.
| Item | F14R12 | F17R14 |
|---|---|---|
| Engine | Single-cylinder, 125cc, 4-stroke, air-cooled, single overhead camshaft | |
| Starting | Kick start and electric start | |
| Rated power | 6.5 kW at 7,500 rpm | |
| Max. torque | 8.8 Nm at 5,500 rpm | |
| Max. no-load rpm | 9,000 rpm | |
| Bore x stroke | 54 x 54.5 mm | |
| Carburetor | PZ26 | |
| Transmission | 4-speed manual clutch (4 forward gears) | |
| Brakes | Front disc and rear disc (hydraulic) | |
| Tires (off-road, bias-ply, tube type) | Front 60/100-14, rear 80/100-12 | Front 70/100-17, rear 90/100-14 |
| Seat height | 28.15 in | 33.86 in |
| Wheelbase | 41.34 in | 49.21 in |
| Length x width x height | 59.65 x 26.77 x 37.80 in | 70.1 x 30.7 x 44.1 in |
| Net weight | 144.98 lb (65.9 kg) | 163.9 lb (74 kg) |
| Fuel capacity | 1.16 gal (4.4 L) | 1.189 gal (4.5 L) |
| Max load (rider) | 264.55 lb (120 kg) | |
| Max permissible gradient | 28 degrees | |
| Fuel | Unleaded gasoline, 90 octane or higher; never gasoline mixed with oil | |
| Engine oil | 10W-40 or 10W-50 (the manual gives no oil quantity) | |
| Brake fluid | DOT 4 only | |
| Tire pressure (cold) | 15-18 psi (104-124 kPa), front and rear | |
| Top speed | About 56 mph (product-page figure; the manual does not state a top speed) | |
Which FX125 version do I have: F14R12 or F17R14?
Check the tire sizes and seat height: F14R12 has a 14-inch front wheel and 12-inch rear wheel with a 28.15 in seat, and F17R14 has a 17-inch front wheel and 14-inch rear wheel with a 33.86 in seat. The tire size is molded into each tire sidewall.
| What differs | F14R12 | F17R14 |
|---|---|---|
| Wheel size (front / rear) | 14 in / 12 in | 17 in / 14 in |
| Tire size | 60/100-14 front, 80/100-12 rear | 70/100-17 front, 90/100-14 rear |
| Seat height | 28.15 in | 33.86 in |
| Wheelbase | 41.34 in | 49.21 in |
| Net weight | 144.98 lb | 163.9 lb |
| Fuel capacity | 1.16 gal | 1.189 gal |
| Torque table | 4 rows (no handlebar clamp bolt row) | 5 rows (adds handlebar clamp bolts, 40.5 Nm / 30 ft-lb) |
Everything else in this guide (engine, oil, fuel, break-in, maintenance intervals, troubleshooting) applies to both versions. To identify the exact bike for warranty or parts, the manual lists the VIN in three places on the chassis: right side of the frame, left side of the frame, and the steering head tube. The engine model and serial number are stamped on the left side of the engine, under the countershaft sprocket.
Tools and supplies the FX125 manual calls for
The manual does not include a packing list or a tool list, but its procedures name the tools below. Have them ready before you build or service the bike.
- Tire pressure gauge (cold pressure 15-18 psi).
- Small adjustable wrench or spoke wrench for spokes.
- 5/8 in socket or wrench and a spark plug gap tool (gap 0.5-0.8 mm) for the spark plug.
- Phillips screwdriver for the brake master cylinder cap screws.
- 8 mm wrench for the brake bleeder valve.
- Needle-nose pliers for the chain master link clip.
- Funnel and oil drain pan; fresh 10W-40 or 10W-50 oil.
- Fresh, sealed DOT 4 brake fluid.
- Chain lube or 80W/90W gear oil; air filter oil for the air filter.
- Tachometer, if you adjust idle speed.
- A support stand or the side stand on firm, level ground.
FX125 assembly
The FX125 owner's manual does not contain step-by-step assembly instructions, so FRP Moto shows assembly in video. Watch the assembly video for your version, then use the torque values and pre-ride checks on this page before the first start.
Fastener torque values the manual gives for the parts you handle during and after assembly:
| Fastener | Torque | Count | Versions |
|---|---|---|---|
| Lever clamp bolts | 35 Nm (26 ft-lb) | 4 | Both |
| Breather hose cap | 16.2 Nm (12 ft-lb) | 1 | Both |
| Swing-arm nut | 81 Nm (60 ft-lb) | 1 | Both |
| Handlebar clamp bolts | 40.5 Nm (30 ft-lb) | 4 | F17R14 table only |
| Brake-oil nut | 17.3 Nm (13 ft-lb) | 1 | Both |
| Rear axle nut (chain adjustment) | 115 Nm (85 ft-lb) | 1 | Both |
| Engine oil drain bolt (with new sealing washer) | 15 Nm (11 ft-lb) | 1 | Both |
Warning: The manual says improper maintenance, or failing to correct a problem before riding, can cause a crash in which you can be seriously hurt or killed. Check every accessible nut and bolt after assembly and tighten any that are loose.
Note: Fill the engine with the recommended oil before the first start. Check the level with the dipstick using the steps in the service specs section; the manual gives the level marks but no oil quantity.
FX125 pre-ride checklist
Inspect the bike before every ride; the manual calls this inspection a must because off-road riding is hard on a motorcycle. Check these items before you get on:
- Tires: check air pressure with a gauge and look for damage or excessive wear.
- Spokes and rims: all spokes tight, rim not bent.
- Leaks: look under the bike for engine oil or gasoline.
- Engine oil: check the level and add if needed; FRP recommends only 10W-40 or 10W-50 for off-road riding.
- Fuel: check the level and make sure the fuel cap is tight and the breather tube is connected.
- Drive chain: inspect condition and slack, adjust and lubricate if needed; check the chain guides and rollers for wear.
- Brake hoses: inspect for leaks.
- Nuts and bolts: tighten any that are loose.
- Spark plug and cap: plug snug, cap pushed on and secure.
Then, with your weight on the bike:
- Throttle: check free-play, and confirm the throttle snaps fully closed in all steering positions.
- Brakes: press the rear brake lever and squeeze the front lever to confirm both work.
Warning: The manual states the FX125 is not equipped with lights and must not be ridden at night.
How to start, shift and stop the FX125
Start the FX125 in neutral with the fuel tap ON, the choke lifted, the brake lever held and the throttle open no more than 1/4; then kick-start it or press the electric start switch. Never start the engine with the transmission in gear.
Cold start
- Turn the ignition to ON (the manual says "key switch") and make sure the stop/run switch is set to Run.
- Make sure the transmission is in neutral.
- Turn the fuel tap to ON.
- Lift the choke lever up (closed).
- Press and hold the brake lever on the right side of the handlebar.
- Open the throttle no more than 1/4 of the way.
- Kick start: extend the kickstart lever and, from the top of the stroke, kick firmly through to the bottom in one smooth motion. Electric start: press the electric start switch and release it as soon as the engine starts.
- After about 1 minute of running, push the choke lever down.
- Let the engine warm up for about 5 minutes before riding.
For a warm start, repeat the same steps except the choke step, as the manual lists (steps 1, 2, 3, 5, 6, 7 and 8).
Shifting
The FX125 has four forward gears, and neutral sits between first and second. Close the throttle before every shift.
- With the engine warm and the side stand up, close the throttle fully and select first gear. The shift lever returns to its neutral position after you release it.
- Open the throttle slowly. When you feel the clutch begin to grab and the bike eases forward, you are in the friction zone; keep opening the throttle gradually.
- At moderate speed, close the throttle, lift the shift lever until it clicks into second, then reopen the throttle smoothly. Repeat for higher gears.
- To downshift, close the throttle, press the shift lever down until it clicks, then reapply the throttle smoothly.
- To find neutral, pull the clutch in and press the lever down into first, then lift it about half the distance of an upshift. You can also find neutral from second by pressing down half the distance of a downshift.
Stopping and parking
Pull the clutch in when slowing to a stop (unless you are in neutral) so the engine does not stall, and put your left foot down first. To stop the engine, shift to neutral and press and hold the red stop switch on the left handlebar until the engine stops. Park on level ground on the side stand, and turn the fuel tap OFF when you are done for the day. For long storage, turn the fuel tap OFF while the engine is running and work the throttle until the engine stops on its own, which uses up the fuel left in the carburetor.
Flooded engine
If the engine will not start after repeated attempts, it may be flooded. The manual's steps: press the engine stop switch, open the throttle completely, kick-start several times (kick start only), remove and dry the spark plug if necessary, and once the engine starts, open the throttle to 1/4 and blip it a few times to clear excess fuel.
Braking
Apply the front brake and rear brake together, firmly and smoothly. The manual states the front brake provides about 70% of stopping power and the rear about 30%. If a wheel locks, release the brakes, steer straight, and reapply with less force. Finish braking before you enter a turn.
Warning: Do not rev a cold engine or ride it with a full load. Let it idle until warm, or ride it warm at low rpm. Do not coast or tow the bike long distances with the engine off; the manual warns this can damage the transmission.
Warning: Never run the engine in a garage or poorly ventilated area. Exhaust contains carbon monoxide.
FX125 break-in period
The first 800 km (500 miles) is the most important in the life of the bike. During break-in, keep engine speed below 3,000 rpm for the first 800 km (500 miles), below 5,000 rpm up to 1,600 km (1,000 miles), and below 8,000 rpm after 1,600 km (1,000 miles).
| Distance | Maximum engine speed |
|---|---|
| First 800 km (500 miles) | Below 3,000 rpm |
| Up to 1,600 km (1,000 miles) | Below 5,000 rpm |
| After 1,600 km (1,000 miles) | Below 8,000 rpm |
- Vary the engine speed during break-in. This lets parts load (helping them mate) and unload (letting them cool), but do not load the engine too much.
- Ride the suspension for about 2 hours on the original settings before adjusting it.
- Wear in new tires over the first 160 km (100 miles): increase cornering lean angle gradually and avoid hard acceleration, hard cornering and hard braking.
- Spokes loosen faster during the first 100 miles because the parts are seating, so check spoke tightness during that period.
- Run slowly for 3-5 minutes after start-up and before stopping; do not stop the bike suddenly.
Warning: Failing to break in new tires can cause tire slip and loss of control. Use extra care on new tires.
FX125 maintenance schedule
The manual's schedule runs in kilometers: engine oil is replaced at 750 km and then every 3,000 km, and most inspection items repeat every 3,000 km up to 15,000 km. It also says to change the oil after every 15 hours of riding. Service more often in wet, muddy or dusty conditions.
Key: I = inspect (clean, adjust or replace if needed), C = clean, A = adjust, L = lubricate, R = replace. One asterisk marks items needing moderate to high mechanical skill; two asterisks mark items needing special tools.
| Item | 750 km | 3,000 km | 6,000 km | 9,000 km | 12,000 km | 15,000 km |
|---|---|---|---|---|---|---|
| Engine oil (*) (also check the level before each ride) | R | R | R | R | R | R |
| Oil filter (*) | - | C | C | C | C | C |
| Air cleaner (*) | - | C | R | C | R | C |
| Spark plug (**) | - | I | R | I | R | I |
| Fuel filter (*) | - | R | R | R | R | R |
| Fuel system (**) | - | I | I | I | I | I |
| Fuel line | - | I | I | I | I | I |
| Valve re-seating (**) | - | I | I | I | I | I |
| Valve gap (*) | - | A | A | A | A | A |
| Idle speed (*) | - | A | A | A | A | A |
| Drive chain (*) | - | I, L | I, L | I, L | I, L | I, L |
| Throttle operation | - | I | I | I | I | I |
| Brake shoes / pad wear | - | I | I | I | I | I |
| Brake system | - | I | I | I | I | I |
| Brake fluid | - | I | I | I | I | I |
| Clutch | - | I | I | I | I | I |
| Nuts, bolts, fasteners | - | I | I | I | I | I |
| Wheels and tires | - | I | I | I | I | I |
The manual tells owners to use genuine replacement parts purchased directly from FRP, and says that if you are not comfortable with a procedure you should contact FRP. Keep a record of all maintenance and save receipts.
Warning: Turn the engine off before any maintenance unless the procedure says otherwise. Let the engine and exhaust cool before touching them, work outdoors or with good ventilation, and keep sparks and flames away from all fuel parts. Use a non-flammable solvent such as kerosene, never gasoline, to clean parts.
FX125 service specs: oil, fuel, chain, brakes and tires
These are the adjustment limits the manual gives, in one table so each row can be quoted on its own. Fuel is unleaded gasoline rated 90 octane or higher, and engine oil is 10W-40 or 10W-50 with no additives.
| System | Spec from the manual |
|---|---|
| Fuel fill level | Fill to about 2 in from the top of the tank; cap tight; breather tube connected |
| Engine oil | 10W-40 or 10W-50; no graphite or molybdenum additives; avoid oils marked "energy conserving". To check: run at idle 3-5 minutes, wait 2-3 minutes, stand the bike upright, rest the dipstick in the hole without screwing it in, and keep the level between the two marks. Do not overfill |
| Oil change | Drain warm oil; drain bolt with new sealing washer at 15 Nm (11 ft-lb); replace after every 15 hours of riding; let new oil circulate 2-3 minutes before riding |
| Idle speed | 1,500 plus or minus 100 rpm, engine warm, transmission in neutral. Do not adjust the air/fuel mixture screw; it is factory set |
| Throttle free-play | 3-5 mm (0.10-0.20 in) |
| Clutch lever free-play | 10-15 mm |
| Spark plug | Gap 0.5-0.8 mm; resistor plug; install by hand first, then tighten with a 5/8 in socket |
| Drive chain slack | 8-10 mm vertical movement midway between the sprockets; rear axle nut 115 Nm (85 ft-lb); chain lube or 80W/90W gear oil |
| Brake fluid | DOT 4 only; sight glass level not below halfway; replace both pads when worn to 1 mm |
| Tire pressure (cold) | 15-18 psi (104-124 kPa) front and rear; replace tires before tread depth falls below 0.12 in (3 mm); replace the tube whenever you replace a tire |
| Rear shock | Ships at the softest setting; one adjuster for compression and rebound (PLUS configuration per the manual); clockwise is harder compression and slower rebound |
| Wheel spokes | Check tightness often, especially in the first 100 miles |
Warning: Do not try to repair the forks or the rear shock yourself; the manual says to contact FRP if repair is needed. Gasoline is highly flammable, so handle it outdoors with the engine stopped and clean up spills immediately.
FX125 common problems and fixes
If the FX125 will not start, check fuel first, then spark, then compression; most no-start causes are a closed fuel tap, clogged fuel line or filter, fouled spark plug, closed choke or flooded engine. The table condenses the manual's troubleshooting flowcharts.
| Problem | What to check (in the manual's order) |
|---|---|
| Engine will not start or quits | Fuel in the tank and fuel tap ON; fuel flowing to the carburetor (clogged fuel line, filter, fuel valve, tank breather hose, stuck float). Spark plug condition (flooded engine, choke closed, throttle stuck open, dirty air filter, worn piston rings). Spark test (fouled plug, bad plug cap, ignition coil, CDI box, magneto, stop switch, loose or corroded connectors). Compression: the kickstarter should feel very firm, then soften abruptly. |
| Starts, then stops quickly | Improper choke operation, dirty or misadjusted carburetor, intake manifold leak, dirty or contaminated fuel. |
| Flooded engine | Stop switch pressed, throttle fully open, kick several times, dry the spark plug if needed. |
| Wheel does not spin freely | Dragging brake or badly mounted pads, worn wheel bearings, bent axle. |
| Slipping clutch, or engine speed does not fall between gears | Adjust the clutch free-play (10-15 mm); worn clutch discs or plates, weak clutch springs, contaminating additive in the oil. |
| Engine does not accelerate | Clogged air filter, restricted fuel line or fuel filter, clogged muffler or spark arrester, choke closed, clogged tank breather hose. |
| Engine overheats or knocks | Carbon build-up in the combustion chamber, poor-quality fuel or wrong octane, lean mixture, clutch slipping, worn piston and cylinder. |
| Carburetor air screw check | Turn the air screw in until it stops (do not tighten), then back it out 1.5 turns. Also check the intake manifold, carburetor mounting bolts and gasket for leaks. |
| Steering is heavy | Excessive wheel bearing play, bent rim, loose or broken spokes, dry-rotted tires, steering stem nut too tight, damaged steering head bearings, low tire pressure. |
| Wheel wobble | Loose or broken spokes, bent rim, wheel bearing play, wheel hub not installed correctly, damaged swing-arm or frame. |
| Bike pulls to one side | Wheels out of alignment, faulty shock, damaged fork, bent swing-arm, damaged axle, frame or triple clamp. |
| Spongy brake lever or pedal | Air in the brake system. The manual's bleed procedure pumps the lever 4-6 times, opens the caliper bleeder valve with an 8 mm wrench, and repeats until no bubbles appear and the lever feels hard and firm. Also check for leaks. |
| Flat tire on the trail | Temporary fix: aerosol tire sealer or a tube patch kit. Replace the tube if the leak is severe. Do not ride on a flat tire. |
Warning: Do not touch the spark plug or plug cap while trying to start the engine; you can receive an electrical shock. Only attempt ignition timing or valve-train checks if you are qualified and have the proper tools.
If you cannot identify or fix a problem, contact FRP support (see "Where to go next" below) before riding again.
FX125 safety, riding gear and legal use
The FX125 is for off-road use only and is not street legal. It does not meet Federal Motor Vehicle Standards, has no lights, turn signals or horn, and its tires are not designed for pavement. If you must cross a paved road, get off and walk the bike across. FRP Moto does not ship the FX125 to California.
- Age and supervision: minors must ride under adult supervision. See the kids dirt bike guide for fit and age by model. Children must be trained and understand the manual's warnings. The manual also states the vehicle is not a toy.
- Rider limit: one rider only, up to 264.55 lb (120 kg). There are no passenger pegs or seat room.
- Gear: always wear a certified helmet with the chinstrap tight, eye protection, sturdy off-road boots, gloves, long pants and a long-sleeved jersey or jacket. The manual also recommends pants with knee and hip pads, elbow pads and a chest/shoulder protector. A full-face helmet gives the most protection.
- Do not ride under the influence of alcohol or drugs, in traffic, in rain or snow, or on slippery, gravel or sand surfaces the manual calls unstable.
- Do not modify the bike, remove original equipment, or change the exhaust, noise-control or emission-control parts. Tampering with noise and emissions controls is prohibited by law in the United States.
- Do not lend the bike to anyone who does not know how to operate it, and do not use it for rental, commercial or competitive racing use; the manual says racing use voids all warranties.
- Hot parts: the brake, muffler and engine stay hot after riding. Wait at least 2 minutes with the engine off before refueling, and never smoke while refueling.
- Cleaning: the manual advises avoiding pressure washers near the wheel hubs, muffler outlet, under the seat, the stop switch, under the tank, the chain and the carburetor. Never wash the bike with the engine running, and lubricate the chain after it dries.
Warning: The manual states you can be killed or seriously injured if you do not follow its instructions. Read the entire manual, and check your local laws and Department of Motor Vehicles rules before riding.
Warranty: the manual's limited warranty lists coverage for engine and drive train, front and rear suspension, and frame and swing-arm, and excludes abuse, impact damage, modification and rental or commercial use. For current FRP Moto warranty terms and owner support, see the warranty and owner support page.
FX125 assembly and parts videos
FRP Moto publishes an FX125 and FX140 Assembly and Parts playlist on YouTube. The FX125-specific videos in that playlist are the two assembly videos below.
Assembly
- How to Build Your FRP FX125-14Pro (3:13)
- How to Assemble Your FRP FX125-17Pro Dirt Bike (3:12)
- How to Assemble Your FRP FX140 Dirt Bike (3:11), for the FX140
Playlist and parts
- FRP FX125 & FX140 Assembly & Parts playlist
- FRP Moto replacement parts (use genuine FRP parts, as the manual advises)
- All FRP Moto videos and tutorials
The manual's cover also carries a QR code for an installation and maintenance/repair tutorial video for the FX125.
Where to go next
For help with your FX125, email csr@frpmoto.com or call 833-970-3777 (M-F 8am-5pm PST). Include your VIN and the version (F14R12 or F17R14) so support can find the right parts and instructions.
