Engine Code: "BN157QMJ" 150cc stock, 12-Pole DC Fired, GY6 (A-Block) 54mm stud spacing longcase 20" fit 13" rear wheel, Chinese scooter model "ZNEN ZN150T-9" manufacture by Zhongneng Industry Group.

Chinese Scooter Parts 150cc Fit; GY6 152QMI, 157QMJ, 1P57QMJ

These GY6 engine codes will fit the majority of the Chinese scooter parts 150cc on the market. They are advertised as Chinese scooter parts for the GY6 125/150cc scooters. Due to the vast interchangeable Chinese scooter parts, these Chinese scooter parts 150cc will fit a stock GY6 125cc and GY6 150cc engine crankcase the same, for their GY6 crankcase is the same 54mm stud spacing A-Block type. Which you can learn more on blogshare about GY6 A-Block vs B-Block. Just know that GY6 152QMI, 157QMJ, and 1P57QMJ are all GY6 crankcase 54mm stud spacing A-Block. Here is a GY6 engine diagram with its GY6 crankcase attribute reference numbers.

GY6 Engine Diagram

GY6 Crankcase Attribute:

1.    Bearing 6002
2.    Bearing 6004
3.    Bearing 6301
4.    Brake Drum Actuator Dust Cover
5.    Brake Shoe
6.    Brake Shoe Anchor O-Ring 7.5X15
7.    Brake Shoe Anchor Pin
8.    Brake Shoe Arm
9.    Brake Shoe Cam
10.    Brake Shoe Spring
11.    Breather Tube
12.    Bushing 20x8x19
13.    Bushing Engine Hanger 28x10x22
14.    Crankcase (left)
15.    Crankcase (right)
16.    Crankcase Gasket (right)
17.    Dowel Pins 8x14
18.    Dowel Pins 10x14
19.    M6x50 Bolts
20.    M8 Nut
21.    M8x187.5 Cylinder Studs
22.    M8x195.5 Cylinder Studs
23.    M12 Washer
24.    M12x1.5 Bolt
25.    Oil Seal 19.8x30x5
26.    Oil Seal 27x42x7

Now that you got a visual of what a GY6 engine diagram with its GY6 crankcase attribute means. Next, you'll know how to decipher your GY6 engine code that engraves on the GY6 lower left-side crankcase. Know why a 152QMI engine code means it's a stock GY6 125cc engine size, while the other two engine codes, 157QMJ and 1P57QMj mean it's stock GY6 150cc engine size. These stock GY6 engines are air-cooled 4-strokes commonly found in Chinese scooters such as TaoTao 125cc or TaoTao 150cc. Some resellers might exaggerate their Chinese scooter parts engine size increase but in this blogshare you know how to read actual GY6 engine code, and what GY6 parts make engine size increase POWER.

GY6 engine code if we were to decipher each character for i.e. "157QMJ" the "1" means its single-piston and the "57" would mean that it has a 57mm piston with a cylinder outer skirt of 60.2mm, which may vary by manufacturer slightly off by 0.2mm thickness, allow it slip into a 152QMJ, 157QMJ or 1P57QMJ engine's crankcase bore opening 63mm max. So you can see their room for a bigger cylinder upgrade for all three 54mm stud spacing A-Block crankcases 152QMI, 157QMJ, and 1P57QMJ engine, which will be covered here on this blog

NOTE: If you have a letter “P” after example “1P”, stands for (P)air valve horizontal engine. The P series engine has a taller cylinder head and a shallow recess cam seating that gives it slightly more performance than non-P GY6’s engine code. However, if both cylinder and cylinder head is swap out it will be identical to the non-P GY6 157QMJ engine. So, both GY6 157QMJ and 1P57QMJ engines are interchangeable as long as the Chinese scooter parts 1P57QMJ top-end is replaced with 157QMJ cylinder, cylinder head, and rocker arm convert 1P to non-P. But why? Because their so many GY6 performance parts upgrade available for GY6 125/150cc non-P type engines includes a 157QMJ big bore cylinder157QMJ big valve cylinder head157QMJ rocker arm, and 157QMJ performance camshaft, etc.

The fourth code letter: “Q”

Simply means it’s a forced-air-cooled engine. "Q" means is not a liquid-cooled but forced-air-cooled engine.

The fifth and sixth code letters: “MI” or “MJ” 

The “M” means the engine type is a motorcycle(motor-cycle relates to scooters\atv\buggies as well). The sixth letter thereafter is code for engine displacement size measure in "cc" (cubic centimeter). See the table below. Notice as each alphabetical order B-to-Y so is the engine displacement CC increases incrementally 10cc, 15cc, 25cc, 50cc, and 100cc.

  • MB = 50cc
  • MC = 60cc
  • MD = 70cc
  • ME = 80cc
  • MF = 90cc
  • MG = 100cc
  • MH = 110cc
  • MI = 125cc
  • MJ = 150cc
  • MK = 175cc
  • ML = 200cc
  • MM = 250cc
  • MN = 300cc
  • MP = 350cc
  • MQ = 400cc
  • MR = 500cc
  • MS = 600cc
  • MT = 650cc
  • MU = 700cc
  • MV = 750cc
  • MW = 800cc
  • MX = 900cc
  • MY = 1000cc
  • YG = 1100cc
  • YL = 1200cc
  • Y? and so on...

GY6 engine code can help you determine what size cylinder the GY6 engines can handle or GY6 performance parts big bore kit upgrade available. As far as the GY6 125cc-150cc engine code 152QMI and 157/1P57QMJ engine it will be able to handle the biggest GY6 125/150cc Big Bore Kit slip-on available on the market the...

Taida Cylinder 61mm 171cc 2V Forged Big Bore Kit Fit 54mm (GY6)

Description: High-Quality Taida Cast-Iron Cylinder 61mm 171cc with Forged Aluminum Piston offers better durability and reduced friction for GY6 125/150cc+ engines. The cylinder bore is 61mm. Taida Cylinder Big Bore Kit Quad Combo 61mm 171cc 2V w/Forged Piston Fit 54mm including the following parts Taida 61mm (171cc) cylinder kit with forged piston, Taida oversize 2V head 28/23, Taida T300 Camshaft, and Taida 54mm rocker arm set. Taida Cylinder Big Bore Kit Quad Combo 61mm 171cc 2V is suitable for all air-cooled 4 strokes; 125-150cc Kymco engines (scooters), and most Chinese imported vehicles GY6 125/150cc (scooters, quads, and buggies).

NOTE: Please, measure with a caliper GY6 crankcase bore (opening) for 62.7mm cylinder outer diameter sleeve need a minimum 62.9mm bore clearance or boring and machining are required.


100% Taida Products – NO SUBSTITUTE.

1.    Includes Taida Cylinder 61mm 2V, Forged Piston + Rings, Gaskets (chain tensioner gasket, Hi and Low compression base gaskets, steelhead gasket), Wrist pin, Locking rings, and Taida Sticker.

  • 61mm Forged-Alumin Piston*
  • 61mm Piston Rings (installed)
  • 36mm x 15mm Wrist Pin w/G-clips
  • 61mm Cast-Iron Cylinder
  • 62.7mm Outer Sleeve Diameter
  • 69.3mm Cylinder Height (w/o sleeve)
  • 90mm Overall Height (w/sleeve)

2.    Includes Taida Cylinder Head 61mm 2V NON-EGR, Valves Assembly, Gaskets (manifold spacer +gasket, steel exhaust gasket), intake\exhaust studs, nuts, and Taida Sticker.

  • 2 Valve Head: 28mm Intake / 23mm Exhaust / Shaft Diameter: 5mm
  • Factory Ported: 27.5mm Intake / 26.5mm Exhaust
  • 60mm Cylinder Head Height (w/o valve)
  • 69mm Overall Height (w/intake valve)
  • 6mm Intake Studs
  • 8mm Exhaust Studs w/Nuts

3.    Includes Taida Camshaft T-300 2V 6.3/6.25, High Rev

  • Intake lift: 19.4mm - Lobe Greatest: 25.7mm
  • Exhaust lift: 19.2mm - Lobe Greatest: 25.45mm
  • Sprocket Teeth: 34

4.    Includes Taida Rocker Arm 2V Assembly

  • Camshaft Holder
  • Rocker Arm +Shaft (inlet)
  • Rocker Arm +Shaft (outlet)
  • 2x Valve Adjusting M5x0.50mm Tappets 
  • 2x Valve Adjusting M9x5mm Nuts
  • Made in Taiwan


Optional: cut plastic fan shroud for best fitment

Supported Models: GY6 152QMI 157QMJ Chinese Scooter, ATV, Genuine Buddy, Kymco, Ruckus, Vento.


Item Weight & Product Dimensions:

  • 2.931 pounds | 5.5" (L) x 4.972" (W) x 3.582" (H)
  • 2.316 pounds | 5.82" (L) x 5.310" (W) x 2.718" (H)
  • 0.619 pounds | 3.05" (L) x 2.625" (W) x 1.259" (H)
  • 0.528 pounds | 4.457" (L) x 2.875" (W) x 1.062" (H)

After replacing those cheap Chinese scooter parts 125\150cc with a quality Taiwanese GY6 Big Bore Kit 171cc you want to upgrade more GY6 performance parts to handle bigger engine displacement "CC" power like a GY6 Performance CVK 30mm carburetor by NCY. Perfect for GY6 Big Bore Kit 171cc+ upgrades!

NCY Carburetor CVK 30mm (GY6)

Description: NCY 30mm CVK Carburetor made by Keihin for your GY6 150cc scooter. Includes auto choke. This carb will help your performance engine breathe easier and goes well with a big-bore cylinder.

NOTE: Will fit Buddy 150 with some modifications.


  • Auto Choke
  • Accelerator Pump
  • 2 Cable/Rear Pull Linkages
  • Throttle Adjustment Knob
  • Open & Adjust Enricher Screw


  • Airbox Side ID: 43mm / OD: 47mm
  • Engine Side ID: 30mm / OD: 36mm
  • Venturi: 30mm


  • Main: 128 (5mm Thread) CVK Style
  • Pilot: 40s (6mm Thread x L: 28mm) CVK Style

Compatible jets-

Main: CVK 1300-1015 - 1300-1045, 1300-1062 - 1300-1065

  • Fit Air-Filter Port ID: 3mm max. ± 47mm
  • Fit Intake Manifold 2mm max. ± 34mm
  • Fit 54mm Stud Spacing (A-Block)
  • Fit 57mm Stud Spacing (B-Block)
  • Fit GY6 125/150cc+

Supported Models: GY6 152QMI 157QMJ 161QMK 161QML Chinese Scooter, ATV, Genuine Buddy, Kymco, Polaris RZR 170, Ruckus, Vento


Item Weight & Product Dimensions:

  • 1.425 pounds | 4.938" (L) x 4.350" (W) x 3.564" (H)

Here how to determine your actual power displacement small engine is always measured in a cubic centimeter (cc) not horsepower like cars. 

Here what it would look like Naraku Cylinder 52.4mm w/Piston. Keep in mind the only thing that affects engine power increase top-end speed is just that the top-end changes the cylinder jug w/piston and its paired crankshaft stroker length. That it. The CVT/Transmission Kit can only help make engagement at the wheel faster but not add top-end miles per hour gain. With that said here is my calculation engine displacement power of what you could have gotten with Naraku 52.4mm BBK with standard crankshaft 41.4mm and with an extended crankshaft 44mm installed:

You can use the same "Engine Displacement Calculator" the links are below. And, there are many more high-quality aftermarket scooter parts available at the NCY STORE. So if your OEM Chinese scooter parts fail or get bogged down, let NCY Performance Scooter Parts be your source for finding better and upgraded replacement parts for your GY6 125/150cc scooter.

To check out the latest GY6 CVT Transmission performance parts and accessories, click here.


Check out the related link Engine Displacement Calculator

Check out related video 157QMJ vs 1P57QMJ: