Crankshafts, Bearings and Crank Components at Easy Life Markets
Crankshafts turn the up-and-down motion of the pistons into the rotation that drives your vehicle, and this category at Easy Life Markets covers the crankshafts and the parts that keep them turning: complete crank assemblies, main bearings, crankshaft position sensors and the tools used to work on them. Our current range is aimed mainly at motorcycles, scooters and small engines, with bearings, a sensor and a pulley holding tool for car engines.
So what should you buy? If a small engine has a knocking bottom end or a worn connecting rod, a complete crankshaft assembly is usually the simplest fix. If a car engine is being rebuilt, main bearings matched to the crank size are the key part. If the engine cranks but will not start and shows a crank sensor code, start with the sensor. The current price and availability are shown on each product page.
What a Crankshaft Does
A crankshaft is a shaft with offset sections called crankpins. Each connecting rod links a piston to one of these crankpins. When combustion pushes the piston down, the rod pushes the crankpin round, and the shaft rotates. The main journals sit in bearings in the engine block or crankcase and carry the load. Counterweights opposite the crankpins balance the rotating mass so the engine runs smoothly.
The crankshaft also drives other parts. At the front it turns the timing chain or belt that drives the camshafts, and often the accessory belt through a pulley. At the back it bolts to the flywheel or flexplate, which connects to the clutch or torque converter. The crankshaft entry on Wikipedia explains the layouts, from single-cylinder cranks to multi-throw car designs.
Car crankshafts are one-piece forgings or castings that run in split shell bearings. Many small two-stroke and four-stroke engines use built-up crankshafts, where the flywheels, crankpin and connecting rod are pressed together and the rod runs on a needle bearing. That difference affects how they are repaired. A built-up crank is usually replaced as an assembly. A one-piece car crank can often be reground and fitted with undersize bearings.
Main Product Types in This Category
Complete Crankshaft Assemblies
For small engines, a complete assembly with the connecting rod fitted saves a lot of work. You do not need a press or a truing stand to rebuild the old one. Our off-road motorcycle crankshaft assembly with connecting rod is built for dirt bike engines, and the MS440 chainsaw crankshaft and connecting rod assembly is listed for Stihl MS 440 chainsaws. Check the listing details against your engine before ordering.
Scooter Crankshafts
Scooter engines such as the GY6 family are common and easy to work on, but the crank must match the engine size and the drive side. The GY6 50cc crankshaft for 50cc and 80cc scooter engines is offered with 16 or 22 teeth and is listed as 45# steel. The tooth count matters because it must suit the oil pump drive or timing gear on your engine, so count the teeth on your old part.
Main Bearings
Main bearings are the thin shells that the main journals turn in. They are separated from the crank by a film of oil. Wear, low oil pressure or dirty oil causes knocking and low pressure readings. When a car engine is rebuilt, the bearings are replaced as a set. Our 21020-2G100 main bearing set contains 10 pieces and is listed for the Genesis and Hyundai engines named on its page.
Crankshaft Position Sensors
The crankshaft position sensor reads a toothed wheel or reluctor on the crank and tells the engine computer the crank position and engine speed. Without that signal most modern engines will not start. Typical signs of failure are a no-start, stalling when warm, rough running and fault codes. We carry the 12560228 crankshaft position sensor (213-354) for Buick and Chevrolet. Other engine sensors are in our sensors category.
Crankshaft Pulley Tools
The crank pulley bolt is often very tight, and the crank wants to turn when you try to undo it. A holding tool locks the pulley so you can remove the bolt safely without using the starter or wedging tools in the engine. The crankshaft pulley holding tool set with carry case is in this category for that reason. For more workshop tools, see our tools and equipment category.
Crankshafts and Related Parts Compared
| Part | Main job | Usual reason to replace | Who usually fits it |
|---|---|---|---|
| Built-up crank assembly | Crank and rod as one unit for small engines | Rod bearing play, knocking, seized engine | Experienced home mechanic or small engine shop |
| One-piece car crankshaft | Main rotating shaft of a car engine | Damaged journals, cracks, engine rebuild | Engine builder or workshop |
| Main bearing set | Supports the crank journals on an oil film | Low oil pressure, knocking, rebuild | Engine builder or workshop |
| Crankshaft position sensor | Reports crank position and engine speed | No-start, stalling, sensor fault codes | Home mechanic or workshop |
| Pulley holding tool | Holds the crank pulley while the bolt is turned | Needed for timing and pulley jobs | Anyone doing front-of-engine work |
How to Choose Crankshafts and Bearings
Bottom-end parts must match closely. A small difference in size or design can stop an engine going together, or worse, cause it to fail soon after. Use these checks.
Match the Engine, Not Just the Vehicle
One motorcycle model may use different engines over the years, and one car model may offer several engine codes. Find the engine code or engine type and match it to the listing. For small engines, measure the old crank: overall length, shaft diameters and the taper or thread on each end.
Check Stroke and Connecting Rod Length
Stroke is the distance the piston travels, set by how far the crankpin is offset. Changing stroke changes engine capacity and piston position at top dead centre. For a simple repair, buy the same stroke as the original. Stroker cranks are a performance change and need matching pistons and checks of clearances.
Count the Teeth and Check the Drive Side
Many small engine crankshafts carry a gear or have splines that drive the oil pump, the timing chain or the clutch. Count the teeth and check the spline type. The GY6 listing offers 16 or 22 teeth for this reason.
Bearing Size and Grade
Car main bearings come in standard size and in undersizes for reground cranks. Some engines also use colour or number grades to fine-tune clearance. Measure the journals or take the crank to a machine shop. Never fit standard bearings on a reground crank or the other way round. Check the size given on the listing.
Sensor Connector and Mounting
For a crankshaft position sensor, match the part number, the connector shape and the mounting. Some engines use a sensor in the block and some at the front pulley or the flywheel. Compare your old part with the listing photo.
Material and Build
Crankshafts for road use are forged or cast steel or cast iron. Forged cranks are generally stronger, which matters for high-stress engines. For standard replacement in a small engine, a steel crank built to the original design is the normal choice. Our listings state the material where it is known.
Common Signs of Crankshaft Problems
- Deep knocking from the bottom of the engine that gets louder with load is a classic sign of worn rod or main bearings.
- Low oil pressure warning at idle when the engine is warm can mean bearing clearances have grown.
- Side-to-side play in the connecting rod on a small engine, or up-and-down play you can feel, means the crank assembly is worn.
- Vibration that was not there before can come from a damaged crank, a failed harmonic balancer or worn mounts.
- Engine turns over but will not start, with a crank sensor code, usually points to the sensor or its wiring.
- Oil leaking from the front or rear of the engine may be a crank seal. Seals are often replaced during crank work. See our gaskets category.
If the vibration feels like it is coming from the engine moving on its mounts, check our engine mounts category as well.
Fitting and Care Tips
Crankshaft and bearing work is precise. It needs clean conditions, the right measuring tools and the service manual for your engine. If you have not done bottom-end work before, ask a qualified mechanic or engine builder.
- Keep everything clean. Dirt between a bearing and a journal causes scoring within minutes. Clean the oil passages and blow them through.
- Measure clearances. Use the method in your service manual to check bearing clearance and crank end float. Do not assume a new part is right without checking.
- Lubricate on assembly. Coat bearings and journals with assembly lube or clean oil as the instructions say.
- Follow the manual for bolts. Main cap and rod bolts often have a set sequence and may be one-use. Use the figures in your manual.
- Replace seals and gaskets. Once the crankcase is open, fit new crank seals and case gaskets.
- Prime the oil system. Before the first start on a rebuilt engine, make sure oil pressure builds.
- Look after the oil. Use the oil grade your vehicle maker sets and change it on time. Most bearing failures start with poor oil.
For two-stroke engines, use the correct oil mix ratio. A lean mix starves the crank bearings and rod of lubrication.
How Crankshafts Differ Between Engine Types
It helps to know what kind of crank your engine has before you shop, because the repair approach changes with the design.
Single-Cylinder Engines
Most small motorcycles, scooters, chainsaws and garden machines have one cylinder and one crankpin. The crank is usually a pair of round flywheels joined by the crankpin, with the rod running on a needle or roller bearing. These are pressed together at the factory and trued so the shaft runs straight. Home rebuilding is possible with a press and dial gauge, but buying a complete assembly is quicker and avoids alignment errors.
Two-Stroke and Four-Stroke Cranks
In a two-stroke engine the crankcase is part of the intake system. The crank seals must hold pressure, and the bearings depend on the oil in the fuel mix. In a four-stroke engine the crank sits in an oil bath or is fed by a pump. A two-stroke crank is not a substitute for a four-stroke crank, even in a similar size.
Multi-Cylinder Car Engines
Inline four, six and V engines use a one-piece crank with several crankpins arranged at set angles. The angle between the pins sets the firing order and how smoothly the engine runs. These cranks are heavy, precise and usually machined at an engine shop rather than replaced at home.
Quick Buying Checklist
- Engine code or engine type confirmed
- Old part number noted and compared with the listing
- Stroke, length and shaft ends measured on small engine cranks
- Gear tooth count and spline type checked
- Bearing size known, standard or undersize
- Seals and gaskets ordered for the same job
- Service manual on hand for clearances and bolt figures
Ticking these off before you order saves returns and time in the workshop.
Who This Category Suits
- Dirt bike and scooter owners rebuilding a worn bottom end with a complete crank assembly.
- Small engine repairers working on chainsaws and similar machines.
- Car engine rebuilders who need a bearing set matched to a specific engine.
- Home mechanics replacing a crank sensor or doing a timing job that needs the pulley held.
Our Current Range of Crankshafts and Crank Parts
Our current range includes six products. It is a small selection, and we plan to add more crankshafts and bottom-end parts over time.
- Off-road motorcycle crankshaft assembly with connecting rod
- GY6 50cc crankshaft for 50cc and 80cc scooters, 16 or 22 teeth
- MS440 chainsaw crankshaft and connecting rod
- 21020-2G100 main bearing set, 10 pieces
- 12560228 crankshaft position sensor
- Crankshaft pulley holding tool set
Each product page lists the engines and reference numbers it is meant for. Read those notes and compare them with your engine before you order.
Related Engine Categories
Crankshafts belong to our engine parts category, which sits inside the main auto parts department. If your job covers more of the engine, these sibling categories help:
- Pistons and cylinder kits, often replaced with the crank in small engines, such as the GY6 125cc piston kit
- Camshafts, lifters and cam sensors for the top end
- Timing belts and chains driven from the front of the crank
- Engine blocks for major rebuilds
Frequently Asked Questions
Can a crankshaft be repaired, or must it be replaced?
One-piece car crankshafts can often be reground by a machine shop and fitted with undersize bearings, if the damage is not too deep. Built-up small engine crankshafts are usually replaced as an assembly, which is why we sell them that way.
How do I know which bearing size I need?
Measure the crank journals or have a machine shop do it. Standard bearings suit a standard crank. A reground crank needs the undersize that matches the grind. Check the size on the listing before ordering.
What causes crankshafts to fail?
The most common causes are oil starvation, dirty oil, overheating and over-revving. In two-stroke engines, a lean oil mix is a frequent cause. Good oil and correct maintenance prevent most failures.
Will a bad crankshaft position sensor stop the engine?
On most modern engines, yes. The computer needs the crank signal to time fuel and spark. A failing sensor may also cause stalling when hot or intermittent no-starts.
Do I need a special tool to remove the crank pulley?
On many engines a holding tool makes it much safer and easier. It stops the crank turning while you loosen the bolt. Our crankshaft pulley holding tool set is made for this job.
Can I fit crankshafts myself?
A small engine crank assembly can be fitted by an experienced home mechanic with the right manual. Car crankshafts and bearings need precise measurement, so we recommend a workshop or engine builder.
Not sure about fitment?
Send us your engine details and part numbers through our contact page. Our FAQ page answers common order questions, and the return and refund policy explains what to do if something is wrong.
How does shipping work?
Shipping details are set out on our shipping policy page. Please check there for current information before you buy.
Shop Crankshafts and Bottom-End Parts at Easy Life Markets
Easy Life Markets sells crankshafts, crank assemblies, main bearings, crank position sensors and pulley tools for the engines named on each listing. Measure first, match the engine and part number, and replace bearings and seals as a set when the engine is open. Strong bottom-end work starts with the right parts, and our team is happy to help you check fitment before you buy.