YX 50cc Engine – Electric Start (Manual) – Kit 4

The new generation of 50cc engine from the YX factory. We had a selection of horizontal 4-stroke 50cc engines arrive in our warehouse, they were all installed into several identical motorcycles and tested for acceleration and top speed, The YX 50cc came out leaps and bounds above the competitors, easily beating the Lifan, Zongshen and the GN, we do not have the exact bhp but do know this is a great and powerful engine given the low displacement of a 50cc engine.

The YX 50 engine is one of the most reliable learner-legal horizontal lay flat engines on the market.

Fitted as standard with a wider ratio gearbox for increased top speed and long-term reliability also complimented with easy starting - coming with both kick and electric start.

Why are our engines different to other sellers' engines?

Other seller engines:
Engines are sold boxed, unopened and unchecked with no adjustments carried out which if left unchecked could cause potential problems and furthermore serious damage.

Our engines:
We carry out a full inspection to ensure all components are present and make all adjustments "Which are always required" to timing and valve clearance settings. We drain the transport oil which is not suitable to use for running your engine.

What does this mean for me?
This means your engine can be fitted straight into your bike with the peace of mind that a professional technician has set it up to run perfectly for its breaking-in period, which is the most important point of the engine life....... just add good quality 10w/40 semi-synthetic motorcycle oil and away you go.

The engine can be used to upgrade the following:
Pit Bikes, Honda Dax, ST, SS, CUB, Monkey, Z50, Mini Trail, Chaly, ATC 70, ATC 90, the list goes on and on!

Comes complete as follows:
-Complete Genuine YX 50cc engine 5 HP
-4 speed manual gearbox - 1 down, 3 up (1-N-2-3-4)
-Removable side cases
-Output sprocket
-12v coil stator fitted as standard should you wish to run lighting.

Complete with:
-Starter motor wire
-Inlet manifold with spacers, gaskets and bolts
-Kick start
-Gear selector lever

These engines are 440mm long, and 280mm wide. The top mounting is 93mm wide with an 8mm bolt hole, Rear mounting hole is 82mm wide with an 8mm hole. They also have the 4 M8 threaded holes on the underside which are 88mm apart left to right and 44mm apart front to back, These are to hole centres.

Please note: All our engines need to go through a braking-in procedure.

Please follow the engine installation guide we include as this will help you in setting up and getting the most from your new engine.

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Here is a message from a happy chappy who purchased one of the Honda clone engines for a near 2000-mile European trip.

"Just thought I'd let you know, I have just completed an 8-day tour of Europe on my Honda Cub fitted with one of your YX 125 4-speed engines. It ran perfectly for the 1,939 miles of the trip. Speeds were mainly between 43-50mph. It is still as quiet as a mouse and used no oil (I did have an oil cooler fitted). Countries visited, in order, were:- France, Belgium, Luxembourg, France, Germany, Czech Republic, Germany, Austria, Germany and finally France. Was I worried it wouldn't make it? YES. Am I worried now? No. Another YX engine also made it, one of your 150 manual clutch jobbies. Thanks for a great engine, Bogger"

 

IMPORTANT INFORMATION:

Before you use it, please note the following:

The engine valve clearances have been set and transport oil drained by us before dispatch.
The recommended replacement engine oil is Putoline DX4 10W/40 from our store.

Engine Data:
Oil Level – most pit bike engines hold 700 – 750ml of oil, please ensure the engine is level and flat with the bike not resting on the side stand. If using a dipstick then remove, clean and push back in without screwing in, then remove to look at the oil level reading. If using a sight glass, then the oil level must be around halfway.
Valve Clearances – all 2 valve new engines use the same valve clearance settings (engine cold) Inlet = 0.10mm & Exhaust = 0.15mm.

If you are unsure of how to time your engine correctly and how to set your valve clearances, then please follow a YouTube tutorial.

Installation:
We would always recommend installation by a professional qualified person.
Please ensure the engine breather pipe is fitted to the crankcase and the rubber blanking plug removed (if fitted). Ensure there are no kinks in the breather hose and check you can feel the pressure escaping when the engine is running.

Oil Coolers:
We would always recommend using an oil cooler when possible. Using an oil cooler will keep the engine below 190 degrees, even though it is an air-cooled engine if used under racing conditions then it can become very hot. The cooler will lower the oil temperature which will prolong the component lifespan inside the engine.

Running In Period:
We firstly recommend the engine has a few heat cycles before use, this is where you would start the engine for around 5 minutes and then turn off to cool down completely. This allows the piston to bed in and for you to check for any leaks around your oil cooler lines.
We would then advise about 1-hour use (with breaks) of gentle riding which doesn’t exceed half throttle.
We would then finally advise for an oil change and to check the valve clearances and adjust if needed.

Terms and Conditions

Important Notice:
Our engines are sold strictly for competition and race use only and are built to provide a cost-effective solution for this purpose. These engines are not designed for road use and are not intended for applications outside competition or racing.

Due to the nature of race and competition use, repairs should be expected as part of the standard maintenance process. Buyers should understand that it is unrealistic to assume the engine will not require repairs, even after only short use. If you are not prepared to perform maintenance or repairs, we strongly advise against purchasing this engine.

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Inspection Period
Before starting the engine, you must inspect it thoroughly for visible defects or issues. If you believe there is a manufacturing fault, you must notify us immediately before the engine is used.

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First-Start Inspection Period
To ensure customer satisfaction, we allow buyers a one-time opportunity to start the engine and listen for any potential faults. If a fault is suspected during this initial start, you must stop using the engine immediately and contact us for guidance.
Key conditions of the First-Start Inspection Period:

• The inspection is limited to starting the engine and listening for faults.
• No riding or extended use is permitted during this period.
• If no faults are reported immediately after the first start, the engine is deemed accepted in its delivered condition.
• If a suspected manufacturing defect is present upon first start, contact us to obtain approval for the return. Upon return, the engine will be inspected by us to determine if it is covered under a manufacturing error.
• Any continued use or riding of the engine beyond this point voids the ability to report faults and confirms acceptance

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Acceptance Upon Use
Once the engine has been started and the First-Start Inspection Period has passed without issue, it is considered accepted in its delivered condition. At this point, no returns, exchanges, or refunds will be accepted under any circumstances.

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Racing Disclaimer
These engines are designed for cost-effective race use and are manufactured to Chinese standards. While they meet the basic requirements for competition use, they are not engineered for the extreme wear and tear of professional or long-term racing environments.

By purchasing, buyers accept full responsibility for maintaining and repairing the engine as necessary. Any failure to align expectations with the nature of these engines is at the buyer's risk.

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No Guarantees or Warranties
We do not offer guarantees, warranties, or returns for engines subjected to:

• Competition or race use.
• Installation in road-going motorcycles.
• Improper installation or misuse.

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Items Not Covered Under Any Conditions
Below are examples of items not covered under the first-start defect policy as they typically result from rider misuse or negligence:

• Kickstart gears (caused by excessive kicking and/or incorrect carburettor setup).
• Clutch basket centre gear (caused by excessive kicking and/or incorrect carburettor setup).
• Gearbox output shaft snapped (caused by applying excessive force to the kickstart following a damaged or broken kickstart gear; owner negligence). Contact us for advice if the kickstart is jammed—under no circumstances should it be forced.
• Barrel and piston wear.
• Gearbox dogs (caused by failure to use the clutch correctly).
• Premature valve damage (caused by over-revving).

Repairs and maintenance are a normal part of pit bike engine ownership, and buyers should expect to carry out such work periodically.

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Claims Before Use
If you suspect a manufacturing defect before the engine is started, please contact us to discuss the issue. Most problems can be resolved without the need to return the engine. If a return is authorised:

• The engine must be returned in its original packaging.
• The buyer is responsible for covering all shipping costs.

Engines will be inspected upon return. If no defect is found, return shipping costs will also be the responsibility of the buyer.

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Final Note
These engines are a budget-friendly option for competition use and are built to provide value for their price point. Buyers should align their expectations accordingly. Regular maintenance and repairs are not only common but should be anticipated, especially under racing conditions.

By purchasing, buyers agree to these terms and acknowledge that the engine is provided as is, with no guarantees, warranties, or return options after use.