Which Carburetor Does My Puch Need?

Complete Guide for 50cc, 70cc and 74cc Engines

Choosing the correct carburetor for your Puch is one of the most important decisions for performance, throttle response, and engine reliability. Whether you ride a standard 50cc Puch or a tuned 70cc or 74cc setup, the right carburetor size ensures smooth acceleration, proper fuel mixture, and long engine life.

In this complete Puch carburetor guide, you will learn:

• Which carburetor works best for 50cc, 70cc, and 74cc engines
• The difference between Bing, Dellorto, and Polini carburetors
• When to use a larger carburetor
• How to tune your carburetor for maximum performance

How a Puch Carburetor Works

A carburetor mixes air and fuel into a combustible mixture for your engine. For optimal combustion, the ideal ratio is approximately 1 part fuel to 14 parts air.

Inside the carburetor

• Air flows through a venturi, increasing speed and lowering pressure
• This pressure difference draws fuel into the airflow
• The throttle slide controls airflow and engine power
• The main jet, needle, and idle jet regulate fuel delivery across throttle positions

A correctly functioning carburetor ensures consistent performance across all riding conditions.

Why Carburetor Size Matters on a Puch

Carburetor size must match your cylinder, intake manifold, and exhaust setup. A larger carburetor does not automatically increase power.

If the carburetor is too large

• Throttle response becomes weak
• Jetting becomes difficult
• Fuel consumption increases

If the carburetor is correctly sized

• Acceleration improves
• Fuel efficiency stays stable
• Engine reliability increases

Most Puch engines perform best with a carburetor between 12mm and 17.5mm.

Quick Overview: Which Carburetor for a Puch

• Standard 50cc: 12mm or 15mm Bing
• Fast 50cc: 15mm Bing or 17.5mm Dellorto
• 70cc: 15mm Bing or 17.5mm Dellorto PHBG
• 74cc: 17.5mm, 19mm, or 21mm (only with modified setup)

The best carburetor always matches the full engine setup.

Which Carburetor for a Standard 50cc Puch

A standard 50cc Puch engine runs best with a Bing carburetor.

• 12mm Bing: Reliable and fuel efficient
• 15mm Bing: Better acceleration and throttle response

The 15mm Bing is one of the best upgrades for a stock Puch because it improves performance without making tuning difficult.

Which Carburetor for a Fast 50cc Puch

A performance 50cc cylinder requires more airflow.

• 15mm Bing: Best for most street setups
• 17.5mm Dellorto: Works when intake and exhaust are upgraded

Correct jetting is more important than carburetor size. A well tuned smaller carburetor often outperforms a poorly tuned larger one.

Which Carburetor for a 70cc Puch

A 70cc Puch engine needs more airflow but still requires balance.

• 15mm Bing: Excellent for street riding
• 17.5mm Dellorto PHBG: Ideal for performance setups

Larger carburetors such as 19mm or 21mm only work properly with

• Reed valve intake
• Modified crankcases
• Tuned exhaust

Which Carburetor for a 74cc Puch

A 74cc Puch engine can benefit from a larger carburetor, depending on setup.

• 17.5mm: Good for mild builds
• 19mm or 21mm: Suitable for high performance engines

Popular choices include

• Dellorto PHBG carburetors
• Polini CP carburetors

When Does a Big Carburetor Work on a Puch?

A large carburetor only works when the engine can handle increased airflow.

You need

• Reed valve system
• Enlarged intake manifold
• Modified crankcases
• Performance exhaust
• Correct ignition timing

Without these upgrades, a large carburetor reduces performance instead of improving it.

Bing vs Dellorto vs Polini Carburetors

Bing carburetors

• Best for standard and street engines
• Easy to tune
• Reliable and consistent

Dellorto carburetors

• More tuning options
• Better for performance engines
• Widely used in racing

Polini CP carburetors

• Compact design
• Strong performance
• Ideal for race setups

For most riders, the 15mm Bing carburetor remains the best all round choice.

Carburetor Tuning for a Puch Engine

Correct carburetor tuning determines engine performance and reliability.

Follow this process

1. Start with the correct main jet
2. Check spark plug color after a test ride
3. Fine tune needle position and idle jet
4. Adjust the air screw

Key components

• Main jet: Controls fuel at full throttle
• Needle: Controls mid range throttle
• Idle jet: Controls low speed operation
• Float height: Maintains fuel level

A properly tuned carburetor ensures smooth acceleration and prevents engine damage.

Common Problems: Flooding and Lean Mixture

Flooding

• Too much fuel in the mixture
• Engine struggles to start
• Spark plug becomes wet

Lean mixture

• Not enough fuel
• Engine overheats
• Risk of engine damage

Always adjust carefully and test after each change.

Conclusion: Which Carburetor Should You Choose?

The correct carburetor for your Puch depends on your engine setup.

• Most street setups perform best with a 15mm Bing or 17.5mm Dellorto
• Larger carburetors only work on modified or race engines
• Correct tuning is more important than size

Choose the right carburetor, install the correct jets, and tune carefully for the best results.

FAQ: Which Carburetor for a Puch

Can I use a 21mm carburetor on a 50cc Puch?

Only if the engine is heavily modified with a reed valve.

Is a 15mm Bing good for a 70cc Puch?

Yes, it works very well for most street setups.

What is the biggest carburetor for a normal 70cc Puch?

A 17.5mm carburetor is usually the practical maximum.

Does a bigger carburetor make more power?

Only if the engine setup supports more airflow.

When do I need a 19mm or 21mm carburetor?

For race engines with upgraded intake and exhaust systems.