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Puch Maxi Bing carburetor explained
The Bing carburetor is one of the most common carburetors used on the Puch Maxi. It is simple, reliable, easy to service, and works well on standard and mildly tuned Puch engines. This guide explains the different Bing carburetor sizes for the Puch Maxi, which version fits which setup, and what to check when cleaning, rebuilding, or adjusting your carburetor.
Many original 25 km/h (15 mph) Puch Maxi mopeds used a 10mm Bing carburetor, while many 45 km/h (28 mph) versions used a 12mm Bing carburetor. Some models, mainly outside Europe, were supplied with a 14mm Bing carburetor. The 15mm Bing carburetor was not originally fitted to the Puch Maxi, but it is a popular upgrade because it keeps the classic Bing look while offering more airflow.
Application: Puch Maxi Bing carburetor
The correct Bing carburetor depends on the version of your Puch Maxi and the engine setup. Standard engines usually work best with the original-style sizes, while tuned engines can benefit from a larger 15mm Bing.
| Bing carburetor size | Typical Puch Maxi application | Best use | Important note |
|---|---|---|---|
| 10mm Bing | Many original 25 km/h (15 mph) Puch Maxi mopeds |
Original restricted setup | This size is no longer commonly produced new. |
| 12mm Bing | Many original 45 km/h (28 mph) Puch Maxi mopeds |
Standard riding and original replacement | Good choice for a reliable standard engine. |
| 14mm Bing | Some Puch Maxi models, mainly outside Europe | Mild performance or specific original models | Less common than 12mm and 15mm versions. |
| 15mm Bing | Popular upgrade, not originally supplied on Puch Maxi | More power, better airflow and 70cc street setups | Looks similar to smaller Bing carburetors but has a larger diameter. |
Looking for a replacement or upgrade? View the available Puch carburetor sets at Puchshop.
Back to top10mm, 12mm, 14mm and 15mm Bing carburetors
10mm Bing carburetor
The 10mm Bing carburetor was used on many original 25 km/h (15 mph) Puch Maxi mopeds. It is suitable for restricted standard setups, but it limits airflow and is not the best choice for a tuned engine.
12mm Bing carburetor
The 12mm Bing carburetor was commonly used on 45 km/h (28 mph) Puch Maxi models. It is a strong choice for a standard or lightly improved engine where reliability and easy adjustment are more important than maximum performance.
14mm Bing carburetor
Some Puch Maxi models were delivered with a 14mm Bing carburetor, especially outside Europe. This size sits between the common 12mm standard carburetor and the popular 15mm tuning upgrade.
15mm Bing carburetor
The 15mm Bing carburetor was not originally fitted to the Puch Maxi, but it is one of the most popular upgrades. It keeps the classic Bing look while allowing more airflow. It is often used for more power and can work well with many 70cc cylinder setups.
Puch Maxi Bing carburetor parts overview
A Bing carburetor consists of many small parts. For the carburetor to work correctly, the parts must be clean, complete, and in good condition. Worn or mismatched parts can cause poor starting, leaking, flooding, bad throttle response, or an incorrect fuel mixture.
When rebuilding an old Bing carburetor, pay close attention to the manifold connection. If the carburetor has been removed and tightened many times, cracks can appear around the connection point. A cracked or badly worn carburetor body can cause air leaks and poor running.
Exploded view of a Bing carburetor for the Puch Maxi.
The schematic drawing shows the main Bing carburetor parts. Some of the most important parts to check during cleaning or rebuilding are listed below.
| Number in drawing | Part | Function | What to check |
|---|---|---|---|
| 8 | Small retaining ring | Helps hold the throttle needle clip in position. | Make sure it is installed above the needle clip so the needle cannot move upward unexpectedly. |
| 9 | Throttle needle | Controls fuel delivery in the mid-throttle range. | Check for wear and make sure it matches the correct nozzle tube. |
| 10 | Needle clip | Sets the needle height inside the throttle slide. | Clip position changes mid-range fuel mixture. |
| 13 | Nozzle tube | Works together with the throttle needle to meter fuel. | Size must match the needle. The Bing repair kit uses a 212 nozzle tube with the matching needle. |
| 14 | Main jet | Main fuel adjustment for higher throttle openings. | Jet size depends on the complete engine setup. |
| 17 | Float | Controls the fuel level in the float chamber. | Float height must be correct to prevent fuel starvation or leaking. |
| 27 | Idle adjustment screw | Adjusts idle speed by changing the throttle slide position. | Use as a starting point, then adjust warm idle after the engine runs. |
Interactive Bing Tuning Simulator
Twist the throttle below to see how the specific parts of your Bing carburetor hand off fuel-metering responsibility as throttle opening and engine load increase.
Active Bing Components
Constant Systems
Throttle needle and nozzle tube on a Bing carburetor
The throttle needle and nozzle tube must match each other. This is one of the most important details when rebuilding a Bing carburetor.
Nozzle tube: number 13 in the drawing
The nozzle tube is available in different sizes. The correct size depends on the throttle needle that runs inside it. Older original Bing carburetors may have different needle and nozzle tube combinations.
When replacing the original nozzle tube, first check the size of the old one. The size is usually engraved on the part. The nozzle tube supplied in the Bing repair kit is a 212 nozzle tube, and it matches the needle included in that kit.
Throttle needle and needle clip: numbers 9 and 10
The throttle needle sits inside the throttle slide. The needle clip can be installed in different slots, which changes the height of the needle. This affects the fine adjustment of fuel delivery in the mid-throttle range.
| Needle position | Effect | What it means |
|---|---|---|
| Needle sits higher | More fuel in the mid-range | Richer mid-throttle mixture. |
| Needle sits lower | Less fuel in the mid-range | Leaner mid-throttle mixture. |
If you order a new Bing throttle needle, it is officially intended to be used with a 212 nozzle tube. New replacement needles are supplied in one size.
Float and fuel level adjustment
The float controls the fuel level inside the float chamber. When the float chamber fills with fuel, the float should shut off the fuel supply at the correct height.
What happens if the float is wrong?
| Float problem | What happens | Typical symptom |
|---|---|---|
| Float too low | Fuel supply shuts off too early. | Float chamber does not fill enough, and the engine may run out of fuel. |
| Float too high | Fuel supply does not shut off in time. | Carburetor can overflow and leak fuel. |
| Float height correct | Fuel level stays stable. | Cleaner running and more reliable fuel supply. |
Main jet adjustment on a Puch Maxi Bing carburetor
Number 14 in the drawing is the main jet. The main jet is used for the main fuel adjustment of the moped. A larger main jet allows more fuel into the engine. A smaller main jet allows less fuel.
The correct main jet size depends completely on the setup of your Puch Maxi, including the cylinder, carburetor size, air filter, exhaust, and intake.
| Jetting situation | Possible result | What to do |
|---|---|---|
| Main jet too small | Engine can run lean and overheat. | Use a larger jet and test carefully. |
| Main jet too large | Engine can run rich, four-stroke, smoke heavily, or lose power. | Reduce jet size step by step after testing. |
| Main jet correct | Clean throttle response and safe full-throttle running. | Confirm with test rides and spark plug reading. |
Use the correct Puch main jets and adjust in small steps. Always start safely rich when testing a new setup.
Back to topIdle screw adjustment on a Bing carburetor
Number 27 in the drawing is the idle adjustment screw. This screw adjusts the idle speed by moving the throttle slide position.
- Turning the screw in raises the throttle slide and increases idle speed.
- Turning the screw out lowers the throttle slide and reduces idle speed.
- A common starting point is to turn the screw fully in and then back it out about 1.5 turns.
- Final idle adjustment should be done when the engine is warm.
Puch Maxi Bing carburetor rebuild checklist
If your original Bing carburetor is worn, dirty, leaking, or difficult to tune, rebuilding it with fresh parts is often the best solution. If the carburetor body is badly worn or cracked, replacing the complete carburetor may be smarter.
When should you replace the carburetor instead of rebuilding it?
- The carburetor body is cracked.
- The manifold connection is damaged or leaking.
- The throttle slide bore is heavily worn.
- The carburetor has been overtightened many times.
- The engine remains impossible to tune after cleaning and replacing wear parts.
Common Puch Maxi Bing carburetor problems
Many running problems on a Puch Maxi come from the carburetor. Dirt, incorrect float height, wrong jetting, worn needles, air leaks, or missing parts can all affect how the engine runs.
| Problem | Possible cause | What to check |
|---|---|---|
| Carburetor leaks fuel | Float too high, dirty float needle, worn float needle, or incorrect float setting. | Float, float needle, fuel shutoff point, float chamber. |
| Engine runs out of fuel | Float too low or restricted fuel flow. | Float height, fuel tap, fuel hose, filter, float chamber. |
| Poor mid-throttle running | Wrong needle position or mismatched needle and nozzle tube. | Throttle needle, needle clip, nozzle tube size. |
| Poor full-throttle running | Wrong main jet size. | Main jet, spark plug colour, air filter, exhaust setup. |
| Difficult idle adjustment | Dirty carburetor, air leak, worn slide, or incorrect idle screw setting. | Idle screw, throttle slide, intake gasket, carburetor cleanliness. |
| Engine is hard to tune after rebuild | Missing small part, incorrect assembly, worn carburetor body, or wrong needle/nozzle tube combination. | Exploded drawing, needle, nozzle tube, retaining ring, gasket surfaces. |
Conclusion: Bing carburetors for the Puch Maxi
The Bing carburetor is a reliable and practical choice for the Puch Maxi. A 10mm or 12mm Bing suits original-style setups, while a 15mm Bing is a popular upgrade for riders who want more power while keeping the classic Bing look and simple adjustment.
When cleaning or rebuilding a Bing carburetor, pay special attention to the throttle needle, nozzle tube, float level, main jet, idle screw, and manifold connection. Clean parts, correct assembly, and careful adjustment make the difference between a Puch Maxi that is difficult to tune and one that starts, idles, and accelerates properly.
Back to topBing carburetor options for Puch Maxi
Need the right Bing setup? Puchshop offers original Bing carburetors, replica Bing carburetors, different sizes, and rebuild parts for Puch Maxi. Use the options below as a practical starting point, then check the full Bing selection if you need a different size, kit, or intake combination.
Bing SRE 15mm carburetor Puch Maxi original (1/15/46A)
Model number: 20042Best choice when you want the classic Bing look, original quality, and more airflow for mild tuning or many 70cc street setups.
Bing SRE 12mm carburetor Puch Maxi replica
Model number: 20123Practical replica option for many standard Puch Maxi setups where easy fitment and original-style riding matter most.
Bing SRE 14mm carburetor Puch Maxi replica
Model number: 20116Good middle step between a standard 12mm Bing and a 15mm upgrade when you want a little more breathing room.
Bing SRE 17mm carburetor Puch Maxi replica (3.5 mm jet)
Model number: 811346For riders moving beyond a mild setup. Check intake, air filter, exhaust, and jetting carefully before tuning.
Bing SRE 12–15mm carburetor repair / rebuild kit Puch Maxi
Model number: 20140Useful when your original Bing body is still good, but the wear parts, seals, needle, or nozzle tube need refreshing.
FAQ: Puch Maxi Bing carburetor
Which Bing carburetor was originally fitted to a Puch Maxi?
Many 25 km/h (15 mph) Puch Maxi mopeds were originally fitted with a 10mm Bing carburetor, while many 45 km/h (28 mph) versions used a 12mm Bing carburetor. Some models, especially outside Europe, used a 14mm Bing.
Is a 15mm Bing original on a Puch Maxi?
No. The 15mm Bing was not originally supplied on the Puch Maxi, but it is a popular upgrade because it looks similar to the original Bing carburetor and gives more airflow.
Is a 15mm Bing good for a 70cc Puch Maxi?
Yes. A 15mm Bing is often a good match for a 70cc Puch Maxi street setup, especially when the intake, exhaust, and jetting are also adjusted correctly.
What does the nozzle tube do in a Bing carburetor?
The nozzle tube works together with the throttle needle to control fuel delivery in the mid-throttle range. The needle and nozzle tube must match each other for correct tuning.
What nozzle tube is included in the Bing repair kit?
The nozzle tube included in the Bing repair kit is a 212 nozzle tube. It matches the needle supplied with the repair kit.
How do I know if the float height is wrong?
If the float is too low, the float chamber may not fill enough and the engine can run out of fuel. If the float is too high, the carburetor can overflow and leak fuel.
What does the main jet do?
The main jet controls the main fuel supply, especially at higher throttle openings. A larger main jet gives more fuel, while a smaller main jet gives less fuel.
When should I replace my Bing carburetor instead of rebuilding it?
Replace the carburetor if the body is cracked, the manifold connection is damaged, the throttle slide bore is badly worn, or the carburetor remains difficult to tune after cleaning and replacing wear parts.
