Myron's Mopeds

Welcome, Carb Elbows: Long and Short         Scroll Down to See Topic 

Above, left is the long carb elbow, used on Maxi models, also with the black choke extension. Right, is the short carb elbow used on Magnum type models. The current aftermarket “Puch” throttle cables are made for the short carb elbow. They idle way fast if used with the long elbow, because the slide is not allowed to go fully down to idle. Myrons sells a long elbow throttle cable, for Puch Maxi, made from a modified “Puch” throttle cable. The wire needs to be about 12mm longer. The long elbow comes on Maxi type sheet metal frame models. The short elbow comes on Magnum type tube frames, such as Sears Free Spirit or JC Penney Pinto. The short elbow is so your foot does not hit it when you get on and off the bike. See the exploded view diagram below. Other Bing moped (under 15mm venturi) carburetors are the Sachs Bing, Kreidler Bing, Solo Bing, Tomos Encarwi, Batavus Encarwi, Trac Encarwi. Much bigger Bing carburetors are also on BMW, KTM, Penton, Sachs, Maico, DKW motorcycles, all made in or near Germany.

Exploded View and Parts Names

Above, Puch Bing carburetor exploded view with Myrons names and notes. The “needle jet” is also known as the “jet holder”. 

2. Carburetor Service Info Sheet

Below, the choke slide and throttle slide must be installed simultaneously. It is difficult. The throttle slide has a slot that must line up with a prong in the carb body. The top of the choke slide slides onto a deep wide notch at the bottom of the choke rod, so moving the choke rod moves the choke slide. It often gets left out or disconnected. When the choke slide is disconnected from the choke rod, the choke will be “on”, blocking off the air supply, whenever the throttle slide is down or closed. Normally when a Puch is given full throttle, the choke slide and rod are lifted all the way up until it clicks. The click is the choke rod clip #24 settling into the clip groove near the middle of the choke rod #23. When the throttle cable is not adjusted tight enough, the choke is not lifted all the way off, and it does not click until you manually reach down and pull up on the choke rod. When the throttle cable is adjusted too tight, the engine races and does not idle slow, even with the idle screw loosened all the way. See also General Carburetor Service and Jetting for how to clean and adjust carbs in general. 

3. Bing Jet Sizes Chart

Below is a graph of Bing 3.5mm jet size versus jet number. It shows how the aftermarket jets are a different size than the originals, how to tell what kind of a jet it is, and how to tell what size a jet actually is or should be, using a set of “jet drills” size 80 to 61 (or a set of machinists precision hole gauges 0.011 to 0.040 inch in 0.001 increments).

4. Puch Carburetor Configurations

Below is a list of 27 different Bing Puch carburetors. There are just two “carb bodies”,  12 and 14mm. But they can have different jets, needle jets, throttle slides, and throttle needles (different from float needle!).  Use the chart below to configure (change the settings) a carburetor for a particular model, as long as it’s original and stock. For example, you have a 1977 Puch Maxi with no carburetor. You have a 1980 Murray carburetor that looks identical. From the chart they are both 14mm venturi, but the jet needs to be size 64 not 62, the slide #24 not 51, the needle 1 notch not 2, and the needle jet size 2.22 not 2.12A. Change those four things, and change the stamped on number from 1/14/166 to 1/14/160, and you will have the original specification carburetor. Or if you have a scrambled pile of carburetors and loose pieces, you can make any original configuration carburetor from the chart.

There are always some (sometimes lots of) little things that make life difficult. Old engines with compression and/or air leaks will need bigger than original jets. Old engines with clogged exhausts will need smaller than original jets. Engines with the original air box removed or modified will need bigger jets. Engines with performance exhausts will need bigger jets. Engines with big bore cylinder kits will need much bigger jets. This chart says what jet your bike had when it was brand new, not necessarily what jet is correct for it in it’s current state.  

5. Bing Float Needles 

All “Bing Puch Carbs” have the slotted float type float needle with a rubber cone tip, except for some of the Sears Free Spirit 1/14/163  and 1/14/164 carbs, which have a Sachs Bing type float needle that does not lock into a slot in the float and has a metal cone tip.

6. What part controls mixture depends on how much throttle opening