1975 Puch Maxi rebuilt but has very low speed/acceleration issues

Meghan M /
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Hello all,

This is my first moped and rebuild experience and while I do not have any prior mechanical experience I read many of the manuals, guides, and forum posts which has helped me get my bike running again.

However I am experiencing a few issues that I hope you guys can help me with. Here is the situation:


- 1975 Puch Maxi Deluxe (Bombardier version)

- E50 engine re-built and cleaned with new seals, circlips, and gaskets

- Stock exhaust that has been cleaned however could not get baffle out to clean as it is stuck

- New stock air filter box

- Original Bing 14mm Carb rebuilt and cleaned including:

o New banjo bolt and gaskets

o new plastic float, float needle and float pin that is currently adjusted to be parallel to the float bowl rim

o new atomizer (2.20) and jet (64) that matches stock sizes on the bike

o needle is set at 2nd position from top

- Points are not new but were cleaned and gap set correctly

- Timing adjusted to get as close as possible to 18mm before TDC (might be off a little as I do not have a timing light but I cannot position the stator further to get closer to TDC)

- New petcock, inline fuel filter and fuel line.

- Condenser looks okay (original soldered version)

- Compression is 100 psi on cold engine

- Bike currently hardwired for spark only as one of the other electrical wires was preventing spark

- New spark plug – NGK B6HS


- Bike will start on first kick most times and will idle only with choke in up position. Will not start with choke down.

- If you push the choke down while riding, the engine stops.

- Seems to run similarly with or without stock airbox attached but if you cover the airbox hole to the carb it kills the engine.

- Turning the throttle does not seem to increase the speed at all or very little. WOT causes engine to die most times. Very slow.

- Did a plug chop and it came out covered in matte black carbon, was dry and not wet – too rich?


- Where should I start in order to fix the acceleration issue?

- How can you tell a weak spark from a strong one? I can see a blue spark when I hold it against the cylinder and pedal but not sure if it’s a strong spark.

- Should the points be replaced if there is low power? The condenser?

- I checked for air leaks around the Carb while the engine was running and didn’t find any but not sure if my compression is good at 100 psi?

- When I put the piston back together, the two little clips that hold it in on either side were facing different ways, is that a problem?

Thanks in advance for your help!

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