This is my first motor-vehicle ever, a Simson s50 from 1976.

Things seem to be running fine, but there are two problems I need to figure out:

1) The engine dies unless rev'ed constantly - eg at a light. I assume this is simply an adjustment of the idle screw?

2) Once the engine dies, it will not kick-start again. This is what is most confusing to me as it will kick-start fine after a rest, eg - first thing in the morning and again later in the evening. However, it will absolutely refuse to start after stalling say at a red light etc... The only chance of getting the engine running again is a push-start. Is there any reason for this?

I've taken it in to a shop and all they did was change the spark plug. It still has these above problems even after three visits to the shop!

Any tips much appreciated, as I am a newbie to motors!

My Simson S50

  • When the engine dies, have a look at the spark plug (careful it will be hot) if the tip is soaked/black then the engine is running too rich.
    – Mauro
    Aug 8, 2012 at 14:14

1 Answer 1


Check the compression. If something is causing a loss of compression, like worn piston rings, then that could be the reason for all those problems. Push starts creates higher pressure in the cylinder because it moves the piston faster than a kick start. Also, it could start cold but not warm due to the temp of the air being brought into the cylinder. When an engine is hot it will bring in heated air which is less dense, as to when it is cold the air wont be heated up by the engine and be more dense, leading to greater compression.

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