What is this part called and what’s it do? Engine won’t star

Mr. Sachs Sachs /

Hi everyone,

You know the story, it was working great, then a friend borrows it and returns it not working.

I’ve replaced all of the following parts below and it doesn’t turn over. It has good compression and spark.

Cleaned tank

New gas

Pepcock replaced

Gas line

Gas filter

Rebuilt carb/cleaned carb

Carb starter spray technique tried

Tried to kick it over multiple times down a long steep hill.

1st Picture - This part is rusted and doesn’t work how it use to. It’s some interesting spring that disengages a rod from inside the engine, pretty sure it’s the choke and lets more air into engine when starting. I’m assuming I should replace it but where do I find the part? Thanks for any help

Second and Third picture - Know where I can get this part? Is it the solenoid or coil??? brand Boch

3) how hard it is to un-seize or redo a post one in a moped?

Thanks and any help or advice!

Mr Sachs

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Re: What is this part called and what’s it do? Engine won’t star

1-decompression valve, makes it easier to turn over when starting.

2-ht coil

Re: What is this part called and what’s it do? Engine won’t star

1. Decomp valve that is notorious for leaking. Aaron is correct that it is supposed to make turning the engine over easier. Its really unnecessary on a Sachs. Common on belt driven mopeds. Replace it with a bolt. Seriously, it is only a future problem if you can even find a decent replacement.

2. Bosch ht (high-tension) coil. If you have spark, it's working. That's a quality part that rarely is the culprit.(edited)

Re: What is this part called and what’s it do? Engine won’t star

Richard Eberline /

If its seized rebuild the motor. If the bike doesn't have spark, has a safety circuit in the rear taillight. 6 volt 10 watt or a 6 volt 5 watt bulb. easy test with a 6 volt battery, square style.

Re: What is this part called and what’s it do? Engine won’t star

Give the motor a proper leak down test to eliminate the chance of having a vacuum leak.

Is the spark bright blue, snappy and strong enough to be seen in the shadow of the bike?

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