Sachs 503 reed valve engine limited?

dmitriy /

Mar 18, 2009 05:12PM

I recently got a 1974 Hercules 2 speed manual moped with a Sachs 503 reed valve engine. The previous owner said he was relatively certain that the engine has some sort of a limit on it. As it is now - the moped reaches only around 20mph, and it reaches this top speed very fast - making it feel like it should definitely be able to go faster.

If there is a limit, and there is a way to take it off and make the moped faster, I would really want to do it.

I am a complete Moped noob as far as mechanics go (to the point of barely knowing how a carborator works (and all that i got from wikipedia) - but I really want to learn everything.

I tried looking as much as I could about Sachs engines, but with my limited knowledge I don't think I even know what exactly to look up.

Would anyone be able to throw some tips, guidances, links to guides, etc. Perhaps ask me questions on more information about the moped and engine (and how to find it, since there is no paperwork with it.)

Much appreciated,

-dm

Re: Sachs 503 reed valve engine limited?

nerdzilla NoPeds :( /

nerdy

Mar 19, 2009 01:25PM

rear sprocket size is crucial. my stock had what looked to be a large ass dinner plate. downsize as much as possible. gear ratio=speed, but you loose takeoff. thats a cheap solution. step 2. carberator and expansion chamber. your restricted (most likely stock) setup will only go so fast. bigger chamber=more juice. but you have to adjust your carb accordingly with more gas=bigger jets. so far ive doubled and then some on my speed with sprocket, jet and expansion chamber. sach has very few aftrmkt chambers, youll have to mod one up yourself. not too hard tho.

Re: Sachs 503 reed valve engine limited?

peter /

Go to branch

peter

Mar 19, 2009 02:36PM

shift into 2nd gear!

Re: Sachs 503 reed valve engine limited?

dmitriy /

pessimizor OP

Mar 19, 2009 05:08PM

haha - thanks pete

Thank you nerdy.

The gear ratio solution indeed seems like the simplest cheapest solution - since the takeoff currently is definitely more than plentiful (on the 1st gear). I will read up on everything and see what I can do.

Re: Sachs 503 reed valve engine limited?

VB_Pat /

vbskimer

Mar 19, 2009 06:51PM

Let's see a pic of this rare machine!

Re: Sachs 503 reed valve engine limited?

dmitriy /

pessimizor OP

Mar 19, 2009 08:56PM

I took a few quick ones just to show it. Plan to clean it up, and take a bunch of nice ones on a sunnier day.

moped:

manual transmission!

tag - I'm pretty sure the previous owner said it's an MP-2, but the model type here is some weird long string

engine:

engine tag:

Re: Sachs 503 reed valve engine limited?

nerdzilla NoPeds :( /

nerdy

Mar 19, 2009 09:05PM

wowee we wa. thats a pretty one.

Re: Sachs 503 reed valve engine limited?

andrewhed /

andrewhed

Mar 20, 2009 01:49AM

how many teeth are on the front and rear sproket.

also that has a 10mm carb....

Re: Sachs 503 reed valve engine limited?

nerdzilla NoPeds :( /

nerdy

Mar 21, 2009 05:45PM

lookin @ the pics, yr rear sprocket seems of a good size. i think your issues are in your expansion chamber and carb. make sure they are clean, then see what your performance is. if yr carb is a 10mm.... yr gonna have to upsize. chamber too.

MOPED ARMY

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