Sachs... how fast, etc.

Justin /

May 25, 2001 11:43AM

Hello world...

I've a 1977 sachs hercules in pretty good condition. I've had difficulty finding info on this beast. A couple questions:

1 - Does anyone know what voltage the lights should run at? I put a couple 6v lights in the back, but I seem to only be able to get the headlights to run brightly if the back lights are off. It's kind of amusing to ride at night... "Front or rear lights?"

2 - How fast should this beast run? It seems healthy- I get a surprising amount of low end. Accelerates up hills as fast as I could ask for, but the thing peaks out at about 20 mph. Thing is, when I get there, the engine just doesn't hum as beautifully as it does at slightly lower speeds. Is it possible I've got a limiter on it somewhere? Is that just how fast these things run?

Likely I'll put on a different sprocket to trade some low end for high end. Anybody tried welding the new sprocket onto the old one so it is relatively easy to switch the gearing in different conditions?

Thanks!

-Justin

Re: Sachs... how fast, etc.

Ron Brown /

May 25, 2001 12:48PM

Justin,

It sounds like you may be 4-cycling when you reach 20 mph. Search this forum using every varyiation of 4-cycle, "air cleaner", or "jet" and see what you get. This problem has been covered in great detail.

Also read Fred's "How to fix your moped" on this board.

Ron

Re: Sachs... how fast, etc.

Peter /

May 25, 2001 02:55PM

If you weld a another sprocket onto the existing one, you'll have two

problems:

1) if you don't get it pretty well centered on the existing one, you'll get

some interesting vibrations that you may not enjoy

2) worse: the drive chain should run straight back from the engine drive

sprocket to the wheel sprocket (technically, the chain should stay in one

plane). Your "new" welded-on sprocket will be laterally offset from the existing one, which means that the chain will not run straight back. This will put huge stresses on the chain links. I wouldn't be surprised if the chain broke catastrophically "at speed". You don't want bits of chain flying around your leg, do you?

I wouldn't do this.

multi-sprocket

SteelToad /

May 25, 2001 03:09PM

That made me think of something. What if you welded the two sprockets

together with a spacer inbetween that way the sprocket sould stay in-line with

the back wheel, and you could just flip it over on the shaft to switch over to

the different gear, still staying in-line. Of course there is the difference in the

chain length to contend with

Re: multi-sprocket

Ron Brown /

May 25, 2001 03:17PM

Next time you see a Vincent Black Shadow, check the rear sprocket.

An extra split link takes care of the length problem.

Ron

Re: Sachs... how fast, etc.

daveb /

May 25, 2001 06:06PM

I have a friend that has a Hercules that only went 20. If yours is the same there are a number of things holding you back.

1 smaller carb. When you pull off the top of the carb there may be a needle at the bottom of the carb cylinder like in a Puch and you probably have a 52 jet. The larger carb doesn

Re: multi-sprocket

Justin /

May 25, 2001 07:54PM

Hrmm... The chain being laterally offset sounds like a big problem. Bikes get away with this I guess because they have much smaller tensions on the chain? Something I COULD do would be to weld sprockets (with the spacer to keep them straight) onto both the back and front, and change them both at the same time. The chain would then avoid those nasty tensions in the wrong directions. But, uhh... This is sounding insane, and I'm not gonna do it.

Re: Sachs... how fast, etc.

Justin /

May 25, 2001 08:04PM

I'm pretty sure I'm not four stroking- it's not a dramatic change in the engine, it just looses that amazing growl it has at lower speeds. It's wierd to have the moped shoot off from a stop with so much acceleration, and then suddenly at around 20mph stop going faster.

Hrmm.... All these things sound more like 'modifications' then 'tune ups'... Changing the piston/cylinder is beyond me, and I suppose changing the carb/manifold will cause my gas mileage to plummet, the bike to wear out quicker, etc? Are there any mods aside from the sprocket that won't hurt the gas mileage too much? I've been looking around at bi-turbo exhausts, and I can't seem to understand how changing the exhaust will increase performance.

Still it would be nice to get to 30. How do you people deal with cars? I've only owned a moped for a couple days now, but sweet jesus, I'm not used to these huge metal boxes hurling past me going 10-20 mph faster than me.

Actually yesterday a -biker- passed me. He hung back for a while because he didn't want to bring great shame upon me, but then he peddled past, and I rather wanted to kill myself.

Re: Sachs... how fast, etc.

Ron Brown /

May 25, 2001 08:44PM

Justin,

Read Fred's "how to fix your moped regarding exhaust port and muffler cleaning etc.

I sounds like something is limiting the amount of mixture flowing throug the motor.

Ron

Re: Sachs... how fast, etc.

Jamie Leonard /

May 26, 2001 12:50AM

Actually a biturbo exhaust can make a big difference - not sure of all the mechanics (I know it allows greater airflow, probably helps the engine in much the same way a turbocharger does, allowing more air and more power because of it)

On my tomos I just added this and my first reaction trying it out was basically "holy CRAP" - lot of difference in the top end and in acceleration.

(easily added 20-30kph to my top speed) Probably in terms of mph you'd see at least 5-10? (am guessing mind you on that.. could be off)

As a side benefit mine sounds a heck of a lot beefier - has a bit of a throaty roar to it now (lots louder admittedly... but hey, I like that :)

Jamie

Re: Sachs... how fast, etc.

don-ohio /

May 26, 2001 11:42AM

Hi! It's probably what Ron says about the 4-cycling,but one thing is for sure.You NEED a shop manual for this model.Contact `MOPEDWAREHOUSE' and order one NOW. This eliminates guesswork about your voltage and amperage that you expect it to put out.And don't ride that bike at night for heaven's sake with no rear lights! Fix it or buy a bicycle generator for your headlight or do something.You can be run over quite easily without taillights.BYE! Oh,and any parts you need ,call HANDY BIKES (614-299-0550)

Re: Sachs... how fast, etc.

Hellcat Carrie /

May 26, 2001 04:45PM

Buy the Herc, if it's in decent condition; several people in the moped army own them, and they seem to be very reliable and take all sorts of abuse. I personally rank Puch and Sachs together as the best-designed mopeds. Granted, I OWN these brands, but I will say that I am EXTREMELY happy with my Sachs.

MOPED ARMY

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