Sachs G4 505 / 1D engine rebuild

i have a Sachs 505 / 1D. I have had it since it was new way back in the stone age. The engine has only 1681 miles on it. Back in the 90s my Father used it for awhile and had it tuned up and running. it has been sitting for 15 years in storage now the engine is locked up . I pulled the trans cover off the clutch seems in good shape .The pedals turn freely but when I pull the clutch handle (decompression) it didn't budge an inch.So I pulled the spark plug and filled the head with WD40 and let it sit. Still nothing! The next step was to remove the head. With a little effort it came off.Cylinder inside is in really nice condition can still see hoaning marks from the factory. Piston rings fell apart in my hand like dry crackers. I find out the crank bearings are jamed and the piston needle cage is really stiff. I sprayed the the side of the motor let it sit then rocked the flywheel back and forth until the motor turned free. now I need some advice and help before I open the motor . If it is just the crank bearings and piston parts do I have to touch the rest of the gear drive ( it all seems to turn freely with no grinding or skipping)

Re: Sachs G4 505 / 1D engine rebuild

As the old adage goes: “do it once, do it right.” If you’re in the motor already you might as well do a rebuild, not much more work or cash, I wouldn’t say rebuild the whole pedal system but replace what you can(gaskets and bearings). Mopeds aren’t reliable when relatively new, even less reliable years later with crusty, rusty parts.

Re: Sachs G4 505 / 1D engine rebuild

thank you for your input Aaron . I will go a little deeper in the motor to see how bad it really is

Re: Sachs G4 505 / 1D engine rebuild

Is the motor worth rebuilding The bike is not in bad shape apart from brakes and rear wheel bearings

Re: Sachs G4 505 / 1D engine rebuild

> Len Shannon Wrote:

> -------------------------------------------------------

> Is the motor worth rebuilding The bike is not in bad shape apart from

> brakes and rear wheel bearings

The question is is it worth it to you?

Re: Sachs G4 505 / 1D engine rebuild

You have A point. But i was thinking of the resale end . The Sachs G4 505 / d1 is a rare bird this corner of the world.

Re: Sachs G4 505 / 1D engine rebuild

Ha . About the only value it has is the fact that you've owned it since new . If you could sell that , you might get a little money . But , ownership adds no value unless you're a stupidly famous person that left a good impression and then it maybe only be negligible with a very limited market .

Shy of any of that^ , maybe a few hundred bucks , if you're fortunate .

Re: Sachs G4 505 / 1D engine rebuild

rebuilding that motor is easy, can be done in like 2 hours even as a first timer.

Use an impact drill to pull the clutch and stator nuts (or a rope or some other piston stop to keep the crank from turning) flywheel puller is the only special tool you need. buncha 5mm allen bolts on bottom, pull it all out slide off the seals and pop off the bearings, replace it all. shits are cheap and easy to come by. goop it and reassemble bam bam bam. I just rebuilt 2 sachs motors in my basement last week, doing a third maybe tonight.

Re: Sachs G4 505 / 1D engine rebuild

> Born to be WillD Wrote:

> -------------------------------------------------------

> rebuilding that motor is easy, can be done in like 2 hours even as a

> first timer.

>

> Use an impact drill to pull the clutch and stator nuts (or a rope or

> some other piston stop to keep the crank from turning) flywheel puller

> is the only special tool you need. buncha 5mm allen bolts on bottom,

> pull it all out slide off the seals and pop off the bearings, replace it

> all. shits are cheap and easy to come by. goop it and reassemble bam bam

> bam. I just rebuilt 2 sachs motors in my basement last week, doing a

> third maybe tonight.

I'd argue a bearing puller is also a special tool you'd need.

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