Sachs 504/1A Engine - Piston Seized

Hi,

I'm new here. I've had a Solex 4600 for a few years now and recently bought a cheapo Sachs Westlake with a seized piston. I'm new to working on the bikes, and figured I'd start a project bike. It'll take a lot of work and learning on my part but I've got time. It's missing some parts (speedo, plastic side covers and floorboard) and needs some other TLC.

Anyway, it has the 1 piece jug cylinder and I'm trying to free the piston - right now it's filled with PB Blaster and soaking.

I was wondering if anyone had any other tips on how to free up the seized piston in a jug cylinder. Also, any tips on the best way to pry off the ignition cover?

Thanks!

Re: Sachs 504/1A Engine - Piston Seized

Add some heat into the mix after you drain the pb fluid. You could also just plan on replacing your crank. I am not too familiar with the 505 engines but you should be able to find a new one. If you can find a new crank you could just cut the old one off at the con rod and the will allow you to remove the jug from the rest of the engine. Or even just split the cases and remove the crank without cutting.

Just my first thoughts if the jug is un willing to come loose from the piston. Heat before destroying though.

Re: Sachs 504/1A Engine - Piston Seized

> Jay Rivett Wrote:

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

> Add some heat into the mix after you drain the pb fluid.

Thanks for the tip. So sorry about the newbie question, but how would I got about this? Just keep a torch to it for a long time?

I was also thinking about taking a hacksaw and trying to saw the cylinder in half. I assume it's junk anyway at this point.

Re: Sachs 504/1A Engine - Piston Seized

normally id just take a blunt object that fits in the cylinder and use a large sledge hammer to tap out the piston using the weight of the hammer to shock it little by little, but the sachs cylinder is different. maybe you can try this but stick something in the spark plug hole and tap it out. gl

Re: Sachs 504/1A Engine - Piston Seized

I've hacksawed the top off a Sachs cylinder. Was a waste of time as the crank was dinked anyway....new cranks aren't very expensive and you could prolly get a good used one for like $20 in the buy/sell forum.

Re: Sachs 504/1A Engine - Piston Seized

I fixed a guys moped that had a jug once. Can’t remember what it was but the piston was stuck.

After soaking, like you are doing, I looked in and saw the piston was below TDC but not too far. So, I stuck a wood dowel rod in the spark plug hole and beat it with a hammer until the piston broke free.

I also used electrolysis to remove rust from the tank. 1st time trying that. Made a nasty mess but was fun.

He had his moped back in a week and used it for moving his ass around the drag strip on race days. Guess all that banging didn’t mess it up too bad.

I would never do that for myself or to sell something but it’s what he asked me to do. Just get it to run. Proved a point about how resilient a stock moped can be.

Sorry for the long story. I maaaaay be drunk.

Re: Sachs 504/1A Engine - Piston Seized

Thanks for the tips everyone. Didn't think about trying a dowel down the spark plug hole, since it's kind of a weird angle. But sounds like it's worth a shot.

Re: Sachs 504/1A Engine - Piston Seized

I wonder how much air or water pressure applied through the spark plug hole might move that piston? (Water is safer if you can figure out a way to apply high pressure.)

Mark Kinsler

Re: Sachs 504/1A Engine - Piston Seized

> Mark Kinsler Wrote:

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

> I wonder how much air or water pressure applied through the spark plug

> hole might move that piston? (Water is safer if you can figure out a

> way to apply high pressure.)

>

> Mark Kinsler

There is the grease gun method on the wiki which is similar to your suggestion. But I don't have one.

Re: Sachs 504/1A Engine - Piston Seized

ok the grease gun comment got me thinking....you could buy a loaf of bread and shove a ton down in there till its full and just keep pounding with a dowel and filling till the crank starts moving....idk worth a shot last resort maybe

Re: Sachs 504/1A Engine - Piston Seized

> k blum Wrote:

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

> ok the grease gun comment got me thinking....you could buy a loaf of

> bread and shove a ton down in there till its full and just keep pounding

> with a dowel and filling till the crank starts moving....idk worth a

> shot last resort maybe

Bread is sort of compressible, however. Peanut butter would be more suitable in that regard, and I've heard of bananas being used as a hydraulic medium as well. In this case I'd suggest a leak-down adapter made with spark plug threads on one end and an air valve on the other (you could likely make one) would serve. For grease, you'd weld a bit of pipe onto an empty spark plug shell (the metal part) and to the pipe you'd add a 'zerk' pressure fitting that'll fit the grease gun.

But probably just steady pressure on the piston itself would do the job. One place you might find suggestions is on an aircraft maintenance site, for airplane engines are often made with 'jugs,' or removable cylinders with integrated heads.

I didn't know there were any mopeds so constructed.

Mark Kinsler

Re: Sachs 504/1A Engine - Piston Seized

I thought I replied

things I've had success with:

1) put a lot of penetrating oil I. spray in the plug hole, through the intake, through the exhaust, and under the piston (pull it out as far as you can to spray from the bottom too

2) twist it. with the jug pulled off the studs, sometimes twisting gets more torque than yanking it directly off. don't go so hard you bend the crank, but that's not likely unless you're hulking it like a maniac

3) if all above fails, put the jug back on and use an impact driver on the flywheel nut (tightening). that impact should transfer to the piston and loosen it up a bit, allowing 1 & 2 aboev more chance of success. repeat in series it'll work more fluid in and work the piston loose.

Re: Sachs 504/1A Engine - Piston Seized

u can unbolt the thing and see the damage if the crank is stuck or if its the piston stuck to the cylinder, also gives more access to spray pry and dig

Re: Sachs 504/1A Engine - Piston Seized

The grease method works but only if the piston is above the ports.

Re: Sachs 504/1A Engine - Piston Seized

> pat splat Wrote:

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

> u can unbolt the thing and see the damage if the crank is stuck or if

> its the piston stuck to the cylinder, also gives more access to spray

> pry and dig

I did this - the crank and flywheel move freely ( til the cylinder stops the movement). I'm going to saw off the top so I can hammer it out with a dowel and actually see what I'mworking with, nothing else that I have access to has worked so far.

Re: Sachs 504/1A Engine - Piston Seized

I bet you can twist and smack it loose with a socket on the flywheel, just go both directions, give it some good hammers

but yea cutting it off it a decent option too since you prolly oughhta just replace the crank anyway

Re: Sachs 504/1A Engine - Piston Seized

I would probably try the following:

>borrow another bike, or some other engine, or temporarily borrow the spark lighter from a gas grill. The idea is to be able to spark the stuck engine's spark plug.

>remove stuck engine's spark plug and clean it if necessary.

>spray in some starting fluid of the ether variety and let some of it evaporate out (some air has to be present in the combustion chamber for the stuff to burn)

>replace spark plug

>connect the spark plug wire from one of the other engines or the spark lighter to your stuck engine's spark plug

>fire the stuck engine's spark plug.

Repeat if necessary. It's not likely to cause damage, but observe reasonable safety precautions.

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