Was this sachs cylinder seized??? Pics

Matt Wilson /

The 1980 sachs that I bought a few weeks ago ran about 25-27mph as I got it. After a few minutes the bike had a loss of power and would only go 5mph up a slight incline. It would still reach 30mph downhill. I thought that old rings might have been to blame odometer shows 4000 mi

When I removed the cylinder it looked like this

<IMG src="http://www.rpi.edu/~wilsom/ii.jpg">;

I ordered new rings, but they haven't arrived yet.

I also wanted to have the cylinder honed out so I removed it. This cylinder is very narrow and I couldn't find anyone with a small enough hone. I'm going to check the bike shop where I used to work because they had some ones that I think will fit.

Now this is the wierd part. In the exhaust port there were some really big drops of metal.. kind of like someone dripped solder inside....but why would anyone solder the exhaust port?

So I thought about it a little more, and thought that maybe someone had siezed the engine so bad that the piston melted and dripped down the exhaust port. But if this did happen, it obviously wasn't with the current piston, because that one seems to be in ok shape (except for the light scoring). And also there seems to be no aluminum smearing on the cylinder.. just light scuffing on both the cylinder and piston

Another possibility is that the weld was part of the engine construction. But another sachs owner said that his port was smooth and circular. So maybe this is just a defect in my engine.

I don't know... I can't really think of any good reason that the exhaust port looks like it does. In the picture below you can kind of see what I mean. I have sanded it down a little, but in the case that it is holding my cylinder together, I don't want the weld to break.

<IMG src="http://www.rpi.edu/~wilsom/sachsport.jpg">;

Also this is a sachs 505 engine which has a one piece head and cylinder.

Re: Was this sachs cylinder seized??? Pics

looks like it could have been seized to me....

Re: Was this sachs cylinder seized??? Pics

Matt Wilson /

But seized so bad that an aluminum piston melted and dripped into the exhaust port?

I don't know...


Re: Was this sachs cylinder seized??? Pics

chuck russo va /

i think u should get a new cylinder and piston w/rings, my local ped shop has some cylinders but i dunno about pistons, i saw them last time i was there. if u want them let me know and i will give u the number because they ship all over the us

Re: Was this sachs cylinder seized??? Pics

No... there is no way the piston melted and 'dripped' and puddled into the port.... engines don't get that kind of hot.

The pics aren't that clear... but off the top of my head... It almost looks like that entire exhaust 'spigot' was welded on by somebody.. (not the factory original)... it sure looks like some ugly welds around that spigot.

It isn't JB Weld is it ?

The piston looks a little funny too... the bottom ring looks fine... but the top ring appears to 'disappear' into that gray spot... (like its an aluminum smear?.. from a seizure)

Cylinder wear... Still good ?

How do the pro's tell about the cylinders usefulness as is ?...

... (aside from big scuffs and gouges)... they measure the cylinder diameter at the base with precicion tools.

You probably don't have precision tools... but you can get a crude idea by using fine feeler guages.

Stick the piston back in the correct way... and line the edge of the piston skirt up with the base of the cylinder... then stick the biggest feeler guage in there you can.

The feeler guage will have to bend... and the wider the guage the more inaccurate the measurement... so you have to take that into account

Then read a manual you may have.. for MAX piston to cyl clearance... it will prob say... (.0025" or .003") ??

And it may say...

... cylinder diameter is 1.250" (stock)

... piston diameter is 1.249" (stock)

(which would give .001" clearance.. stock)

Then it may say... max piston to cyl clearance is .003"

so... if your cylinder is worn to 1.255" dia.. then clearance with a new stock piston will be .006".... way over the recommended .003" clearance.

You would need a bore job and oversize piston in that case.

(the above numbers were made up as an example.. do not use them for your situation)

Re: Cylinder wear... Still good ?

Matt Wilson /

If engines can't getr hot enough to melt the cylinder into liquid than there are only 2 explanations that I can think of.

1. Sloppy manufacturing

2. A previous owner welded something in there

I will get some feeler gauges and check up on the dimensions. I don't have a manual so I don't know the clearance specs. Maybe someone else does. If not I'll post whatever numbers I can have and maybe you can help.

Do I use the feelers with the rings in place or should I remove them?

I think the black stuff that looks like a sloppy weld around the outside is actually black silcone sealant. The previous owner put the stuff everywhere. But I will check, perhaps there is a weld underneath it.

And there is no aluminum smearing on the piston or the rings.. you can take my word for it.


Thanks for the offer. I'm hoping that the new rings and hone will get this ped set straight. If not I'll probably part it out.



Re: Cylinder wear... Still good ?

chuck russo va /

take your cylinder and piston to a moped shop, they checked my clearances for free just bring them in and they should do it for free if not i doubt it will cost more than 5 bucks

Re: Cylinder wear... Still good ?

Matt Wilson /

Yesterday I got the cylinder bored out. I finally ofund a hone at a motorcyle shop one town over. They didn't even cahrge me.

When I got home I began to smooth things out with the dremel inside the exhaust port. I noticed that what I thought was a sloppy weld was actually a carbon deposit. It was really hard carbon deposit...not the gooey stuff I've seen on other peds. It was so hard I actually had to use the dremel to clean it up.

The exhuast port had two little metal wedges inserted that sloped down from the cylinders exhaust port. That is the shiny part you can see in the picture. I smoothed these out but didn't grind them down.

I just can wait for the rings! I really want to get this going!


Re: Was this sachs cylinder seized??? Pics

i have seen cylinders that were not running good cuz lack of oil. they actually had holes in them. you might want to get it bored out.

Re: Was this sachs cylinder seized??? Pics

Matt Wilson /

Yeah 2 strokes kind of need oil...

It worked before, and the rings had 4000miles on them. It was time to replace them.

Do you know what you are talking about?

Re: Was this sachs cylinder seized??? Pics

yes i know what i am talking about i been working on small motors since i was 7. ive seen my bros weld it self shut beacouse a small (very small)lack of oil. that could be many things. ive seen mopeds go long after 4000 miles before they needed new rings.

Re: Was this sachs cylinder seized??? Pics

Matt Wilson /

"yes i know what i am talking about i been working on small motors since i was 7"

A year later and you still don't know what you're talking about.

Just kidding dude...but I had to jump on that one.


Re: Was this sachs cylinder seized??? Pics

lol good one im not the greatest mechanic but im learning. lol im olny 15

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