Sachs With Airflow Problems

Jake Van Order /

I have a Sachs 505/1D engine that has given me problems all weekend long with no fix in sight.

First, what does it do?

It will accelerate only if I give it 3/4 throttle. Anything more and it bogs down and dies. After I reach 20 mph or so, the moped will act somewhat normally and I can then give it full throttle. Also, if I fiddle with the choke, it works alright but nothing consistent.

How did this happen?

No idea. It happened over night, while I was not riding it. The night before, though, I did run out of gas and I did clog my jet. I filled up and clean my jet and everything was fine. After riding it, I parked over night and rode it in the morning. At first, it was just driving strangely. Slowing down suddenly, loss of power uphills and while changing gears, and general slowness.

What have I done.

I have replaced my carburetor with a different bing model. I have changed my stator plate. I have set my timing to many different settings. I have replaced every gasket from the airbox to the cylinder. I have changed my airfilter. I have jetted and rejetted.

Any success?

Yes and No. I jetted up last night and that kinda worked. I was going slower than before this whole mess started, but I wasn't stalling if I gave it full throttle. Today, though, the moped just bogged down completely. I can reach full speed if I keep the choke halfway in but that is not consistent.

One thing to note:

I did just rebuild my engine but this isn't a clutch issue, I think. It is gas because if I choke the bike, it runs alright.

So, any ideas? I'm in a bad place right now because the moped is my only transportation and this one is not working to the point where it's safe in traffic.

Any help would be greatly appreciated.



Re: Sachs With Airflow Problems

John Joedicke /

Clean you fuel valve, you probably have sucked up all the crap in the bottom of your tank, thus restricting flow.

Re: Sachs With Airflow Problems

Jake Van Order /
jake OP

I did check this. I have very good flow and nothing is stopping any fuel. I am thinking that bad gas was put into my tank, some how. I didn't mix the batch of gas so it's questionable.


Jake Van Order /
jake OP

I did replace the choke assembly, air filter and airbox to no avail.

I also checked my timing, cylinder head, rings, exhaust port, exhaust, clutch plates, petcock and reverted back to my old carburetor. No good.

It will still bog down whenever I give it gas and only if I choke it just right will it run the way it should.

MBartell, any ideas? Anyone?


Re: Update

Jason Luther /

is it at all possible that you have an air leak somewhere?-jason

Re: Update

Jake Van Order /
jake OP

That's definately what I'm thinking. I did replace every part from the airbox to the carburetor manifold so there wasn't a leak.

Last night, in desperation, I just put a larger jet and it worked. Although that is great and I am happy that my bike is back to normal, I am deeply mystified why a jet size would need to change over night. I did just install a performance exhaust a couple of weeks ago and maybe something in it broke in and needed more gas. I'm just not sure.

We'll see if this sticks.


Re: Sachs With Airflow Problems

Jake Van Order /
jake OP

So, it was the jet.

For some reason, the jet needed to be replaced with a bigger size. Overnight, my moped decided to need more gas.

Strangely enough the moped is running better than it ever has.

Thanks jason and double for the ideas, though.


Re: Sachs With Airflow Problems

This happened to me with my kitted Sachs.

I went from a 52 to 62 in one night. It was crazy and made no sense whatsoever, but similarly, my bike then ran better than ever before. Glad your Carrier is running good.

My Sachs however, is back to bone stock 50cc's.

The progression over 13,000 miles:

Stock 50

50 + biturbo

70cc + biturbo + 52 jet

(4 months later) 70cc + biturbo + 62 jet

(back to) 50cc + biturbo + 52 jet

(now) Stock 50

...but not for long...

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