Stuck on getting an old scooter running.

[noskinsmoke]

Hi, I am working on getting an old scooter running that’s been standing untouched for about 10 years. It’s a German model called Sachs 49er, is a 4-stroke 50cc from 2007.

I put in a new battery and the engine is turning over, replaced the spark plug and am getting a spark, made sure gas is flowing to the carb, and also cleaned the carburetor. Basically followed this guide: www.scooterfocus.com/scooter_troubleshooting.html

I don’t have a way to test the electric choke so I also tried starting the scooter while closing the air intake, but didn’t work. Kickstarting also doesn’t work.

At this point I’m stuck on where to continue. I am ruling out the Zylinder and compression issue as the scooter was running fine until it was stopped being used.

Is there anything else I can try?

[geoffh]

10 years is a long time standing,clean the carb ,jets, passage ways are all clear maybe try some starting fluid.

Geoff

[noskinsmoke]

Thank you, I cleaned the carb again, all jets and pathways are free. Tried using starter fluid and is still not starting.

Any other ideas?

[aeroxbud]

If you are getting a spark, and it's not starting with starter fluid. Check the valves.

[noskinsmoke]

Sorry, do you mean the valves inside the cylinder? Then I will check that.

Also, i just made a very confusing discovery which I cannot find an explanation for.
I found an additional connection at the manifold that leads to some sort of relay. Online I could not find any diagram or video that shows this connection and I dont know what it is for.


Even more confusing, this relay also has an electrical connection to some other relay/electrcial component and had a connection to a fuel filter that was just hanging in the air. When I was checking the fuel lines yesterday I was wondering why there was no fuel filter between the fuel valve and the carb, but just assumed it didn't have one. Weirdly the fuel line from the filter is much thicker than the actual fuel line.




Does anyone have an idea to what is going on here?

[geoffh]

Yep pretty strange it looks like some kind of attempt to boost the mixture after the carb,I would try blanking that large brass outlet and see if it helps,aerox was taking about internal engine valves tappet clearance.

Geoff

[noskinsmoke]

Finally got it to run! Thanks for the help. Luckily didn’t need to check the valves as it started after trying a few more times with a freshly recharged battery. After running for some time it now runs smoothly again.
Also ordered a newCDI and fuel filter to add and changed the engine oil.

Still confused about the extra manifold line (currently still have it connected to the relay thing). And that weird location of a fuel filter that is to big has me baffled and I just took it off.

[FrankenMech]

It could be anything but my guess would be an attempt to bypass a vacuum petcock, maybe use a valve to shut the fuel off/on with the key or enrich the fuel mix instead of the electric choke. Take it all back to stock as shown in service manuals and troubleshoot from there. Getting it to run was a big stroke of luck.

[GrumpyUnk]

I think it may be an emissions control device. Possibly an electrically operated valve that opens when you are coasting down to a stop sign or signal. It would then add air filtered through the 'fuel filter' to the intake to lean out the mixture. It would reduce vacuum in the intake manifold and avoid pulling more fuel from the float bowl via the idle mixture adjustment port. Once motion stopped it would then close?
I doubt the engine would start with that much of a vacuum leak should the large hose be left disconnected from the intake elbow.
tom
bonus points for extra guesses

[noskinsmoke]

Unfortunately I cannot find anything besides a regular service manual that only shows the very basics. I will try and see how different setups will affect the driving and maybe that will explain it.

[FrankenMech]

I doubt the factory would have used a nylon zip tie to hold a component to the frame. That is not a relay, it is a solenoid operated valve.

[GrumpyUnk]

I cannot count the number of zip ties I have seen under the seat holding 'stuff' to the frame. Mostly small items involved with emission controls. I am no longer surprised by what is used where...
It seems there are multiple versions of 'emissions control' systems, and figuring out what they do and when it something I don't plan on learning. I will learn enough to get by, but not much more. Most are harmless when it comes to performance as far as I can tell. Many riders take the emissions equipment off as soon as they can, but I am not sure it makes a difference. Most tend to add more air to the exhaust flow to allow further combustion of any HCs left unburned. Older ones looked to have 'pulse operated' flapper pumps attached to a bung welded onto the exhaust. I guess a good place to install an O2 sensor or 'wide band' sensor to tune fuel systems. I think the white filter shown is a factory part as the hoses used seem to be molded to shape so they fit under the seat without collapse or crush. I have been wrong before, and plan on it happening again, though not intentionally...
tom

[FrankenMech]

LOL, I use molded hoses a lot. I just ask to search the hoses along the back wall of the parts store. I have seen zip ties on parts, just not usually on heavy parts like solenoid valves. Emission systems vary a lot by country or region of sale. Emission systems usually suck consisting of lots of unobtainable parts, and no decent documentation or test specs. Not all emission systems are harmless.