IDENTIFIED - Starts, runs a bit, dies (257cc Vog) By trailheadmike (Read 5,665 times)

[trailheadmike]

Hello all. I'm a regular on Scootdawg and it was suggested that I try here as well with my problem from member alleyoop.

I have a Vog 260 (Linhai 257cc clone) that has been great until about the 1500 mile mark. I rode all winter without a problem. Unfortunately, here's where I am right now:

The scooter starts right up but will only idle for about a minute or two and then it just dies. It will start right up again, but then the same thing happens after less time. By the third time it won't start at all.

It broke down shortly before this, and I realized at that time I had a loose sparkplug. I pulled the plug and saw I had almost no spark, and then I had no spark, so I bought a new coil.

It fired right up after I installed the coil, but then it would not stay running as described above.

Here's what I've done to troubleshoot/fix the idle dilemma:

I just adjusted the valves.
I just triple checked my hoses (all hoses and fittings were changed for US products at the 300 mile mark).
I've tuned in the idle speed and the a/f mixture.

Things I know are ok:
Gas is fresh.
Oil is fresh.
Gear Oil is fresh.
Fuel filter changed at the 300 mile mark and still looks clean.
Battery is charged.

One of the Scootdawgs thinks it might be a cracked manifold. Looks ok visually, but I guess I'll pull it off and give it a close look.

Any help would be greatly appreciated.

[Alleyoop]

YO,
250,260 guys any help for this poor soul, I sent him over here from SD due to many 250 guys here and nobody has responded to him. I would have jumped on it but I am not an electrical guru.
Alleyoop

[Cruiser]

Welcome to Scooter Doc, trailheadmike. I figured one of our Linhai specialists would have given a diagnosis by now. It is an interesting problem though. I don't feel that it's an electrical problem. I'm thinking more of a fuel delivery problem. I'm assuming that the stall happens regardless of what speed the engine is running at? If that is the case, then I would think it's a fuel delivery problem to the carb because all circuits of the carb are starved. This would point to the vacuum fuel pump being weak or not having a good vacuum source. The vacuum hoses have to be as short and as thick as possible to ensure the transmission of the pulses necessary to operate the pump. You might also want to try running without the fuel cap on to eliminate any vent problems.

[trailheadmike]

Thanks for all the input. With respect to the engine speed this happens at, I guess it probably stalls shortly after the enricher opens.

I will try the gravity feed test. I've also been reading other, old posts on scoot dawg and some with similar problems have pointed to a faulty pickup coil. When I checked my spark before buying the new ignition coil it was tiny and yellow, and then would disappear all together. That's why I thought I needed the new ignition coil. I haven't re-tested the spark after putting in the new coil, but perhaps that spark is still weak changing to none and it was never the ignition coil in the first place. I'll keep you posted.

[speedracer]

Mike, I have had two of your problems. Will start right up, stall, restart and stall, but never not start after that. I changed vacuum pumps and there was no change at all. I also changed my coil and cdi. If the manifold has no cracks in it and all the vacuum lines are good the next thing is to clean the carb. You also may want to check the enricher to see if it is working. Alley has a good link with a video on how it operates. It is possible if all those check out fine you might need a new enricher or carb. My .02

[trailheadmike]

Curiously, if it is that the carb needs cleaning, why would it start again and again, even if it does stop again?

Oh, its not the manifold.

[mthomas]

I agree so far. If you put in a new CDI, that should eliminate that opportunity of failure. Next time it does not start, pull the plug wire off, stick in a spare plug and ground it against the head and turn it over and see if it sparks. If you have spark, that will eliminate the electric issue.

Then I would pull the hose off the back of the carb and start the bike, when it starts to die, spray some gas in the back of the carb and see if it continues to run. If it does, the jet is plugged and not pulling fuel up through the jet to keep the bike running.

Also check you idle screw, some bikes will not idle after the enricher shuts off unless the idle screw is set right. Can you keep the bike running by turning the throttle?

It sound like the jet is plugged. When the enricher shuts off, there is less vacuum to pull the fuel up through the jet that is partially plugged and it dies. Eliminate the spark issue first then start with the carb.

[kz1000st]

He rode all winter. I would pull the plug off at the CDI, clean the spade fittings with an exacto blade and put it back on and see what happens. Corrosion on the plug is a mean creature. I had a similar problem with a 50cc scooter. Sometimes it would die, I'd smack the side where the CDI was and it would fire right off and run. Until I hit a bump. I just replaced the CDI and now it runs fine.

[trailheadmike]

all good insight guys. I need some time to experiment this weekend. I really think this is going to be electrical though. When I found I had the loose plug earlier as I described above, and I pulled off the cap/boot, the cap "innards" came off with it. I ended up buying a new NGK cap, and although I was able to ride a day or two after that, that's when I noticed that the spark was very weak and then non-existent. That's why I changed the coil. The plug gap is ok and the color is good. With the new coil it runs for a minute or two like I said, but I'll bet that when i get to the third try when it won't start at all I'm not going to have any spark. the scootdawg boys said that a loose plug (or a bad cap - looks like I had both) does crazy things to voltage and I might have fried the CDI. I don't know.

[trailheadmike]

FOUND MY GREMLIN - I went to check the CDI connections as suggested earlier. I see that all the wires going into the plug have little rubber "gaskets" aroung them. One wire, the brown and yellow one, had its gasket hanging out and some of the metal connector spade visible where the other wires were neat and hidden. I pulled that wire out, re-fit the gasket and plugged the wire back in, and the scooter is humming as we speak. I jiggled that wire and it stalled almost immediately. I guess that is it, and I'll see what I can do to make a better connection. Thanks guys - I couldn't have done it without you!!!

[Alleyoop]

GOOD FIND, yea those connectors on the COIL wires as well as on the CDI are not the best CRIPPED work we have seen. If you can put some solder on them or get new Connectors and and redo the wireing in the plug.
Alleyoop

[Cruiser]

Nice find. It's amazing that an intermittent connection can produce such consistent failures.

[trailheadmike]

Just as a postcript - i don't know if it was the wire or the valve adjustment made along the way, but the scooter starts amazingly quickly now. It used to have a few turns and then it would catch. now it begins to catch as soon as the starter starts going such that i almost don't know when to release the starter. just in time for summer!! Thanks again all for your attention and input.