Wonjan Woes !!

Hey Guys.

I need help please. My Wonjan 200GYB has developed a illness I am trying to diagnose. When I get up to about 7000rpm, the motor starts to splatter and misfire. A While ago I first noticed it but it was not nearly as seveare and very intermediate. I suspect a glitch with the Ignition module. I say this because when the splatering starts, the revcounter starts to wonder madly around 5000 - 6500rpm, even though I am at 7000 - 7200rpm. I worsens as I try to go higer and disapears when I get back below 6800rpm. I am quite sure that it is not fuel starvation as you can feel there are throttle power left and giving some choke makes no differance.

Advise please Lads ??

Kind regards

It does sound as if it's the ignition system. Before doing anything else inspect the spark plug to see what make it is. If it's a unknown Chinese make like "TORCH" or some other junk, replace it with an NGK. Japanese derived engines run best on NGK or ND (Nippon Denso) plugs.
This is a common problem with Chinese bikes as others will testify. The owners manual might even give you the Japanese equivalent in the characteristics listing, or we could ask another SA based member, like Skip_200GY for instance, he's changed his plug straight out the crate!.

Possabillaty !!! I just ask myself why the rev counter then goes grazy? The only common part is the Ign. Module. I will swap the plug this weekend and see. I am also trying to borrow a module from a friend to try and swap it out in order to verify my suspuission.

I will advise on what I find !

Lekker weekend to you !

If that's not it, check your carb boot (insulator) between the carb and engine. These things are made of cheap rubber from factory and sometimes develop weird cracks that leak air when under load at higher rpms.

Just an idea...

CC

Thanks Carl, will do. But this usualy goes with ideling problemes due to over lean mix and does not explain the "Funky" rev counter. I will check it out any way.
W.

Spend most of the day stripping the bike. Removed the cover over the magneto, Checked the magnetic sensor for the ign. Spark plug lookes ok with healthy color, will change it though for a NGK. All wires seems fine as well.

I am stumped, Any other Idea's? Could the coil be at fault? Only thing left is the ign module, I Think.

My money is still on the plug. Its colour only means the mixture is OK, but misfiring doesn't show up in its appearance.

The rev-counter bit is a mistery, although being driven by the CDI unit, the misfiring could be generating electrical "noise" or interference that affects its behaviour. Consider that, assuming the CDI and coil are OK, but a faulty Chinese plug refuses to fire, the voltage that was generated by the system has to go somewhere, and as it was not used by the plug it can end up being absorbed by the coil windings or other internal components of the CDI box. This can affect the rev-counter.
Electronic rev meters are not like the robust classic magnetic eddy-current type. They are sensitive 1mA FSD meters, and, although heavily damped and ruggedised for automotive duties, are very sensitive and will respond to very small electrical signals.

I see you've been delving into the magneto and its sensor, pulser or trigger coil. Apparently the gap between this and the rotor is critical and could also lead to a weak spark and therefore misfiring. Not sure what this gap should be, but I believe it has to be as close as possible to the rotor without actually touching.

The gapping on the pickup is fixed and can not be adjusted, but here is the good news. I swapped the plug with a NGK and checked each and every plug connector on the wiring loom. Probleme solved !!! I unfortunately have not pinpointed the fault butttt.......... Its gone, and I hope it stays there........GONE !!!!

It was however interesting for me to discover that the magneto chamber is oil filled. It also houses the gears for the electric start. One sould think this to be a dry chamber ?

Well, so far so good !

Thanks again for all the assistance and advice.

Cool Runnings!

That's great news. I often fall for that trick of checking-adjusting-tweaking, lots of parts (while I'm in this area...while I got this bit off...), and then once the problem goes away I have no idea what did it!.

I bet the plug had something to do with it. I've had that problem as long ago as 1982 when I had a couple of eastern european vehicles, a Jawa bike and a Skoda car, both times it was the "PAL" brand plugs. Same with all my Chinese bikes except the Qingqi/Qlink that comes with NGK as standard.

I was also surprised to find the magneto running in oil on my Qingqi. The Honda-cub derived designs run it in a dry chamber.

if your issue is persisting then you may have a vacuum issue in your gas tank. it is not allowing gas to flow into your carb properly.

take the gas cap off or loosen it completely with it just locked in place so gas does not splash out and run it down the highway. that is the problem i was having. i thought that it was my valves needing adjustment but it was not. the bike did like the valve adjustment but it gradually did start sputtering at speed on the highway again.

2 trips to the dealer has now officially fixed the problem!!! i also went down on my jetting since i went way too big (135). when the mechanic fixed the jetting it made the problem worse!!! then he determined it was a vacume problem. i went down the highway with the cap loosened but locked in place and it was much better. they replaced a vacuum line and boom. fixed.

if your problem is resolved after all, that is fantastic!!! i just wanted to mention this as we had the same symptoms but i knew it was not my plug as it has been replace a few times already.

This I have heard about quite a couple of times. Specialy on those caps that has the litle breather pipe that goes into the neck just below the bars. The pipe kinksor gets blocked by someting and the shite starts. Bike stands for a couple of seconds, probleme gone for a couple of minutes. And has this Puzzled some mechanics !!??!!

Quote:

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Originally Posted by volksjagger

they replaced a vacuum line and boom. fixed.

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My Euro spec Qingqi doesn't have anything like a vacuum line anywhere. There's a vacuum take-off stub in the carb manifold adaptor but it's blanked off.
However the parts book shows some sort of anti-smog device that must be fitted to US spec bikes. Was the pipe replaced item 7 in the attached drawing?:

http://www.lao-japan.com/data_catalo...s/image024.jpg

Quote:

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Originally Posted by Wolfie

This I have heard about quite a couple of times. Specialy on those caps that has the litle breather pipe that goes into the neck just below the bars.

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I've seen those kind of breather pipes on lots of dirt bikes. Never understood why they're used only on them and not on street bikes.
Our bikes have just a tiny air duct built into the cap that lets air into the tank.

Quote:

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Originally Posted by forchetto

I've seen those kind of breather pipes on lots of dirt bikes. Never understood why they're used only on them and not on street bikes.
Our bikes have just a tiny air duct built into the cap that lets air into the tank.

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hello friends unfortunately not speak English but I want to help :thumbsup:
Operation of the system
If there is negative pressure in the exhaust, the reed valve of the air induction system is open and
allows the passage of fresh air, coming from the box of air filter for the exhaust collector.
This process of burning occurs in a range of temperature from approximately 580 to 720 ° C
and significantly changes the volume of hydrocarbons (HC) and carbon monoxide (CO)
turning them into carbon dioxide (CO2) and water (H2O).
This system injects air filter, clean, in the exhaust outlet to help supplement the burning of unburnt gas inside the cylinder.
The working principle is based on the difference in pressure adjustment and the correct mix of
carburetor, which is deliberately impoverished.
This adjustment is made in the factory and should not be changed without the correct use of an analyzer of
gas, unless the regulation of idling through the screw of acceleration.