Kymco Cobra Cross 50cc- bogs down and dies when it gets hot

[tjwebdude]

Hello Kymco fans.

I have a 2004 Cobra Cross, 50cc... It's also known as a Top Boy (see below).

I've had this awesome scoot for a couple years.  Tops out at around 45mph. 

Last fall, it started to die on me after the engine got hot... usually after driving 10-15 minutes or a few miles.  It doesn't die right away, rather it's like  the fuel is slowly stopping... or maybe air/fuel mix is getting messed up.  It just bogs down... won't go above 20-25mph.  If I continue to push it like this, it will eventually die.  Then I won't be able to run it again until it completely cools down.

I drained all the gas, changed the fuel filter, put in fresh gas. Same thing... bogs down after getting hot.  When I checked the air filter, I noticed some gas was getting blown back out of the carberatour.. that doesn't seem normal either.

Any advice would be much appreciated.  Keep scooting!

[Areomyst]

Have you checked your compression?  It's unusual for a heat related issue to be coming from the fuel delivery system.  I would check the compression.  You can remove the exhaust and look up into the exhaust port with a flashlight and visually inspect the piston and cylinder.  It's quick and easy, takes about 10 minutes. 

The Cobra is one of my favorite scooters.  The engine is basically the same as the AC Super 9, People 50, Vitality 2t, etc.

Keep us posted.

~Josh

[axy]

Had Cobra 1999 from 2002 do 2004.
It is still alive and kicking and being driven by the new owner...

[zombie]

this sounds like another kymco cdi failure. read some of the similar posts. i replied in some others this is the same problem i have had since day 1 w/ my scoot. tryiny to find a more reliable unit as we speak. (so to speak) try jiangwayne.com. these guys are good, or buy the factory cdi by the six pack.

[Calvert50]

I had some similar symptoms with my ZX-50.  It acted like gas starvation or an intermittment spark plug.  I checked the fuel filter and replaced the spark plug. It still acted up.

As others have said, the CDI unit turned out to be the problem.   They don't just up and die completely.  They'll work sometimes and not other times.  Sometimes they'll cut out at higher rpms, thus mimicking a gas problem or a spark plug issue.   

However if you have the service manual and a voltmeter and you're handy with this stuff, you can measure all the CDI voltage parameters.  This was the dead giveaway with my problem.   I replaced it, and it started and ran perfectly.

I vote for a CDI problem.