So I've got a Vento Triton Li (2-stroke) that for the first ~300miles ran perfectly. Lately, however, it's been giving me problems. Suddenly it would misfire/stumble at higher RPM then die when the RPM wound down. However, it starts right back up after. It's not having problems getting fuel, good spark, the only thing I can think of is that the oil pump died. If I pull the oil line off the carb and turn over the engine (no plug), oil should start coming out the line eventually, right?

Any help anyone can give would be appreciated.

On revisiting, it is definitely not the oil pump. If I pull the line off the carb and rev the engine (using pre-mixed gas) some oil starts coming out of the line, so the pump seems to be fine. I'm wondering if I have a bad CDI or something, but I have no idea how to check. Blah, guess I'll have to find a shop to take it to.

Somehow, using 87 octane instead of 93 octane fixed it. I guess the 93 was just too difficult to ignite? I don't really know, but at least it works now!

For what it's worth, I had a problem with my 2007 Triton Li where it would mis-fire and stumble at full throttle using 87 octane although it would stay running when I backed off on the throttle. I found the problem was the spark plug. I replace that and the problem disappeared.

Yeah, I was wrong, my scooter is still having issues with the 87. It only seems to run well after it has been warmed up for a solid 20mins. I'm going to go pick up a non-iridium plug and see if that makes it any better.

Put in a standard plug...no better. I want to throw this thing off a cliff. It's driving me crazy!