Kymco Super 8 2T wont Rev

[edwardtennant]

Hey guys im having an issue with my mates Kymco Super 8. to start off, it has done 16k miles and has a leovince exhaust.

What the issue is is that one day he was riding it and it was all good at the usual 50mph, he stopped it overnight and it wouldn't start properly. It wouldn't start unless WOT and even then it wouldn't rev. When WOT it sounded like it was only doing ~2000RPM, sounded bogged down.
What I did was clean the air filter, carb, new plug (BPR8hs(A)), reconnected Vac line or maybe 2t line? link , and Checked the fuel filter.



However after doing this it would start better, and rev fine. All seemed good. When we were going to college today, he drove about 10 miles,ran good at 50mph, stopped for fuel, and it wouldn't start unless WOT, and once again wouldn't rev. It sounds like its starving of fuel, so what i did was pull the line going to petcock, and pull the line going to the carb, and sucked on it and fuel came out, and quite a lot of it too. So after reconnecting the vac line to manifold, I did the same while cranking the engine, but it only dribbled out slowly. We checked for VapourLock by removing the fuel cap and trying again, but it didnt work. It was also only 11C so i doubt it was vapur locked.

Thanks for reading the post, any help is appreciated. 

[edwardtennant]

After doing some research i believe that that hose which wasnt connected was the 2 stroke feed to the carb, and defo not a vac line. Is this correct? It seemed to go from another throttle assemply on the engine case, and there was oil all over the bike near the carb

[pinkscoot]

Looking at the Kymco ZX shop manual it looks like the oil goes from the pump by a hose into the intake. If these have the same engine that would be where the oil line should go. Is your friend premixing or using the injector?

I highlighted it in red. If this isn't connected and no premix that would be your problem.

[catchacuda]

Pinkscoot beat me to it ^

Indeed sounds like the oil feed line. That "second throttle assembly" is the oil pump. The engine was running without lube- that's scary! I'd worry about how the bearings and cylinder fared with no oil. If the line is hooked back up secure it with at least a small tight zip tie.

My curiosity would have me taking the cylinder off and inspecting things- that's just me though.

[edwardtennant]

The hose going into the manifold is the vaccum. If sucked it makes fuel come out of the petcock, and the one on the side in the link is connected to the oil pump and the carb. It is also using the injector, not premix

[pinkscoot]

The super 8 must be different from the ZX50.

[edwardtennant]

After we oulled the head it becamd clear that i needed new piston and cylinder, its a mess in there, suprised it starts at all