Rough running

[Jdbooth1995]

Hi guys! so I've had my kymco about 2 years now I've had some ups and downs with it but never this major and i need help! i changed the bike's air filter for a K&N style filter and after changing it sounded really powerful but the pick has increased imensly however when the speed get to about 10-12mph the power just dies out now i thought it was the filter as before it had that on it didnt have a filter in the box removed that and it was just as bad so then i checked the auto choke and that wasnt the problem so then i changed the fuel filter for a new one as the one before was the original that still did'nt fix the problem the only thing i havent checked is the carb but i found out when i rode it down for my friends workshop to my place that if i keep throwing the throttle back and forht it wil pick up more speed but i dont think that shoul dbe doing that, xan anyone help with this problem as am really grasping at straws here!

[baddi]

Hi guys! so I've had my kymco about 2 years now I've had some ups and downs with it but never this major and i need help! i changed the bike's air filter for a K&N style filter and after changing it sounded really powerful but the pick has increased imensly however when the speed get to about 10-12mph the power just dies out now i thought it was the filter as before it had that on it didnt have a filter in the box removed that and it was just as bad so then i checked the auto choke and that wasnt the problem so then i changed the fuel filter for a new one as the one before was the original that still did'nt fix the problem the only thing i havent checked is the carb but i found out when i rode it down for my friends workshop to my place that if i keep throwing the throttle back and forht it wil pick up more speed but i dont think that shoul dbe doing that, xan anyone help with this problem as am really grasping at straws here!

Removing the filter from the air box is even stupider than using a K&N style filter. Both solutions will let vast amounts of dirt and unwanted stuff to go directly into your engine and can result in serious damages.
It will also let more air into your engine, so unless you have changed the setting and jets of the carburator, you will run lean, which can cause the engine to overheat and damage it seriously. Dirt in the carburator can result in the same.

There are 3 possible solutions to your problem, if it is connected to the filter:
- You have gotten dirt in the carburator, try cleaning it.
- You get too much air, recalibrate the carburator to the increased air flow.
- You have burned the piston rings, or valves and there are no compression in the cylinder now. Replace pistonrings if damaged (remember to check gab), replace cylinder if damaged, grind the valves and valveseats or replace the cylinder head.


Lesson to the next time, NEVER compromise on the filtering ability. Even free flow foam filters need to be wetted in filteroil to filter just a little bit. Also, NEVER start puzzling with the air, if you don't know what you're doing.

[streido]

99.9999999999999% you need a bigger main jet. A K&N will req a larger jet than a stock airbox set up even if that stock box had no actual filter in it.
 
Depending which filter you bought you will need to up the main jet from 82 to anywhere between 88-100. I run 90-92 depending on the weather/time of year with my open filter.

Like Baddi said your getting far too much air in now for your jet and the fuel going in doesnt match it so you'll be running way lean. Try taping over half to 3/4 of the K&N filter to restrict the air in, if that works then its def the main jet is too small.

[streido]

Btw, unless your willing to spend time tuning in the correct jet size and know how to properly do plug-chops then o would go back to the stock box or chances are you WILL damage your engine.