You will need to contact American Lifan. They will either send you a programmer to reflash the ECU or have you send in the ECU for them to reflash.

I just contacted them and they told me to send my ECU to Venom Motorsports.

Tick/Click KPX 250
 

Well bummer on sending in the ECU. I just purchased this biking knowing about ECU issues with the bike. When speaking with the sales guy at Venom I asked if they would put the latest ECU into the bike and was assured it would be included. I need to call them, this isn't adding up. The throttle will give some slight hesitation and I know that points to the ECU or adjust the throttle. I've checked the throttle and it's fine, no major slack or kink. Well, heck.

Venom bought up a bunch of stock due to EPA regulations causing many of Lifans bikes to not be legal for the immediate future until they can pass certain regulations. You likely got shipped a bike from that pool of vehicles with an older ECU and Venom was simply not aware of it because they knew all of the bikes they were shipped had the upgraded ECU, and yours simply didn't.

KPX 250 Knocking Clicking
 

Well after many, many attempts to have someone anyone over at Venom contact me it's a bust. My KPX 250 is a lemon and the company just isn't getting back to me on this issue. I called all last week, called this week and they keep telling me "someone" will contact you and they don't. At high idle the bike sounds like there is sand in the motor and when I drive it the bike knock/pings as you get down the road. I'm afraid it will leave me on the side of the road so I don't go far from home. I haven't even got the bike past 45 mph. I wouldn't in fear of my life. I have changed the old and put all the proper oil in the engine. I did find some flakes but the oil wasn't that bad. I think this thing is going to seize up while riding. I did ask them about the ECU and the customer care woman on the phone told me the bike was too new and it has the latest ECU flash. I guess I'm going to sell this junk online as scrap. I'm out over $3,000 buck.

If was my bike I would empty the fuel out and get fresh from somewhere else and see if that helps. I know it can’t be bad fuel, but it seems like it. My thoughts…

KPX 250 Knock/Ping/Rattle
 

I've tried new fuel with no change. That was one of my first thinking. I will keep posting here "if" Venom ever comes back with any response or help diagnosing this issue, so far nothing.

Did you check to see if you have an exhaust leak where the header meets the head? You will get a similar noise with an exhaust leak.

If you are not having luck getting in contact with Venom then call back American Lifan and inform them of your issue and see if they can offer an alternative. Sometimes you have to play the game a bit to get what you need. Just try to keep your cool, don't let your emotions run away with you and just approach it like a math problem that needs to be solved.

As for metal flecks in the oil, if the engine has less than a thousand miles on it, that will be normal. Seeing as yours has just 50 ish miles on it, expect a lot more. Part of the normal break-in process. Without being able to hear the engine for myself I can't give much diagnosis, but even if the thing is going to fail, Lifan has a 2 year warranty on those bikes if I remember correctly. Use it. Don't sell it just because you are emotional.

good luck

You don't have a lemon and it's not scrap. You should upload a video of the noise so we can atleast hear it. The engine will quiet down as you break it in. Everything you've said is normal within spec.. I have 600 miles on my kpx and iv been running 90 ethonal free gas. Every once in awhile I also get a slight ping. Ecu has been sent in already.... it's normal. These are small thumper engines. They're going to sound like a well oiled sowing machine.

MotoJane, Another possibility is that the Valves may need adjusting. Even though it is a new bike, As many of us know on the forum. Most of these bikes come from the factory with valve gaps set to tight or even too loose.

Valve Adjustment KPX Ping/Click/Knock
 

I worked with my neighbor on doing a valve adjustment. He's a retired ASC mechanic. Wow, things went from bad to worse if that's possible. Something is wrong with this engine. The valves were tight but after doing the valve adjustment this thing click and clanks down the road. I wouldn't trust driving the bike more than 2 miles from my home. I'm at a loss. These bikes really don't have much in the way of adjustments. These noises in the engine are not normal, I've been riding bikes for over 30 years.

Do you have any video so we can hear? That would really help in diagnosing the problem.

With respect here, after adjusting the valves and it went from bad to worse, that’s pointing to the valves. We’re assuming that the engine was on the compression stroke when the valves were adjusted? Easy to to get things wrong here. Plenty of info. on how to adjust them here. Thinking out loud…