Lifan KPX Throttle Response / possible detonation
 

Well after riding my KPX some more, I wanted to report this. I haven't mentioned it before now as I was hoping the control module would "learn" so to speak. Simply put a CARB has better throttle response than this bike has. It has been that way since the day I started it. There is a noticeable lag in the twist of the throttle and the engine reacting to throttle input.

Another issue I suspect is going on is I heard what sounds like detonation at low speeds. And no, I was not lugging a gear too high for the speed I was traveling. Not sure if it truly is detonation (spark knock) or something is vibrating under the tank towards the top end of the motor. I'll know more when I have time to yank the plug to read it. Hopefully it isn't a lean condition as I have no idea how to richen the mix :hmm:.

Just an update to this here community, I'm not one of those people who champion anything they own as being the greatest thing since sliced bread. I will spit the good, the bad, and the ugly. :lmao:

I have no issues with mine. You can richen up the idle mixture. There is what called the Idle gulp adjustment screw on the throttle body. Some of the Xpect guys had this same issue you describe and that fixed it. Here's a link to the instructions.
https://netcult.ch/elmue/HUD%20ECU%2...4%20Manual.pdf

Awesome! Thanks Jerry I will give that a try.

Would 93 octane help your KPX?

On pages 29 and 30. Thanks Jerry!
Note that in the instructions on page 30 they call the screw a bolt.
PS, no issue with my KPX's idle either.

Let us know if it helped.

The KPX doesn't need 93 octane. It will run fine on 87 octane which is what the specifications call for. It probably wasn't tuned correctly at the factory and is running a little lean. At least we know how to correct it if it happens. When I did my valve adjustment i pulled my plug. Nice light tan color.

It starts on page 40.

I sure will, I'll tinker with it this weekend.

RE idle gulp adjusting screw:
Not finding it my kpx.

Mine is kinda jerky at low throttle too. I checked the plug and it is not a nice tan, it's white and too clean. Idles good. I haven't sprayed wd40 on the intake yet, but the bolts are tight and clamp to the throttle body is tight. No CEL.

Any ideas?

I never physically looked for it on my KPX yet. I'm wondering if this is something that has changed on the KPX or may have a cover over it. Now i need to take a closer look to se if it even exist anymore. :hmm: Did you happen to take pictures of the throttle body?

I didn't until just now. The photos pretty much show what you can see from the right side. I did pull the bracket off that holds the throttle cable, and removed the wheel the cable attaches to. The left side has some sensors that I did not remove, but they don't look like there's room to have an adjustment screw under them.

I was riding it yesterday without a helmet and ear plugs (I'm in Mexico riding around a small town) and could hear the tinkle of spark ping. It's not a knock, and it's for sure not detonation (very destructive). The kpx is the first vehicle I've had with efi on an air cooled engine, so it could be normal. Still don't like the plug color.

My V6 ford van has spark ping when you start to load the engine (starting up a hill). Efi in cars with knock sensors advance the ignition until there is a knock, keeping the ignition as advanced as it can be. Seems to work with liquid cooled engines for a few hundred thousand miles...

Right side
https://journaldelpacifico.com/tbody_right_side.jpg

Left side

https://journaldelpacifico.com/tbody_left_side.jpg

I have not dove into this issue with my KPX yet. I'm ashamed to admit the bike sits alot of the time, still doesn't have many miles on it at all. But I did start it up yesterday and let it run for a bit. The issue is still there, I need to figure it out. I plan to use the manual posted to see if this "gulp screw" exists on this model. I'll also see if I can make a video of what it's doing. I also need to pull the spark plug and check the color.

PATHN, Did you ever resolve the issue with your KPX?

detonation ?pinging
 

In response to this thread I have a 2023 KPX 250 with 25 miles on the clock and looking at this EFI manual shown on this thread my injection does not resemble this configuration. I am aware of the re-mapping of the cdi which I will take on at a different time to fix hesitation in throttle. I do not see any Idle gulp adjustment screw and have looked everywhere. The issue is: even though it idles ok it sounds almost like pinging/ engine ping/knock on immediate acceleration all gears. If it is too lean I cannot see where there is any adjustment screw. I am using 90 Rev octane from the get go. I thought it was a rattle and have tightened , zip tied everything under the sun.
I have checked all clamps and checked for air leaks.
email. is ok: rmilesmeritage@gmail.com

Ping/Click KPX 250 2023
 

I picked up my KPX 250 a couple of weeks ago and I'm having the same issues as others with the ping/click during acceleration. I don't hear it at speed or idle just when I'm going through the gears. It can be loud so with a helmet on I have no issue hearing it. I checked the provided manual and this bike has no gulp screw. No adjustment screws at all that I can see on the 2023 KPX 250. Anyone find a solution to this issue? I only have like 50 miles on the bike. I contacted Venom the folks I got the bike from with zero response.