KPX Throttle Position Sensor tuning by ear????

Bill Hilly · 10-14-2023, 09:08 PM

I like my new bike, but honestly I would rather it been a carbed bike. I know how to tune one. I mentioned when I first got my bike that it acts like a carbed bike that is started on choke, and will idle after the choke is open, but will sometimes die, if you touch the throttle, until it warms up. I have been noticing after joining a KPX Facebook group, and seeing YouTube videos,that this is very common, and a bike that doesn't do it is probably the exception, rather than the rule. I have seen a video of a guy turning the TPS a little, and evidently helping, but I don't know if it really helped, or his motor had just gotten warmer during the process. The bike just acts like it wants to run lean at idle, and from the look of the slot in the TPS, it looks like the thing is turned counterclockwise all , or most way. There is no visible slot showing above the screw that holds it in place, but the slot is visible below the screw. Wouldn't turning it act like an idle mixture on a carb.? Can they just be experimented with till satisfied? Should I contact Venom?
I appreciate any help I can get. Thanks

Boatguy · 10-14-2023, 09:52 PM

From doing TPS calibration on outboards….

They basically just run in a range.

As they rotate, they put out a different voltage for each position they go through.

What typically happens is the ECUlooks at the entire range and calibrated itself to the TPS. You can do this through software, you can force a calibration, but typically you don’t. You just allow the computer to figure out its own calibration. It just looks at the voltage for completely closed and the voltage at WOT and works out a mapping for everything in between.

So in other words, using a setscrew and changing its rest position isn’t going to do anything. The computer should just re-map it when you do that.

If you want to adjust the amount of fuel the engine is getting when it is completely closed, you have to change the mapping of the fuel flow at idle. I don’t know what software we have for that on that particular bike. We did have some for the xpect in this forum.

Of course this may or may not all apply to the KPX. This is just TPS knowledge from other small engines.

Hoping it helps in figuring out your situation

Bill Hilly · 10-15-2023, 03:47 PM

I just turned it clockwise a little, and it improved it a whole lot. It's been raining on and off today, but I can probably fine tune it a little more.

**JerryHawk250** · 10-16-2023, 08:11 AM

Quote:

Originally Posted by Bill Hilly

I just turned it clockwise a little, and it improved it a whole lot. It's been raining on and off today, but I can probably fine tune it a little more.

So apparently that does work.

My bike ran perfect from day one so i never messed with it. Good to know.

Boatguy · 10-16-2023, 05:45 PM

Glad that worked. I guess it’s a much more simple ECU than one of these complicated newer outboards

Bill Hilly · 10-16-2023, 06:04 PM

Quote:

Originally Posted by Boatguy

Glad that worked. I guess it’s a much more simple ECU than one of these complicated newer outboards

It's not exactly right, mainly in the fact that it's idle is not a perfectly steady drone.and today I fired it up before changing the oil, and it was taking throttle good, even before it had a chance to run long, but as I was letting it warm up some, the idle started getting rougher, and the I revved it a little, and it idled "good enough", that it would never be an issue as long as a rider wax on the bike to give the throttle a little twist occasionally, if stuck at a long light, or something. Unless we get an Indian Summer, then there's not much decent riding weather between now and mid- late February here in WVa

10-14-2023, 09:08 PM	#1
Bill Hilly Join Date: Feb 2021 Posts: 947	KPX Throttle Position Sensor tuning by ear???? I like my new bike, but honestly I would rather it been a carbed bike. I know how to tune one. I mentioned when I first got my bike that it acts like a carbed bike that is started on choke, and will idle after the choke is open, but will sometimes die, if you touch the throttle, until it warms up. I have been noticing after joining a KPX Facebook group, and seeing YouTube videos,that this is very common, and a bike that doesn't do it is probably the exception, rather than the rule. I have seen a video of a guy turning the TPS a little, and evidently helping, but I don't know if it really helped, or his motor had just gotten warmer during the process. The bike just acts like it wants to run lean at idle, and from the look of the slot in the TPS, it looks like the thing is turned counterclockwise all , or most way. There is no visible slot showing above the screw that holds it in place, but the slot is visible below the screw. Wouldn't turning it act like an idle mixture on a carb.? Can they just be experimented with till satisfied? Should I contact Venom? I appreciate any help I can get. Thanks
	0

10-14-2023, 09:52 PM	#2
Boatguy Join Date: Feb 2021 Location: Northeast Posts: 929	From doing TPS calibration on outboards…. They basically just run in a range. As they rotate, they put out a different voltage for each position they go through. What typically happens is the ECUlooks at the entire range and calibrated itself to the TPS. You can do this through software, you can force a calibration, but typically you don’t. You just allow the computer to figure out its own calibration. It just looks at the voltage for completely closed and the voltage at WOT and works out a mapping for everything in between. So in other words, using a setscrew and changing its rest position isn’t going to do anything. The computer should just re-map it when you do that. If you want to adjust the amount of fuel the engine is getting when it is completely closed, you have to change the mapping of the fuel flow at idle. I don’t know what software we have for that on that particular bike. We did have some for the xpect in this forum. Of course this may or may not all apply to the KPX. This is just TPS knowledge from other small engines. Hoping it helps in figuring out your situation __________________ 2020 Lifan x-pect
	0

10-16-2023, 05:45 PM	#5
Boatguy Join Date: Feb 2021 Location: Northeast Posts: 929	Glad that worked. I guess it’s a much more simple ECU than one of these complicated newer outboards __________________ 2020 Lifan x-pect
	1

10-15-2023, 03:47 PM	#3
Bill Hilly Join Date: Feb 2021 Posts: 947	I just turned it clockwise a little, and it improved it a whole lot. It's been raining on and off today, but I can probably fine tune it a little more.
	2