2019 yz250f Back firing

Reset your TPS. It is set too lean from the factory.

Paw Paw

is it a real loud back fire?

Paw Paw 271 wrote:

Reset your TPS. It is set too lean from the factory.

Paw Paw

im assuming it tells you how to do that in the Manuel?

fourfourone wrote:

is it a real loud back fire?

with the race gas yes but when im just running pump just like a decel pop not to loud

Tps needs adjusted. Youll have to hook up a volt ohm meter to it to do that. I

kb228 wrote:

Tps needs adjusted. Youll have to hook up a volt ohm meter to it to do that. I

what should the reading be ??

Most OEM TPS settings are about .5v, but most find improvement at a setting of .58-.62 v.
You will to make or purchase a wiring harness for this adjustment. ( and no, this adjustment is not in the owners manual)

Paw Paw

My 19 yz250f also has a slight popping note in the exhaust when the throttle is chopped and on decel. My bike had crate damage to the mid pipe and the dealer replaced the it with a new one so I thought maybe they didn’t replace the gaskets or damaged one during the install. I am also interested in the procedure for adjusting the TPS voltage. The manual refers to a Yamaha diagnostic tool and adjusting to a specific code reading. See manual section 7-9. How are you guys measuring the TPS without the diagnostic tool?

Do a search on line for TPS test wiring for your bike. If you don't find one then you may have to make one or get the dealer to reset it for you. There are many good videos on Youtube about this.

Paw Paw

moto671z wrote:

My 19 yz250f also has a slight popping note in the exhaust when the throttle is chopped and on decel. My bike had crate damage to the mid pipe and the dealer replaced the it with a new one so I thought maybe they didn’t replace the gaskets or damaged one during the install. I am also interested in the procedure for adjusting the TPS voltage. The manual refers to a Yamaha diagnostic tool and adjusting to a specific code reading. See manual section 7-9. How are you guys measuring the TPS without the diagnostic tool?

im starting to wonder if this is a normal thing for the new 19 motor... because so far everyone that ive spoken with have the same sort of thing happening... the dealer where I bout it says to me its because of the stock muffler its cause a decal pop...

The diag tool plugs into the ecu and displays all of the sensor information.

For my bike i made a “T” shaped harness that i could plug in between the harness for the TPS. Kawasaki had detailed schematics on where to put each wire. Then i used my multimeter to read and set the voltage. I would think you can do this on your bike. Might just take some guess and check work to get the voltage reading if Yamaha doesnt have schematics in the service manual.

Heres a sketch of what i made.

Paw Paw 271 wrote:

Do a search on line for TPS test wiring for your bike. If you don't find one then you may have to make one or get the dealer to reset it for you. There are many good videos on Youtube about this.

Paw Paw

Thanks, I ended up ordering test wiring from TPS Tool. I turns out the 19 uses model 1. I did some research and saw that people are having luck with increasing the voltage into the .61 - .65 range but that was for KTM's. Is that voltage range also applicable for this bike?

kb228 wrote:

Heres a sketch of what i made.

Stock voltage was set at .48. I bumped it up to .52 for now and will try it out when it stops raining. Anyone have an idea what the voltage should be for this bike?

kb228 wrote:

Heres a sketch of what i made.

moto671z wrote:

Stock voltage was set at .48. I bumped it up to .52 for now and will try it out when it stops raining. Anyone have an idea what the voltage should be for this bike?

Found this thread through google as my 2020 WR250f is popping on decel.

What was the outcome of this?

Thanks!

The TPS setting should be between .5 volt and .62 volt as completely closed throttle. ( It will not idle with the throttle closed.) I would not go higher than about .65 volt.
Then check your WOT TPS reading. In theory it should be 5 volts at WOT, but most will not get that high right from the dealer. Then check the voltage change from closed to WOT and make sure the change is smooth through the stroke. If reading wanders or jerks as the throttle is opened the TPS is faulty.
Remember that the TPS tells the computer how to adjust the fuel delivery either more or less fuel based on the throttle opening. A pop in the exhaust on deceleration indicates a lean. The TPS adjustment can help solve this.

Paw Paw

Paw Paw

Paw Paw wrote:

The TPS setting should be between .5 volt and .62 volt as completely closed throttle. ( It will not idle with the throttle closed.) I would not go higher than about .65 volt.
Then check your WOT TPS reading. In theory it should be 5 volts at WOT, but most will not get that high right from the dealer. Then check the voltage change from closed to WOT and make sure the change is smooth through the stroke. If reading wanders or jerks as the throttle is opened the TPS is faulty.
Remember that the TPS tells the computer how to adjust the fuel delivery either more or less fuel based on the throttle opening. A pop in the exhaust on deceleration indicates a lean. The TPS adjustment can help solve this.

Paw Paw

Paw Paw

Following the manual, it appears to be in range, but not in the values that you’ve given. The pic shows 5v, and the manual says it should read between 4 and 6 volts. I just need to get a torx bit to adjust it to read slightly higher and hopefully should get rid of the popping in decel.

Fwiw the voltage doesn’t change when I open and close the throttle.

Your voltage must change or it is not functioning correctly, if connected correctly.

Paw Paw

Paw Paw wrote:

Your voltage must change or it is not functioning correctly, if connected correctly.

Paw Paw

Thanks, turns out that’s just the v5 that the tps uses, I moved the probes to the Yellow and black/blue wire and found these results, throttle at closed position shows this:




And then at wide open throttle:




Looks as though the voltage drops, is this something with the newer models? Would I then what the voltage to drop a bit lower to make it richer?

The voltage increases when working and set correctly. That is the industry standard for the TPS operation.

Paw Paw

Paw Paw 271 wrote:

The voltage increases when working and set correctly. That is the industry standard for the TPS operation.

Paw Paw

Ah right. So I still have the meter hooked up to the wrong wires?

Try turning your idel down. I was adjusting my sons 2020 yz250f idea higher and he was having backfire issues. Turned down problem solved.

Alrighty. For anyone else reading this, you slip the probes into the wires at each end of the connector. A probe doesn’t go into the middle wire.

From there you can read the tps input. Mine was .48v, shifted it to .58 then it moved to .60 when tightening.
I expect it to be a bit too rich but I’d like to see if it removes the popping on decel then maybe adjust it back until it begins to pop again, then I’ll know where the happy place is.

Thanks for your help PawPaw