150 sx 2025 - review ?

4/25/2025 6:39am
I haven’t put my stock pipe and silencer back on to test it again but I swear my bike felt slower when I went from stock...

I haven’t put my stock pipe and silencer back on to test it again but I swear my bike felt slower when I went from stock to a full pc set up on my 2022 tc125. 

wrc777 wrote:
I felt like the PC shorty made that bike hit harder but then run out of steam quick where the stock silencer or FMF 2.1 would...

I felt like the PC shorty made that bike hit harder but then run out of steam quick where the stock silencer or FMF 2.1 would be smoother at the hit and pull harder/longer up top. Maybe the shorty just added more power and hit the limiter more quickly though?

Well, to be fair the whole point of a shorty is to gain bottom end, which sacrifices top end pull. 

TDC
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5/7/2025 3:06pm Edited Date/Time 5/7/2025 3:07pm
Tomok wrote:
Rode my 2025 150SX for the first time today. Bike is a rippa! 50/50 C12/93 Motul 800 40:1. FMF Factory Fatty with Pro Circuit Shorty. Adjusted...

20250423 142259.jpg?VersionId=KyRode my 2025 150SX for the first time today. Bike is a rippa! 50/50 C12/93 Motul 800 40:1. FMF Factory Fatty with Pro Circuit Shorty. Adjusted TPS and reset power valve. Just as fast or faster than my 2015 150SX with STIC. Hopefully she stays together.

Update: Added TSP ERM and TSP head. Noticeable power gains!

If STIC was a .115X needle tube, that is impressive. My experience is that the STIC Super X is considerably more powerful than the std PWK. 

2
5/7/2025 8:17pm
I haven’t put my stock pipe and silencer back on to test it again but I swear my bike felt slower when I went from stock...

I haven’t put my stock pipe and silencer back on to test it again but I swear my bike felt slower when I went from stock to a full pc set up on my 2022 tc125. 

wrc777 wrote:
I felt like the PC shorty made that bike hit harder but then run out of steam quick where the stock silencer or FMF 2.1 would...

I felt like the PC shorty made that bike hit harder but then run out of steam quick where the stock silencer or FMF 2.1 would be smoother at the hit and pull harder/longer up top. Maybe the shorty just added more power and hit the limiter more quickly though?

Rickyisms wrote:

Well, to be fair the whole point of a shorty is to gain bottom end, which sacrifices top end pull. 

And less back pressure & heat . That’s why they ran shorties in the nationals. 

2
burn1986
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5/7/2025 8:46pm
Here’s a few engines from 3 Dutch sand riders on the 23,24 Ktm 125.  A good sized pile of engine cases, cranks & failed electric start...

Here’s a few engines from 3 Dutch sand riders on the 23,24 Ktm 125.  A good sized pile of engine cases, cranks & failed electric start systems.  Haha 

burn1986 wrote:

Was there a photo attached? 😎

Pic wouldn’t upload, try again

Pic wouldn’t upload, try again

It’s all good 👍

The Shop

TDC
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5/15/2025 4:55pm

I just got word from the dealer that my 300SX is unfixable, bc KTM doesn't have and isn't making the power valve actuator motor. Service guy said all kinds of KTM brands customers pretty pissed right now.

So lucky to find a used 40hr actuator motor today off ebay. Close one. Need to sell it off before the next dooms day event. It's hands down the best bike I ever rode. No different than a troubled Hottie. She gotta go.

4
NSP139
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5/16/2025 11:16am
TDC wrote:
I just got word from the dealer that my 300SX is unfixable, bc KTM doesn't have and isn't making the power valve actuator motor. Service guy...

I just got word from the dealer that my 300SX is unfixable, bc KTM doesn't have and isn't making the power valve actuator motor. Service guy said all kinds of KTM brands customers pretty pissed right now.

So lucky to find a used 40hr actuator motor today off ebay. Close one. Need to sell it off before the next dooms day event. It's hands down the best bike I ever rode. No different than a troubled Hottie. She gotta go.

Does KTM actually make that motor or did they not pay the supplier that does?

FGR01
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5/16/2025 5:15pm
TDC wrote:
I just got word from the dealer that my 300SX is unfixable, bc KTM doesn't have and isn't making the power valve actuator motor. Service guy...

I just got word from the dealer that my 300SX is unfixable, bc KTM doesn't have and isn't making the power valve actuator motor. Service guy said all kinds of KTM brands customers pretty pissed right now.

So lucky to find a used 40hr actuator motor today off ebay. Close one. Need to sell it off before the next dooms day event. It's hands down the best bike I ever rode. No different than a troubled Hottie. She gotta go.

NSP139 wrote:

Does KTM actually make that motor or did they not pay the supplier that does?

Likely they get it made by an electronics company,  However, it appears specific-application enough that it is likely only available through KTM as an OEM part.

10/13/2025 8:11pm
Tomok wrote:
Rode my 2025 150SX for the first time today. Bike is a rippa! 50/50 C12/93 Motul 800 40:1. FMF Factory Fatty with Pro Circuit Shorty. Adjusted...

20250423 142259.jpg?VersionId=KyRode my 2025 150SX for the first time today. Bike is a rippa! 50/50 C12/93 Motul 800 40:1. FMF Factory Fatty with Pro Circuit Shorty. Adjusted TPS and reset power valve. Just as fast or faster than my 2015 150SX with STIC. Hopefully she stays together.

Update: Added TSP ERM and TSP head. Noticeable power gains!

I have a 2025 150 and am looking at mods. What did adjusting the TPS and resetting the power valve do for you/why was that done?

TDC
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10/14/2025 12:13pm
Smuffers wrote:

I have a 2025 150 and am looking at mods. What did adjusting the TPS and resetting the power valve do for you/why was that done?

If you mod, you need to be sure if you need new mapping or not. 

Also, there's an Italian Co that has a carb conversion kit w/ECU for the new set-up.

10/14/2025 2:39pm
Smuffers wrote:

I have a 2025 150 and am looking at mods. What did adjusting the TPS and resetting the power valve do for you/why was that done?

TDC wrote:
If you mod, you need to be sure if you need new mapping or not. Also, there's an Italian Co that has a carb conversion kit w/ECU...

If you mod, you need to be sure if you need new mapping or not. 

Also, there's an Italian Co that has a carb conversion kit w/ECU for the new set-up.

How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can account for something like that. Definitely not going to a carb as not fiddling with jets was literally why I went with this bike over a Yamaha. 

FGR01
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10/14/2025 5:15pm
Smuffers wrote:

I have a 2025 150 and am looking at mods. What did adjusting the TPS and resetting the power valve do for you/why was that done?

TDC wrote:
If you mod, you need to be sure if you need new mapping or not. Also, there's an Italian Co that has a carb conversion kit w/ECU...

If you mod, you need to be sure if you need new mapping or not. 

Also, there's an Italian Co that has a carb conversion kit w/ECU for the new set-up.

Smuffers wrote:
How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can...

How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can account for something like that. Definitely not going to a carb as not fiddling with jets was literally why I went with this bike over a Yamaha. 

The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the ECU.  Not saying that your shorty does or does not require a remap, but the ECU certainly isn't doing it.

10/14/2025 5:33pm
TDC wrote:
If you mod, you need to be sure if you need new mapping or not. Also, there's an Italian Co that has a carb conversion kit w/ECU...

If you mod, you need to be sure if you need new mapping or not. 

Also, there's an Italian Co that has a carb conversion kit w/ECU for the new set-up.

Smuffers wrote:
How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can...

How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can account for something like that. Definitely not going to a carb as not fiddling with jets was literally why I went with this bike over a Yamaha. 

FGR01 wrote:
The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the...

The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the ECU.  Not saying that your shorty does or does not require a remap, but the ECU certainly isn't doing it.

There's not an exhaust sensor, but wouldn't it sense a lean/rich condition and accommodate?

NSP139
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10/14/2025 6:26pm
Smuffers wrote:
How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can...

How would even know whether or not new mapping is required? Just slapped a shorty on there, but I have to imagine that the system can account for something like that. Definitely not going to a carb as not fiddling with jets was literally why I went with this bike over a Yamaha. 

FGR01 wrote:
The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the...

The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the ECU.  Not saying that your shorty does or does not require a remap, but the ECU certainly isn't doing it.

Smuffers wrote:

There's not an exhaust sensor, but wouldn't it sense a lean/rich condition and accommodate?

How would it know if it's lean or Rich if it's not a closed system?

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yamathumb
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10/14/2025 6:47pm

The map sensor would compensate. Some. If the engine breaths different the intake pressure is different. Fwiw

1
10/14/2025 7:46pm
FGR01 wrote:
The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the...

The EFI on TBI bikes definitely does not sense or adjust for a different muffler.    There are no sensors for that feeding back to the ECU.  Not saying that your shorty does or does not require a remap, but the ECU certainly isn't doing it.

Smuffers wrote:

There's not an exhaust sensor, but wouldn't it sense a lean/rich condition and accommodate?

NSP139 wrote:

How would it know if it's lean or Rich if it's not a closed system?

Been racing/riding for 30 years. I understand carbs and hate fiddling with them. I have no idea how these fuel injected bikes work/where the sesnors are, what is measured, or how they compensate for different conditions. 

10/14/2025 7:48pm
yamathumb wrote:

The map sensor would compensate. Some. If the engine breaths different the intake pressure is different. Fwiw

The new silencer is going to be less restrictive on the exhaust side, one would assume this would create more of a draw on the intake side. More air=more fuel=more power..... At least on the old carbed bikes. 

TDC
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10/15/2025 11:13pm
yamathumb wrote:

The map sensor would compensate. Some. If the engine breaths different the intake pressure is different. Fwiw

There is a table of fuel and timing curves available to select from in relation to atmospheric conditions, i.e. pressure. It does not recalibrate by an O2 sensor detecting rich or lean conditions.

I remember ppl seizing their bikes after installing a new pipe without checking the plug color or listen to how the bikes sounds/running.

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