2025 TBI 300sx nothing but issues

Throwing any codes? Try another ECU…check wiring for pinch and/ or connections…I have had 2 300SX”s…a total of 200hrs between the 2 of them…. Never had any issues….I replace in line fuel filter every 20hrs, OEM spark plug and powervalve reset every 25-30hrs….top ends at 100hrs…have never had reed block apart on either machine….

When was the ECU reflash done?

Bogging and poor running can be a sign of a bad crank case pressure sensor.   The electronic power valve could also need reset which would lead to poor running.  

Are you getting any codes? 

Could be the reflash, contact motox and see if they can restore it back to stock...as a test.

The mapping might be too aggressive for your conditions, most of these bikes run different from each other right out of the crate.

A reflash doesn't always work for every bike across the board, yes it ran good for a short time but then it caused adverse affects....hard to know for sure. starting back from stock eliminates the reflash, then you'll know.

You might be better off to go with a tsp erm, you can control mapping, build your own maps, download tsp maps and toggle between stock and alternative maps.

Plus it has a host of other features, data logging, code reading and clearing, pv adjustments etc...

As a lot of things are not OEM on your bike I would go back to those specs and start from there: 

proper TPS learning (performed by a dealer)

proper exhaust valve motor learning 

run standard BR8ES plug (saves you money too)

run (best available) standard pump gas (saves you money too)

check deck height (x-distance 0,00 to 0,10) and exhaust valve height (z-distance 48,00) just to be sure the hardware side is OK

check crank pressure sensor (but I guess it´s okay)

exhaust and reeds should not play such a major role

Then I´m pretty sure you get this thing running properly and will enjoy riding it.

The TBI has two identical sensors, one used as ccps and one as ambient air.    You can swap them to test, and if the poor running goes away its due the sensor.

Further troubleshooting:  When did the poor running start? 

Before or after ECU reprogram?  Did the bike run well/no symptoms after the ECU reprogram? 

Before or after the reed block replacement?  Same question as above, did it run well/no symptoms after the reed block replacement?

A great result for you!

Of the - an estimate - perhaps 40 to 50 people I've known with the 2 variants of EFI 'KTGroup' 2ts, I've only seen around 2 with heartbreaking problems. 

And, they were truly heartbreaking for the poor buggers. 

The TPS connectors and the CC pressure sensors were (slightly) common, but, generally easily sorted, once the 'cures' were known.

Hope it stays well running, after your problems.

Glad you solved your issue! The only time I use a pressure washer is at the races, and I aim low with the high pressure. Mainly use my garden hose to clean bike….and never spray water at switches on handlebars…or connectors for TBI…. I have never had an issue with both of my 300SX”s….stock these bikes are fun, with a tune and gearing for your riding….these bikes are unbelievable….I go from high rpm Mx track to tight woods riding with just a pipe swap and selecting the a different map…

How is the performance with the TSP ERM versus the MotoX Mapping?

You could use fluid film on all electrical connectors.

Now... There's a controversial debate as to which is better, fluid film or di-electric grease.

I did some real world research on this topic and most mechanics in the salt belt only use fluid film, for a few reasons.

Di-electric grease, is non conducting and many techs have said it caused more electrical issues by interfering with connectivity, especially low voltage circuits.

Now, I've not had any issues with digrease but after talking to a guy that specializes in vehicle electrical issues....he convinced me to switch to fluid film and it's been fine.

Thanks!  I’m likely going to pull the trigger this week on an ERM. 

Yup, need more electronics on dirt bikes