QJ157FMI-2A (K157FMI) modding options

[Dav_kee]

Hi all,

I've been riding on my 125cc (Keeway Tx 125 EFI) for several months now and full license is on its way (along with bigger bike). However, I plan to keep my TX because... I like it. It's light and handy for every day use.

Nevertheless, I'd like to boost it a bit, so it could move more "enthusiastically".

Here's what I thought of:

- Big bore 150cc
- Oil cooler
- 14T front sprocket (stock is 13T)
- "better" camshaft and perhaps new head (if needed)

I have a few questions though, perhaps You guys could lighten me up a bit.

- Regarding Big Bore: Can I buy the larger piston only and have a stock cylinder grinded for a bigger diameter? The engine is powder coated for specific colour and standard 150cc cylinder from Aliexpress, which is not, will look like... well, not very nice.

EDIT: what is the pin diameter/length? From what I gathered, Big Bore kits for GN125 have 14mm and Keeway seems to have 13mm?? If so, the whole plan goes to the trash can.

- Regarding camshaft - there is little information about it. There are "performance" camshafts on Aliexpress, dedicated for Suzuki GN125 but I am not really convinced to them. Will they fit? What about their quality?

What about cylinder head? Do i need it?


Any advice will be welcomed. For those saying, that's not worth it - I just like doing such stuff :)



TXM125-Supermoto-GRAY.jpg

[Dav_kee]

Ok, I searched a bit more and this is what I've found - QJ157 and K157 are NOT the same engines and various kits or parts dedicated for GN125/K157FMI cannot be assembled in QJ157FMI.

Long story short, I have a 2 questions:

- Can I, by any chance, upgrade my engine to 150cc? I realise that "Big Bore" kits from aliexpress are a no-go but there IS a 150cc version of Keeway TX so maybe there is a way.

- Can I mount any "performance" camshaft? If so, where to look?

Any information will be much appreciated. @humanbeing ;)

[digitaly]

Ok, I searched a bit more and this is what I've found - QJ157 and K157 are NOT the same engines and various kits or parts dedicated for GN125/K157FMI cannot be assembled in QJ157FMI.

Long story short, I have a 2 questions:

- Can I, by any chance, upgrade my engine to 150cc? I realise that "Big Bore" kits from aliexpress are a no-go but there IS a 150cc version of Keeway TX so maybe there is a way.

- Can I mount any "performance" camshaft? If so, where to look?

Any information will be much appreciated. @humanbeing ;)

Have you found the solution please?

[Dav_kee]

Sort of.

Big bore is apparently possible (from what I gathered on Facebook groups) but I have not tried it and I don't really intend to.

What I did try however, is racing camshaft (bought on Ali, meant for Suzuki GN125). It fits perfectly but in EFI engine it will most likely not do any significant difference (unless You find a way to remap the ECU which is extremely difficult to find any information about).

I now try to fiddle with throttle position sensor in order to set the air-fuel mixture as rich as possible without crippling the engine operation which also difficult, since I only rely on service manual and allowed voltage ranges. Other than that it's blind shooting but I already have some successes (top speed rised by about 10km/h and acceleration is way more powerful) but whether it's due to new camshaft or manipulating the TPS - hard to say.