Tekken 125cc to 250cc project

HI I have recently converted my lexmoto tekken 125cc uk version to a 250cc zongshen engine . It comes to the uk very underpowered for its size . If you Google the bike it was always a 250cc with carburetor as feul source. It comes to the uk with EFI fitted FAI ecu , this would obviously not work with the 250cc engine I have fitted . The bike runs ok with my rewire to cdi and carburetor but I would love to test the nanoefi on it I think it would make a good upgrade to the 250cc version that is for sale already . Regards Dave.

Welcome @Davetenno! :wave:

The Tekken 125 looks like a great ride. If you don’t mind, why did you swap over to the 250cc?

So far I’ve enjoyed a brief experience with the CG-based 250 engine family on a Hawk 250 dual sport bike. Good cheap fun, but you’re right in that it really doesn’t have the most power per cc.

As far as compatibility with NanoEFI, most immediate issue I see is perhaps the stator’s power output. I know the Hawk came with an 8-pole stator which (if it’s the same for your Zongshen) likely won’t be enough to handle the fuel pump. I sold the bike before looking into upgrades, so that’s where I’d start now. If you have a link to documentation from Zongshen regarding your stock charging system, I’ll take a look. Thanks!

Hi , Main reason for upgrade engine was for power to weight , it was not much fun off road . when I first swapped engine I left the EFI setup that the 125cc comes with in the hope I could find some way into the ECU brains to change the timings and pulse length . FAI ecu seems to be very hard to get any info on. .
The new engine stator has no problem running the fuel pump and injector . to be honest I could probably use a lot of the stuff removed , temp sensors , TPS . oxygen sensor, I was just hoping for the chance to try and develop the ecu

Regards Dave

These are components removed from tekken 125 cc and can be used on the new set up , Fuelpump is intigrated into injector , temp sensor , throtle body with tps , and so on everthing i need except the ECU which im pretty sure the nanoefi will fit the bill .