Air/Fuel Ratio After Mods

[Harley rider]

I did a Yuminashi 143cc BBK,High air flow air filter,removed snorkel,high flow ,de cat exhaust to head. Put a Honda 150cc scooter injector in,as per Yuminashi BBK instruction.Actually they recommend a 140 injector. It runs rich,and I keep new plug ready,NGK CPR6EA9. NGK lower number=hotter. Answer to question yes,but change injector. If it backfires after letting off throttle on full throttle wide open run,it is too lean.BBK came with 238 cam,and I may have over gapped rings,is why it runs rich. But that might be why it hasn't blown apart. 13 tooth in front,Shinko 3/0 front rear. 60 mph plus on flat ground.

its so funny i have a close set up(except i have an outex exhaust) and i run lean with the pcx 150 injector. but here is what i found, unfortunately i have the j01, just ordered the V01 to try

but i have learned that there are multiple pcx 150 injectors with different flow rates depending on the year they fit

16450-K36-J01 flow rate about 140 cc min
16450-KXY-701 flow rate about 150 cc min
16450-K0S-V01 flow rate about 160 cc min

 

[SLO]

its so funny i have a close set up(except i have an outex exhaust) and i run lean with the pcx 150 injector. but here is what i found, unfortunately i have the j01, just ordered the V01 to try

but i have learned that there are multiple pcx 150 injectors with different flow rates depending on the year they fit

16450-K36-J01 flow rate about 140 cc min
16450-KXY-701 flow rate about 150 cc min
16450-K0S-V01 flow rate about 160 cc min

I will try to remember and look as to which one I have. The plug was loose? once,and was running (wonkey) on White Top mountain. Checked ,replaced,ran great, replaced plug after 1000 miles or so,loose again? Plug shows rich,runs GREAT! I can't kick start without the help of the starter and the (dead) battery.. Could start with hand with the Kick starter before BBK,and the cam is different and doesn't have (lobe)to assist with kick starter( I think)? 238 cam. It made a big difference in power,and I installed that before the 143cc cylinder and head. If you only do that,it makes a difference even with all else stock.

 

[dmonkey]

Depending on the cam you may be able to carry the stock decompressor over.

 

[SLO]

Depending on the cam you may be able to carry the stock decompressor over.

The only thing I would change is the suspension.Other than that it is great,if you ride where 45 mph is enforced. Day of week,time of day,and where you ride is the limits of the bike.That is why you need two bikes.

 

[haasenpfeffer_93]

Has anyone bought an EFIE recently and if so, where did you get it? Any other sources than Eagle? they’re saying out of stock: https://eagle-research.com/product/electronic-fuel-injection-enhancer-efie-device/

 

[RustyRodder]

I havent seen any other source- maybe reach out and ask when they are expected back?

 

[GonzosTrail]

its all about the air fuel ratio and the cc per minute flow rate of the injector, get that right and the ecm will cope and give you greater power. i have about 5 injectors now, but i have the benefit of knowing what my air fuel ratio is. your looking for 12.5-13 for the most power, but that does run little warm

Greetings!! Still around HR?? I read you have a way to monitor A/F ratio. Do you mind sharing set-up? EJK is building a controller for the trail (JA55) and I will be needing a way to monitor AF ratio. I am also interested on how to fool the ECU so it doesnt work against the controller. Any ideas???? I've heard about grounding the sensor and installing a Small resistor, thoughts???

Thanks
Osvaldo in Puerto Rico

 

[Harley rider]

Greetings!! Still around HR?? I read you have a way to monitor A/F ratio. Do you mind sharing set-up? EJK is building a controller for the trail (JA55) and I will be needing a way to monitor AF ratio. I am also interested on how to fool the ECU so it doesnt work against the controller. Any ideas???? I've heard about grounding the sensor and installing a Small resistor, thoughts???

Thanks
Osvaldo in Puerto Rico

so when i put in my efie device i added a narrowband af ratio sensor( i know not the best) but it can get you there. it is the Koso guage as mentioned in this youtube video.

i am not sure how to fool the ecu other than the Efie device, or an aracer ecu

 

[PAFROMQC]

Hello everyone!

New to the CT125 (june 2026), mine is a 2023 JA65.

Lots of upgrades were done, some from previous owner accessory wise but i added quite a few myself.

The CT not being engineered for a 235lbs rider, I also swap front forks springs with hd XR100 springs and replace the rear shocks with some Arashi 360mm nitrogen filled adjustable shocks, now its firm and planted, very responsive, game changer IMHO.

Most recent upgrades are NK Racing brand full exhaust system and air intake tube plus a Hurricane hiflow dry air filter. Gained midrange power, acceleration is bonified and also gained a bit of top speed, now easily hits 95km/h compared to 88km/h while 100km/h is no longer out of reach when roads are flat.

Thinking of adding ECU piggyback (ideally plug and play) to help manage increased air flow and swap injector so mixture dont get too lean (no intention of putting a cam or bigbore kit, keeping internals stock), what would you recommend for my set-up?

Comments will be greatly appreciated

 

[squeaks]

I just went through this with my 2021
And have more or less the same mods that you do.
And I just did a top end due to oil consumption and a little burning oil..
I believe it was because I kept the stock injector.
I have the efie thingy and the koso mini 3, that I believe works pretty good.
So with the efie I was showing around 12.5 but its reading does bounce all over at WOT , and I think it was just leaning out.
Research I've done said a 120cc injector, for stock, if I were you I definitely do the injector. but I did go with the 143bbk now, and a 140 cc injector.
So far I'm still getting pretty much the same ARRs as before 12.5 - 13 on the mini 3.
But I'm still breaking it in at this point so time will tell.
I'm sure others smarter than me have some input.

 

[GonzosTrail]

Hello everyone!

New to the CT125 (june 2026), mine is a 2023 JA65.

Lots of upgrades were done, some from previous owner accessory wise but i added quite a few myself.

The CT not being engineered for a 235lbs rider, I also swap front forks springs with hd XR100 springs and replace the rear shocks with some Arashi 360mm nitrogen filled adjustable shocks, now its firm and planted, very responsive, game changer IMHO.

Most recent upgrades are NK Racing brand full exhaust system and air intake tube plus a Hurricane hiflow dry air filter. Gained midrange power, acceleration is bonified and also gained a bit of top speed, now easily hits 95km/h compared to 88km/h while 100km/h is no longer out of reach when roads are flat.

Thinking of adding ECU piggyback (ideally plug and play) to help manage increased air flow and swap injector so mixture dont get too lean (no intention of putting a cam or bigbore kit, keeping internals stock), what would you recommend for my set-up?

Comments will be greatly appreciated

Greeting!

Most of what other people used to manage fuel is un-obtanium (kaplan would say) now. EFIE is not available and Aracer america has not answer my contact attempts. I made contact with dobeck performance from EJK, and they are building a controller for the Trail. Not exactly the cheapest route. Once I receive mine, I will post the results on this thread.

I too upgraded my suspension cause I ride 2up most of the time with mine. My old lady and I total a little more than 320lbs on the bike. Performs acceptable for what the bike is.

 

[squeaks]

I believe after 18k of running the efie, that it's only a help running at low rpms so does it make that much difference?
I think the Ozark garage on YouTube pretty much nailed it.
Anyway, it's kinda what I'm basing my build on, but I do have more mods than that did.
And maybe it's not relevant anymore seems how I have the older ja55 model and can't say for the ja65