I have the EJK tuner for 250cc. Do I have to send it in to reflash for the 300cc kit? The bike takes 6-7 tries to start. It fires up and dies. After several tries it starts idling. I've cranked green zone to 7 and lowered Green-Blue all the way down. It idles much better but still takes several times to start. Is it starved for fuel on start up?

 

Since no one replied with EJK specific knowledge, I'll throw this out there. Get a can of starter fluid and spray it into the air intake when starting. If it starts easily then it's a fueling issue. You still won't know if it's the tuner, pump, or injector related, but you'll know it's due to lean fuelling vs valves or some other issue.

From what I recall the EJK can support 300cc it's when you get into the bigger bores (351) that it starts to struggle. A call to EJK may help to see where the setting should be.

 

I have called them. As I suspected, the EJK doesn't do anything on start up. When the lights are running back and forth, the unit is just idling; no fuel alterations. That's why I don't think this is EJK related at all. Is there an ECU reset procedure? I'll probably unplug the battery for a few days and see.

 

Makes sense on the EJK, did it start fine prior to the tuner? Do some research on open loop vs close loop on these ecus. The ecu shouldn't be doing much either. What makes you think it's ecu vs. the many things that can cause hard starting?

 

Because of the way it behaves. I'll probably make a video. If it was a hardware issue (vacuum leak, fuel line blockage, etc), it wouldn't start at all. Yet, the bike starts but doesn't stay running until it gets a bit warmer (maybe?). If I catch it on the 2nd or 3rd power stroke with a little bit of throttle, I can keep RPMs around 2.5k for about 4-5sec. At that point you can hear an obvious change in the engine sound - that's when the EJK kicks in, I believe. At that point I can release throttle and it will idle fine. If I drop throttle before then, the bike will die again. Alternatively, I can just start it, let it fire off 3-4 cycles and die. Do that 5-6 times, and each consecutive try it fires off more cycles before dying, and, finally, it will stay running.

 

Video https://streamable.com/o2pxpn

 

EJK change injector opening time and different 250 and bigbore version is allowed offsets (bigbore open in largest intervals). So you can send EJK to reflash with new timings on install one of injectors for closer engine_volume/injector_cc_min to stock:

According to YUMINASHI original A-Type N ijnector - 220cc/min will give 1.13 ratio to stock 249cc.

For bigbore for keep in same timings you can use (Injector name; flowrate; approx engine cc accorting ratio 1.13):

Q 260cc/min 293cc

F 270cc/min 305cc

YUMINASHI special 330cc/min 372cc

Note A - "F" selling overproced by NASSERT for a klx 315cc kit, but also wased by Suzuki with pn 15710-21H00-000.

Note B - calculated flowrate just for rough comparison. In fact engine_cc and injector_cc_min with keep stock timings not linear ratio.


So you can install Q (can buy from YUMINASHI - cheaper in simple to find) or F (can buy by Suzuki by pn or from NASSERT) and it will work with 300cc with stock EFI alone and in pair with EJK for 250cc.

 

Very interesting. I didn't know one could swap the injector without a retune. Do you know what bikes Suzuki uses that injector in?
Does the larger displacement injector use the same impulse signal but simply allows for more fuel on each cycle?

 

About "without a retune" i mean "increase flowrate to fit bigbore with approx original timings for stanalone EFI or EJK for 250cc".
In case keep working EFI closed loop and keep approx same mixture in original stok timings EFI will "autotune" within reasonable limits ("big hole and loud" exchaust and open intake with "high flowrate" filter out upper EFI limits and EJK can only help to increase them).
If you _not_ disconnect oxygen sensor from exchaust EFI will go to closed loop from ~2300rpm and correct injector timing by current situation using rough AFR data from oxygen sensor.
If oxygen sensor disconnected from EFI ("O2 Bypass" installed) - EFI in fact in open loop all time and need manual retune in any engine/intake/extake mod (in this case EJK can little "overide" original injector timing curve becouse it's fixed by "O2 Bypass").
F (what used in Suzuki) acconding to NASSARET review will work with standalone EFI on 300-315cc, so you in "closed loop autotune" low timing limits.

In fact EFI work with injector by method "when and how long open". Increase flowrate will give more fuel in same open impulse from EFI.

List of Suzuki bikes with F injector, but it can be not full (use pn in any case):
GSXR1000: (Stock injector 15710-21H00-000 is 270CC/min @ 3 Bar/43 psi)
2007 GSX-R1000
2008 GSX-R1000
2009 GSX-R1000
2011 GSX-R1000 - (E3)
2011 GSX-R1000 - (E28)
2011 GSX-R1000 - (E33)
2012 GSX-R1000 - (GSX-R1000 L2 E03)
2012 GSX-R1000 - (GSX-R1000 L2 E28)
2012 GSX-R1000 - (GSX-R1000 L2 E33)
2013 GSX-R1000 - (GSX-R1000L3 E03)
2013 GSX-R1000 - (GSX-R1000L3 E28)
2013 GSX-R1000 - (GSX-R1000ZL3 E03)
2013 GSX-R1000 - (GSX-R1000ZL3 E28)
2013 GSX-R1000 - (GSX-R1000L3 E33)
2013 GSX-R1000 - (GSX-R1000ZL3 E33)
2014 GSX-R1000 - (GSX-R1000L4 E03)
2014 GSX-R1000 - (GSX-R1000L4 E28)
2014 GSX-R1000 - (GSX-R1000L4 E33)
B-KING: (Stock injector 15710-21H00-000 is 270CC/min @ 3 Bar/43 psi)
2008 B-KING (GSX1300BK)
2008 B-KING (GSX1300BKA)
2009 B-KING
2010 B-KING
HAYABUSA Gen.2: (Stock injector 15710-21H00-000 is 270CC/min @ 3 Bar/43 psi)
2008 Hayabusa (GSX1300R)
2009 Hayabusa (GSX1300R)
2011 Hayabusa (GSX1300R) - (E3)
2011 Hayabusa (GSX1300R) - (E28)
2011 Hayabusa (GSX1300R) - (E33)
2012 Hayabusa (GSX1300R) - (GSX1300R L2 E03)
2012 Hayabusa (GSX1300R) - (GSX1300R L2 E28)
2012 Hayabusa (GSX1300R) - (GSX1300R L2 E33)
KINGQUAD 400: (Stock injector 15710-21H00-000 is 270CC/min @ 3 Bar/43 psi)
2011 KingQuad (LT-A400F)
2011 KingQuad (LT-F400F)
2011 KingQuad (LT-F400FZ)
2012 KingQuad (LT-A400F)
2012 KingQuad (LT-A400FZ)
2012 KingQuad (LT-F400F)
2012 KingQuad (LT-F400FZ)

 

Update. The Suzuki injector fixed my startup issue. Thanks, 640kilobyte!
Not sure why this isn't a more popular mod. It's cheaper than EJK. And this would work with stock O2, I'm sure.