New EFI KLX250S performance testing needed.
#21
10-13-2020, 10:18 PM
Join Date: Jun 2013
Location: North Texas
Posts: 3,222
It has been determined that the stock injector fails to fuel properly at the 30hp mark - where duty cycles reach into the 90's..
Injectors have a maximum HP rating, a flow rate table, a scaling factor, and latencies. Any replacement injector must be able to perform within the parameters set into the ECM for the stock injector -since we do not have access to the ECM tables that drive the injector. The Beet 315cc injector has been proven to run well and allow 30+ hp when dyno tuned using a PCFC. Obviously, just installing a 315cc injector, without a dyno tune to accurately control it, is foolish.
Any engine that makes less than 30 hp should be able to be fueled properly with the stock injector and the PCFC or the EJK.
Note: Only fully "uncorked" 351's (lidless with full performance exhaust system (header and matching slipon)) can approach 30 hp.
Injectors have a maximum HP rating, a flow rate table, a scaling factor, and latencies. Any replacement injector must be able to perform within the parameters set into the ECM for the stock injector -since we do not have access to the ECM tables that drive the injector. The Beet 315cc injector has been proven to run well and allow 30+ hp when dyno tuned using a PCFC. Obviously, just installing a 315cc injector, without a dyno tune to accurately control it, is foolish.
Any engine that makes less than 30 hp should be able to be fueled properly with the stock injector and the PCFC or the EJK.
Note: Only fully "uncorked" 351's (lidless with full performance exhaust system (header and matching slipon)) can approach 30 hp.
Last edited by Klxster; 10-13-2020 at 10:22 PM.
#22
10-14-2020, 08:29 AM
To begin with, the engine power(hp) is derived from its torque to current RPM. Torque is derived from how much and how the fuel mixture burned out.
Injector flowrate depends only from maximum air engine consumes in single intake cycle.
Moreover, the maximum consumption usually occurs before (in RPM) the engine runs into an increasing resistance with speed at the intake and exhaust. So you can simple get situation when injector flowrate insufficient, but engine max power lower mistical "30hp".
Regarding the properties of injectors, all known possible options for replacing injectors (260cc/min, 270cc/min, 330cc/min) differ literally only in the size and number of calibration holes. There is no significant difference other than throughput due to a single base.
The KLX injector works in close-loop-cycle, except for the low ranges when open-loop-cycle used (from start-up to PAIR switch off). Replacing an injector with a suitable flowrate for the beginning of the open-cycle fuel map is quite a sufficient modification - then engine will fine at startup and low RPM , and in closed-loop cycle and the injector itself will calculate how much is needed within adequate limits of the opening time. If you do not understand what a "closed-loop-cycle" is, then consider that PCFC+Autotune is already installed, but without the possibility of manual tuning. As a matter of fact, just replacing a nozzle with a _suitable_ flowrate is good solution if you want keep stock fuel-economy lean mixture.
I will especially note an important point - the engine has a very small window when you can spray fuel to get a better mixture. Increasing operating time of the injector by several times - way to worsen the quality of the mixture (and the KLX is already sad with this) and actually waste some of the fuel (better mixture quality->faster burning->more torque->more hp in current RPM). So just installing EJK/PCFC without choosing the right nozzle not great idea.
P.S. Nassert Beet 315cc - 270cc/min and overpriced for just "brand repack"
Injector flowrate depends only from maximum air engine consumes in single intake cycle.
Moreover, the maximum consumption usually occurs before (in RPM) the engine runs into an increasing resistance with speed at the intake and exhaust. So you can simple get situation when injector flowrate insufficient, but engine max power lower mistical "30hp".
Regarding the properties of injectors, all known possible options for replacing injectors (260cc/min, 270cc/min, 330cc/min) differ literally only in the size and number of calibration holes. There is no significant difference other than throughput due to a single base.
The KLX injector works in close-loop-cycle, except for the low ranges when open-loop-cycle used (from start-up to PAIR switch off). Replacing an injector with a suitable flowrate for the beginning of the open-cycle fuel map is quite a sufficient modification - then engine will fine at startup and low RPM , and in closed-loop cycle and the injector itself will calculate how much is needed within adequate limits of the opening time. If you do not understand what a "closed-loop-cycle" is, then consider that PCFC+Autotune is already installed, but without the possibility of manual tuning. As a matter of fact, just replacing a nozzle with a _suitable_ flowrate is good solution if you want keep stock fuel-economy lean mixture.
I will especially note an important point - the engine has a very small window when you can spray fuel to get a better mixture. Increasing operating time of the injector by several times - way to worsen the quality of the mixture (and the KLX is already sad with this) and actually waste some of the fuel (better mixture quality->faster burning->more torque->more hp in current RPM). So just installing EJK/PCFC without choosing the right nozzle not great idea.
P.S. Nassert Beet 315cc - 270cc/min and overpriced for just "brand repack"
#23
10-14-2020, 10:09 PM
Join Date: Jun 2013
Location: North Texas
Posts: 3,222
@640kilobyte , it is ok.. I don't have a problem with what you believe, and think you know - most of it is wrong, but that is ok with me. Perhaps English is not your first language and most of what you wrote is simply not what you intended to mean..
At any rate, I have no need to further explore, in this thread, the minutia of injector design and functioning, closed loop fueling, open loop fueling, the variables that are involved in calculating duty cycle, etc.. However, I should tell you that you really ought to research duty cycle until you understand why HP is the limiting factor of a given injector being run at a given fuel pressure and at a given voltage.
All I do want to relay to the membership, is that use of the Beet 315cc injector is a "known quantity", as is the limits of the stock injector (approx 30hp - which few will approach or exceed)
At any rate, I have no need to further explore, in this thread, the minutia of injector design and functioning, closed loop fueling, open loop fueling, the variables that are involved in calculating duty cycle, etc.. However, I should tell you that you really ought to research duty cycle until you understand why HP is the limiting factor of a given injector being run at a given fuel pressure and at a given voltage.
All I do want to relay to the membership, is that use of the Beet 315cc injector is a "known quantity", as is the limits of the stock injector (approx 30hp - which few will approach or exceed)
Last edited by Klxster; 10-14-2020 at 10:12 PM.
#24
10-15-2020, 07:47 AM
Good - everyone will remain unconvinced. But lastly, I strongly advise you to read what the power and torque of the engine are, so as not to confuse the concept.
I'll add that the Beet 315cc injector is also sold by Suzuki under the part number 15710-21H00-000 and can often be found very cheaply.
I'll add that the Beet 315cc injector is also sold by Suzuki under the part number 15710-21H00-000 and can often be found very cheaply.
#25
10-15-2020, 03:23 PM
Join Date: Jun 2013
Location: North Texas
Posts: 3,222
Then guy and gals, there it is, a cheap way to start the process of properly fueling a "full tilt" EFI 351 build. With a dyno tune using the EJK or the PCFC, the fueling should be able to be made correct.
PCFC, as bought in the same way Jeff did for his build - @J Higgens , JH Motor Club on Youtube, https://www.kawasakiforums.com/forum...higgens-35736/
PCFC, as bought in the same way Jeff did for his build - @J Higgens , JH Motor Club on Youtube, https://www.kawasakiforums.com/forum...higgens-35736/
Last edited by Klxster; 10-15-2020 at 03:28 PM.
#26
10-15-2020, 04:26 PM
Then guy and gals, there it is, a cheap way to start the process of properly fueling a "full tilt" EFI 351 build. With a dyno tune using the EJK or the PCFC, the fueling should be able to be made correct.
PCFC, as bought in the same way Jeff did for his build - @J Higgens , JH Motor Club on Youtube, https://www.kawasakiforums.com/forum...higgens-35736/
PCFC, as bought in the same way Jeff did for his build - @J Higgens , JH Motor Club on Youtube, https://www.kawasakiforums.com/forum...higgens-35736/
#27
10-15-2020, 08:57 PM
Photos of Marcelino’s original dyno runs lost?
Hi All!
I’ve spent some hours reading through this and other threads (MCM) and your contributions including videos. You have a lot of experience, of which I have little.
It seems Marcelino’s first cam mod post has information about the standard exhaust mods and some dyno runs he did. The photos are no longer there. Can anyone on this forum help me in finding those photos? Perhaps there is an archive somewhere?
I want to keep a standard exhaust so I don’t get set upon by local ramblers and bird lovers, bless them, and also because I am now an old fart. Is it enough to mod the KLX250 muffler (seems pretty involved)? Can I simply use a KLX300 exhaust system? Does that flow better/sufficiently?
All contributions are welcome.
Marco
I’m adding my own KLX power improvement experience to Marcelino’s original thread on his camshaft modifications. Click here to jump there.
Last edited by donhoolio; 10-15-2020 at 09:23 PM.
#28
10-16-2020, 06:31 AM
stock:
after mcm:
note: last graph can be with aftermarket exchaust
I want to keep a standard exhaust so I don’t get set upon by local ramblers and bird lovers, bless them, and also because I am now an old fart. Is it enough to mod the KLX250 muffler (seems pretty involved)? Can I simply use a KLX300 exhaust system? Does that flow better/sufficiently?
Important - if you replace exchaust don't forget about:
1) Охygen sensor. Need to be installed or "simulated" using special "eliminator". Last can give to you way to manupulate fuelmap with EJK/PCFC/"air temp resistor mod"
2) PAIR system. Need only for heating catalyst to work temperature. If you exchaust dot't have it, better to remove PAIR system.
#29
10-16-2020, 09:45 AM
KEEP COOL — KEEP THE O2 SENSOR! Removing O2 sensor may cause overheating...
Thank you so much! Great work. I was unable to find these!
I’m sticking with the stock muffler or a KLX300 one for now and I may try to improve its flow while keeping the spark arrestor (too many forest fires raging in the world already) and catalyser in place.
By all means please share —I’m interested in learning all I can.
I'm not sure what PAIR means...
Users of this forum should be aware that removing the oxygen sensor, in addition to increasing pollution, may likely cause the engine to overheat. At least on EFI models. For full details please see this article and scroll down in the messages (do a search for 27/04/2019 04:52:47 UTC).
Here is what was said by that particular author/rider (apparently very experienced, knowledgeable and wise):
KLX300 system realy flow better/sufficiently. It is better to buy an aftermarket muffler than to remove the catalyst in stock.
Last can give to you way to manupulate fuelmap with EJK/PCFC/"air temp resistor mod"
2) PAIR system. Need only for heating catalyst to work temperature. If you exchaust dot't have it, better to remove PAIR system.
Important - if you replace exchaust don't forget about:
1) Охygen sensor. Need to be installed or "simulated" using special "eliminator".
1) Охygen sensor. Need to be installed or "simulated" using special "eliminator".
Here is what was said by that particular author/rider (apparently very experienced, knowledgeable and wise):
Bob said :-
Interesting things I've learned to about fuel injection on the KLX.
A popular mod is to fit an O2 eliminator, they are cheap enough so I thought "why not".
I removed the the O2 sensor, fitted the supplied bung and connected the eliminator to the plug in the wiring loom.
I was surprised to find that there was a not insignificant improvement in low and mid-range torque, the bike felt smoother and happier. I ran it round like this for a few days, there were no problems, I did notice that I was getting 5 to 10 miles less from a tank (but that could have been down to the way I was riding the bike) and that the fan was coming on sometimes.
I decided to investigate, I refitted the O2 sensor and connected a DVM set to 0-2V and taped this to the fuel tank. At this point the O2 sensor was only connected to the DVM, not to the bike [edito — plugged into the exhaust but not plugged into the wiring harness]. I found that on low throttle openings the voltage was 0.45 to 0.55V, indicating the perfect stoichiometric ratio and that on WOT (Wide Open Throttle) the voltage went to 0.8V indicating a richer mixture. This all looked very good and is in line with accepted practice.
Next I reconnected the O2 sensor to the bike (with the DVM still connected) and I was surprised to see that the voltage was 0.8 to 0.95V most of the time, indicating a rich mixture most of the time. At tick-over I saw the oscillating 0.1 to 0.8V signal that I'm used to seeing on my car, everywhere else it was 0.8V or above.
Hmmm, why is it like this? I connected my Healtech to the ECU and went for a datalogging ride. When veiwing the data with the O2 connected and with the O2 eliminator connected one measurement leapt out - the coolant temperature. I have a test run near my house, a dual carriageway of 5 miles which includes a 2 mile climb. During that run with the O2 sensor connected the coolant temperature peaked at 95C, with the O2 eliminator the coolant temperature peaked at 111C.
So I think Kawasaki set the bike up to run a rich 12.5:1 to keep it cool. These bikes are well known as cool runners and now I think this explains why I noticed the cooling fan coming on (I've never had it come on before in 9000 miles of road and trails).
Therefore I've decided to re-instate the O2 sensor and accept the standard performance.
What's really interesting is that on the forums everybody says that the O2 eliminator improves performance by enrichening the mixture when in fact it's the exact opposite. So all those people who fit a loud exhaust, remove the airbox lid and then fit an O2 elimininator assuming this device counteracts the leaning effects are in fact running their KLX250s horribly lean and horribly hot!
Live and learn.......
12/07/2019 09:58:06 UTC
Interesting things I've learned to about fuel injection on the KLX.
A popular mod is to fit an O2 eliminator, they are cheap enough so I thought "why not".
I removed the the O2 sensor, fitted the supplied bung and connected the eliminator to the plug in the wiring loom.
I was surprised to find that there was a not insignificant improvement in low and mid-range torque, the bike felt smoother and happier. I ran it round like this for a few days, there were no problems, I did notice that I was getting 5 to 10 miles less from a tank (but that could have been down to the way I was riding the bike) and that the fan was coming on sometimes.
I decided to investigate, I refitted the O2 sensor and connected a DVM set to 0-2V and taped this to the fuel tank. At this point the O2 sensor was only connected to the DVM, not to the bike [edito — plugged into the exhaust but not plugged into the wiring harness]. I found that on low throttle openings the voltage was 0.45 to 0.55V, indicating the perfect stoichiometric ratio and that on WOT (Wide Open Throttle) the voltage went to 0.8V indicating a richer mixture. This all looked very good and is in line with accepted practice.
Next I reconnected the O2 sensor to the bike (with the DVM still connected) and I was surprised to see that the voltage was 0.8 to 0.95V most of the time, indicating a rich mixture most of the time. At tick-over I saw the oscillating 0.1 to 0.8V signal that I'm used to seeing on my car, everywhere else it was 0.8V or above.
Hmmm, why is it like this? I connected my Healtech to the ECU and went for a datalogging ride. When veiwing the data with the O2 connected and with the O2 eliminator connected one measurement leapt out - the coolant temperature. I have a test run near my house, a dual carriageway of 5 miles which includes a 2 mile climb. During that run with the O2 sensor connected the coolant temperature peaked at 95C, with the O2 eliminator the coolant temperature peaked at 111C.
So I think Kawasaki set the bike up to run a rich 12.5:1 to keep it cool. These bikes are well known as cool runners and now I think this explains why I noticed the cooling fan coming on (I've never had it come on before in 9000 miles of road and trails).
Therefore I've decided to re-instate the O2 sensor and accept the standard performance.
What's really interesting is that on the forums everybody says that the O2 eliminator improves performance by enrichening the mixture when in fact it's the exact opposite. So all those people who fit a loud exhaust, remove the airbox lid and then fit an O2 elimininator assuming this device counteracts the leaning effects are in fact running their KLX250s horribly lean and horribly hot!
Live and learn.......
12/07/2019 09:58:06 UTC
Last edited by donhoolio; 10-16-2020 at 10:10 AM.
#30
10-16-2020, 11:45 AM
EJK or PowerCommanger installing between EFI and injector. It can add extra injector open time by internal map. EJK cheap and good plug-and-play solution. PowerCommanger cost more, but can use wideband oxygen sensor (sold separate) with additional hardware (also sold separate) for autotune in realtime (like closed loop in navite EFI).
"Air temp resistor mod" - old cheap hack. EFI calculate how much air engine take by inlet pressure and temperature sensors. Air sensor have negative resistance graph (lower temp - more resistance), so if you add litle more resistance it made EFI thinks "it's colder, so engine take more air, need more fuel". You can read more how it's works by googling "xt660 kev mod".
Important - installing all this request propper configuring. In all case EFI can't corect mixture (o2 sensor not works) and you can made it's dagerous lean or rich. Preffer appeal to knowledgeable people or if you want DIY - use oxygen sensor (perfect if you have wideband sensor) for understand what happens under load.
Catalyst have minimal operating temperature. If current temperature is lower, it can be "poisoned" and damaged.
At low speeds, the engine exhaust temperature is insufficient and PAIR system is used - bypass valve opens (for KLX this is an electrovalve) from the airbox to the one-way valve in the engine head to the exhaust side. Due to the injection of fresh air, the exhaust gas burns out and the catalyst warms up.
So if you don't have catalyst - remove PAIR. For complere remove need special engine PAIR plug, plug for airbox PAIR tube fitting and plug with resistor (24-26 ohm according manual) to electrovalve harness side connector.
Note: then PAIR valve open (lower approx 2300rpm) oxygen sensor (installed after valve) always shows lean mixture.
The engine independently keep coolant temperature "near optimal" in the cylinder using a thermostat. It always stays around ~ 90 degrees at sensor engine side - this is normal. The temperature sensor is primarily for understanding when to end the warm-up cycle (note that the engine idle rpm at rich mixture on a cold start) and turn warning light at overheat (I don't remember exactly, but it seems to be over 105 degrees). As for the fact that KLX EFI is able to do something with mixture when overheating I have not heard.
Also some note: if you use native oxygen sensor you need to know - it's narrow band type and can show in fact only "lower, equal, more 14.7". Oscillating is normal - it's depends at exchaust "pulse".
"Air temp resistor mod" - old cheap hack. EFI calculate how much air engine take by inlet pressure and temperature sensors. Air sensor have negative resistance graph (lower temp - more resistance), so if you add litle more resistance it made EFI thinks "it's colder, so engine take more air, need more fuel". You can read more how it's works by googling "xt660 kev mod".
Important - installing all this request propper configuring. In all case EFI can't corect mixture (o2 sensor not works) and you can made it's dagerous lean or rich. Preffer appeal to knowledgeable people or if you want DIY - use oxygen sensor (perfect if you have wideband sensor) for understand what happens under load.
Catalyst have minimal operating temperature. If current temperature is lower, it can be "poisoned" and damaged.
At low speeds, the engine exhaust temperature is insufficient and PAIR system is used - bypass valve opens (for KLX this is an electrovalve) from the airbox to the one-way valve in the engine head to the exhaust side. Due to the injection of fresh air, the exhaust gas burns out and the catalyst warms up.
So if you don't have catalyst - remove PAIR. For complere remove need special engine PAIR plug, plug for airbox PAIR tube fitting and plug with resistor (24-26 ohm according manual) to electrovalve harness side connector.
Note: then PAIR valve open (lower approx 2300rpm) oxygen sensor (installed after valve) always shows lean mixture.
Users of this forum should be aware that removing the oxygen sensor, in addition to increasing pollution, may likely cause the engine to overheat. At least on EFI models. For full details please see this article and scroll down in the messages (do a search for 27/04/2019 04:52:47 UTC).
Here is what was said by that particular author/rider (apparently very experienced, knowledgeable and wise):
Here is what was said by that particular author/rider (apparently very experienced, knowledgeable and wise):
Also some note: if you use native oxygen sensor you need to know - it's narrow band type and can show in fact only "lower, equal, more 14.7". Oscillating is normal - it's depends at exchaust "pulse".