RX3 running issues

elevatorman · 05-26-2018, 07:17 PM

I have a 2015 RX3 that recently developed issues. I rode it around 20 miles
with everything feeling normal then it started feeling roughness and flat in
the rpm range of 4500 to 5500. when pushed through the flat spot it then
picks up to normal revs. I've adjusted valves, replaced spark plug, air filter
and fuel filter. Below 4500 rpm it feels good but flatness creeps in just
beyond. Any thoughts from the RX3 group?

Working_ZS · 05-26-2018, 08:26 PM

Quote:

Originally Posted by elevatorman

Below 4500 rpm it feels good but flatness creeps in just
beyond. Any thoughts from the RX3 group?

Flatness? Do you mean a drop in power? Or a misfire, then it smooths out? Is this while the bike is sitting in neutral and being revved or while riding it?

I ask because I seldom, if ever run at 4500 RPM. The bike likes to sit at 6000 - 8000 RPM for best performance. If I am approaching 5000 RPM, I downshift a gear to get back to 6000 RPM or above. Every once in awhile, I may lug it that low but normally 5000 RPM is my floor.

Some possibilities that I can think of off the top of my head, and not necessarily in the most likely order:

1. Fuel pump issue.

2. Loose spark plug wire connection, sensitive to engine vibes.

3. Intermittent electrical contact issue in the ignition system somewhere, again sensitive to engine vibration.

4. Vacuum leak somewhere, allowing unmetered fresh air into the fuel induction system. Try spraying starting fluid (ether) around the intake while revving it in the problem RPM range.

Citroenjunkie · 05-27-2018, 08:41 PM

My bike barely runs below 5500. My ride to work is relatively downhill but even so if I am rumbling along in 6th gear at around 60km/h and about 4000 revs I have to chage down at least two gears before I can open the throttle and get a response. If I do try to make the bike pull below 5000 it chugs and splutters pityfully. Change down to fourth, roll on the throttle and it's all go.

Once the engine is at operating temperature rev it, that's why it has a rev counter and short gearing. It is also much smoother over 6000. At 8000 I can almost see in the mirrors!

I'd be suprised if any 250 single made pulls strongly at such low revs. If you don't like revs make sure you keep away from the smaller Japanese multi cylinder bikes. My CB400SF didn't go at all until about 8000 and pulled happily right up to 14000, all day!

The guys at CSC did over 5000 miles with the original bikes and wrote about it at length - 5000 at 8000 the had no hassles at all. I think the 250 motors will outlive us all.

Jay In Milpitas · 05-28-2018, 01:09 PM

Quote:

Originally Posted by elevatorman

I have a 2015 RX3 that recently developed issues. I rode it around 20 miles
with everything feeling normal then it started feeling roughness and flat in
the rpm range of 4500 to 5500. when pushed through the flat spot it then
picks up to normal revs. I've adjusted valves, replaced spark plug, air filter
and fuel filter. Below 4500 rpm it feels good but flatness creeps in just
beyond. Any thoughts from the RX3 group?

Had you done anything prior to the roughness beginning?
Put new gasoline in the tank?
Valve adjustment recently? I ask that because there have been more than a couple instances where the owner adjusted valves and didn't secure one lock nut, allowing the adjustment to change & mess things up.

elevatorman · 05-28-2018, 06:26 PM

Definite drop in power that came on suddenly in this rpm range.
Revs strong when not under load but loses power when on road.
I understand comments about low rpm however this is a new symptom.
Additionally I have a 2016 RX3 to compare to and it's not anywhere near this
feeling. I can start swapping components from one to the other as soon as I
get some idea of what to change out. Comments about valves are considered
but this symptom came on suddenly with nothing done and the bike was running good. after adjusting valves the bike runs better from idle to 4500
however that is where it loses power. after pushing through 5500 it takes off.
Around town riding on either bike for me is always between 4500 and 6000
rpm. I run fuel from airport,93 octane super unleaded with Lucas treatment.

2LZ · 05-29-2018, 10:27 AM

Imagining that your valves are set to spec and that your plug, etc...are all known good, I'd suggest cleaning and tightening your battery terminals. These bikes s can do funky things if a terminal worked loose.

NzBrakelathes · 05-29-2018, 07:02 PM

Quote:

Originally Posted by elevatorman

I have a 2015 RX3 that recently developed issues. I rode it around 20 miles
with everything feeling normal then it started feeling roughness and flat in
the rpm range of 4500 to 5500. when pushed through the flat spot it then
picks up to normal revs. I've adjusted valves, replaced spark plug, air filter
and fuel filter. Below 4500 rpm it feels good but flatness creeps in just
beyond. Any thoughts from the RX3 group?

I have had a couple of these bikes run poorly in closed loop (6000 rpm and below there abouts)
Both cases were issues with MAP sensor, 1 had a bad plug and corrosion at the connection the other a bad sensor.
Check on the Diag PC and check air temp and air pressure etc.
Or just do a qiuck swap between bikes as these are both in all years the same.
Small hex bolt and pull the little black sensor out etc

elevatorman · 06-26-2018, 12:50 PM

Update on issues with this motorcycle.
I've swapped ecu from one bike to another which made the 2015 run correctly.
However 10 miles into ride it seemed to be starved for fuel.
After that I disconnected the o2 sensor to run open loop and everything
works great again.
Then I installed the suspect ecu in the 2016 RX3 and had it running poorly.
Once again I disconnected o2 sensor and it runs good also.
Has anyone tried using o2 sensor available from auto supply?
CSC is very proud of their sensor. any feed back will be appreciated.

DanKearney · 06-27-2018, 04:17 PM

Any chance you've got an air leak in the intake train at some point?

Perhaps when you hit that 4,500 rpm range the leak worsens at that point, causes a lean condition which the F.I. computer then needs to adjust, resulting in the flat range?

Cheers,

Dan K.

NzBrakelathes · 06-27-2018, 08:14 PM

Quote:

Originally Posted by elevatorman

Update on issues with this motorcycle.
I've swapped ecu from one bike to another which made the 2015 run correctly.
However 10 miles into ride it seemed to be starved for fuel.
After that I disconnected the o2 sensor to run open loop and everything
works great again.
Then I installed the suspect ecu in the 2016 RX3 and had it running poorly.
Once again I disconnected o2 sensor and it runs good also.
Has anyone tried using o2 sensor available from auto supply?
CSC is very proud of their sensor. any feed back will be appreciated.

Please try this
Swap the black MAP sensor on the manifold, they seem to be common to give issues.

elevatorman · 07-03-2018, 03:43 PM

I finally solved the issue with my RX3. After installing a new o2 sensor and
doing reboot on the ECU it all came back to life.
When I asked about sensor from auto parts store I got no answer however
I found that a Bosch sensor was a direct fit up and works perfectly.
For people experiencing such issues I've found out that the Delphi FI goes
open loop after about 80% throttle. It all makes sense now.

2LZ · 07-03-2018, 05:10 PM

Quote:

Originally Posted by elevatorman

I found that a Bosch sensor was a direct fit up and works perfectly..

Is there an available part #?? I'd like to keep one handy. My white RX is still exhibiting some oddities on occasion. Blue one is perfect, as always.

Jay In Milpitas · 07-04-2018, 01:46 PM

Years back I posted some info from a now defunct forum that told of one owner clearing up a poor running issue on his RX3 by removing and cleaning the MAP sensor.

Depending on how much slack you have in your wire harness, you may not need to unplug it. Remove the fastener, wipe the surface with a clean cloth/paper towel, use carb cleaner sparingly if necessary to remove any residue.

If I recall, the issue was at idle as well as a stumble in mid-range.

elevatorman · 07-05-2018, 10:15 AM

The Bosch sensor that I installed on my RX3 was part number 15703.
Difference was in the wiring colors but a check of what does the various functions it was all correct. Another difference was the wire length is about
4 inches shorter but the original sensor had wire doubled over then tie wrapped
in place. All together it works correctly and saved me time and money.

2LZ · 07-05-2018, 12:31 PM

Quote:

Originally Posted by elevatorman

The Bosch sensor that I installed on my RX3 was part number 15703.
Difference was in the wiring colors but a check of what does the various functions it was all correct. Another difference was the wire length is about
4 inches shorter but the original sensor had wire doubled over then tie wrapped
in place. All together it works correctly and saved me time and money.

Thanks a bunch. I just ordered one to check out on my white bike. Cheap enough.

05-26-2018, 07:17 PM	#1
elevatorman Join Date: May 2017 Location: knoxville, tn Posts: 25	RX3 running issues I have a 2015 RX3 that recently developed issues. I rode it around 20 miles with everything feeling normal then it started feeling roughness and flat in the rpm range of 4500 to 5500. when pushed through the flat spot it then picks up to normal revs. I've adjusted valves, replaced spark plug, air filter and fuel filter. Below 4500 rpm it feels good but flatness creeps in just beyond. Any thoughts from the RX3 group?
	0

05-27-2018, 08:41 PM	#3
Citroenjunkie Join Date: Feb 2017 Location: Dannevirke, New Zealand Posts: 47	Little engines - mine too My bike barely runs below 5500. My ride to work is relatively downhill but even so if I am rumbling along in 6th gear at around 60km/h and about 4000 revs I have to chage down at least two gears before I can open the throttle and get a response. If I do try to make the bike pull below 5000 it chugs and splutters pityfully. Change down to fourth, roll on the throttle and it's all go. Once the engine is at operating temperature rev it, that's why it has a rev counter and short gearing. It is also much smoother over 6000. At 8000 I can almost see in the mirrors! I'd be suprised if any 250 single made pulls strongly at such low revs. If you don't like revs make sure you keep away from the smaller Japanese multi cylinder bikes. My CB400SF didn't go at all until about 8000 and pulled happily right up to 14000, all day! The guys at CSC did over 5000 miles with the original bikes and wrote about it at length - 5000 at 8000 the had no hassles at all. I think the 250 motors will outlive us all.
	1

05-29-2018, 10:27 AM	#6
2LZ Join Date: Mar 2010 Location: Volcano, Ca Posts: 7,063	Imagining that your valves are set to spec and that your plug, etc...are all known good, I'd suggest cleaning and tightening your battery terminals. These bikes s can do funky things if a terminal worked loose. __________________ "Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350
	2

06-27-2018, 04:17 PM	#9
DanKearney Join Date: Jul 2009 Posts: 216	Any chance you've got an air leak in the intake train at some point? Perhaps when you hit that 4,500 rpm range the leak worsens at that point, causes a lean condition which the F.I. computer then needs to adjust, resulting in the flat range? Cheers, Dan K. __________________ Dan Kearney - Black Hawk, Colorado, USA Dan's Motorcycle Blog - "Lost? I'm not lost. I'm just exploring. . ."
	0

07-03-2018, 03:43 PM	#11
elevatorman Join Date: May 2017 Location: knoxville, tn Posts: 25	Problem found I finally solved the issue with my RX3. After installing a new o2 sensor and doing reboot on the ECU it all came back to life. When I asked about sensor from auto parts store I got no answer however I found that a Bosch sensor was a direct fit up and works perfectly. For people experiencing such issues I've found out that the Delphi FI goes open loop after about 80% throttle. It all makes sense now.
	5

05-28-2018, 06:26 PM	#5
elevatorman Join Date: May 2017 Location: knoxville, tn Posts: 25	Definite drop in power that came on suddenly in this rpm range. Revs strong when not under load but loses power when on road. I understand comments about low rpm however this is a new symptom. Additionally I have a 2016 RX3 to compare to and it's not anywhere near this feeling. I can start swapping components from one to the other as soon as I get some idea of what to change out. Comments about valves are considered but this symptom came on suddenly with nothing done and the bike was running good. after adjusting valves the bike runs better from idle to 4500 however that is where it loses power. after pushing through 5500 it takes off. Around town riding on either bike for me is always between 4500 and 6000 rpm. I run fuel from airport,93 octane super unleaded with Lucas treatment.
	0

06-26-2018, 12:50 PM	#8
elevatorman Join Date: May 2017 Location: knoxville, tn Posts: 25	Update on issues with this motorcycle. I've swapped ecu from one bike to another which made the 2015 run correctly. However 10 miles into ride it seemed to be starved for fuel. After that I disconnected the o2 sensor to run open loop and everything works great again. Then I installed the suspect ecu in the 2016 RX3 and had it running poorly. Once again I disconnected o2 sensor and it runs good also. Has anyone tried using o2 sensor available from auto supply? CSC is very proud of their sensor. any feed back will be appreciated.
	0

07-04-2018, 01:46 PM	#13
Jay In Milpitas Join Date: Jul 2015 Location: Milpitas, CA. USA Posts: 775	Years back I posted some info from a now defunct forum that told of one owner clearing up a poor running issue on his RX3 by removing and cleaning the MAP sensor. Depending on how much slack you have in your wire harness, you may not need to unplug it. Remove the fastener, wipe the surface with a clean cloth/paper towel, use carb cleaner sparingly if necessary to remove any residue. If I recall, the issue was at idle as well as a stumble in mid-range. __________________ Horse holder at Madame Orr's House.
	0

07-05-2018, 10:15 AM	#14
elevatorman Join Date: May 2017 Location: knoxville, tn Posts: 25	O2 Sensor The Bosch sensor that I installed on my RX3 was part number 15703. Difference was in the wiring colors but a check of what does the various functions it was all correct. Another difference was the wire length is about 4 inches shorter but the original sensor had wire doubled over then tie wrapped in place. All together it works correctly and saved me time and money.
	1