Bike decelerates with and without engine light on


Love Enigma

New Member
Heya,
So, I take care of my baby and had a full body tune up about a year about (~10k miles I think? @38k). She has just started to do this weird thing where if I am riding (mostly freeway since that is 95% of my commute) the engine light will pop on for a second and the bike decelerates about 200-400 rpm. No reving, no electrical power loss, nothing.

She was only doing it once every 15+ miles or and I do a full check up; checked the diagnostic codes and nothing. It was good for a few days after we replaced the headlight bulb, but then she started doing it. Last night, it happened every 2-3 seconds for 1/2 a second (pulsing) at around 6k rpm and above abut 3 minutes into the ride. The engine light did not come on, but it did when it happened for the 1 second.

I pulled off and waited a bit. Nothing on diagnostic codes. Then rode home at <5k rpm (about 10 minutes) and she did not do it again. Here is what I have noted/checked:

  • Oil level- good. Last change 2 month ago/still fresh.
  • Chain: newer xring, decently maintained, but could be better. First non-oring chain. Put on about 2 months ago.
  • Battery: 12.56v
  • No electrical dimming (lights, etc)
error codes in diagnostic mode and all within recommended levels.

Noted when it has happened:
  • Not in a standard pattern (I.e. Not every ride nor at a specific duration. Will go days before happening again.)
  • With/without kill switch to shut off. When used kickstand it seemed better, but it was just false hope.
  • RPM: inconsistent, but typically >5k rpm (in any gear. Happened in 2nd yesterday) however, it has done it at lower rpms.
    Loses about 200-400 rpm, depends on the duration.
  • Heat: inconsistent. Has happened when cool, 168*, 179*, and High
  • Mph: inconsistent. Originally noted about 65mph and above, but happens at maybe 10mph.
  • No issues with throttle, clutch, breaks lines.
  • Smell: kind of wonky; almost like a burned asphalt/plastic, but it has been really hot here and could legit be the asphalt.
  • Sound: just decelerates, does not rev. No sputtering.
    It kind of felt like my chain caught for a second last night.
  • No fluid leakage
  • No abnormal heat areas.

About the bike:
-2009 FZ6R
-No engine modifications or farkles or any kind. Still pretty standard... even the exhaust.
-No previous issues and none noted during check up 1.5 years ago. Was still all in alignment at 55k? 65k? (have to check maintenance log to be sure it was at that mileage marker).
-Current Mileage: 46k

What I've done:
- Cleaned up connectors:
- Fuses, relay assembly, battery connectors, kill switch, regulator...
- 9/5 Replaced battery

Thoughts?

TIA!!
 
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Just_Jim

Member
That's sounds more like an electrical issue than a mechanical one. Maybe a loose/broken/dirty connector.
 

Love Enigma

New Member
That's sounds more like an electrical issue than a mechanical one. Maybe a loose/broken/dirty connector.
Thanks for the response! I appreciate your insight.

We went through a lot of the wiring to clean up connectors when we changed the headlight bulb, (after it was already doing this), but I will go through her again and update as necessary. =p
 

BluePill

Member
Your battery voltage looks bad. A fully charged 12 volt battery at rest (bike turned off) should be 12.8 (+/- 0.2) volts.

With the bike running, you should see 14.0 (+/- 0.4) volts.

If the voltage while riding falls below about 11.0 volts it can cause solid state systems in the bike to cut out. Sometimes the battery can have an intermittent short circuit causing the same effect.


If your battery tests bad, do yourself a favor and stay away from auto parts store batteries. Buy a genuine Yuasa from a good internet source. I buy through Amazon and have had good luck, and quite a bit cheaper than the dealership.

I just noticed Summit Racing has a good price:

https://www.summitracing.com/parts/ysa-yt12b-bs
 
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Love Enigma

New Member
Your battery voltage looks bad. A fully charged 12 volt battery at rest (bike turned off) should be 12.8 (+/- 0.2) volts.

With the bike running, you should see 14.0 (+/- 0.4) volts.

If the voltage while riding falls below about 11.0 volts it can cause solid state systems in the bike to cut out. Sometimes the battery can have an intermittent short circuit causing the same effect.


If your battery tests bad, do yourself a favor and stay away from auto parts store batteries. Buy a genuine Yuasa from a good internet source. I buy through Amazon and have had good luck, and quite a bit cheaper than the dealership.

I just noticed Summit Racing has a good price:

https://www.summitracing.com/parts/ysa-yt12b-bs
Hit,
Thanks for the info. I actually misspoke and double checked it today. It sits at 12.56v
 

adazine

Premium Member

TN6R

Member
I would say it’s a battery issue. I’ve had a couple very strange issues with my bike in the past and both times it ended up being a battery problem. One time the battery was low in voltage and the other time the terminals needed to be tightened.
 

Love Enigma

New Member
Yeah, I'm going to swap the battery and see what happens. =] Thanks for the info BluePill!

Note: Battery swapped today 9/5/18
 
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