Random loss in power/ stall

Hi Folks, haven't posted much since joining. Have an 06 that I bough with 25k miles, and I am now creeping up on 30k. bike has mostly run flawlessly and I am loving the sound, handling and comfort of the VFR. I haven't done any mods myself, but from what I can tell, the previous owner installed the VFRness, and removed the airbox flapper line. He also removed some of the baffling in the exhaust (can't see any packing/baffles when looking through the pipes). Bike appears to have stock plugs, coils. I run the bike on 87 octane, as the manual specifies anything better than 86 is sufficient.

Here is my problem, on several times recently when downshifting through the gears to a stop (using brakes as primary slowing method, obviously), the bike has a very erratic low idle and stalled. It almost seems like it's not running on all 4, very choppy then dies. It fires right back up and runs great. I've had this happen about 4 times in the last 5k miles of riding. Also, the other day I could feel power loss while on the throttle (3rd gear steady throttle).

Any thoughts where to start with this? I may not have provided enough info, so please let me know what I can clarify in this post.
I haven't wrenched on bikes much other than basic maintenance stuff. (oil changes, air filter) but have done some wrenching on small engines and diesel trucks. I have basic mechanics handtools, multi-meter etc..

Any help, thoughts, advice would be appreciated.

Thank you

 

Mine was doing the same thing earlier this year, dirty engine kill switch was my issue.

 

Thanks for the reply, did you just take it apart and clean the contacts?

 

Yeah, but not before I took the whole bike apart and spent days checking and cleaning everything but that. It was driving me nuts. Intermittent and hard to pin point until it cacked oot completely.

 

Wow, ok good to know. Will try that and report back. Thanks

 

Ok, they weren't that bad to begin with, but here they are cleaned up:





Will ride around for a while and report back. Thanks

 

Stalling the engine while braking can be the result of a clutch that's not fully releasing and/or idle speed set too low.

 

Ok I will check the Idle speed. How can I determine if the clutch isn't fully disengaging? The bike doesn't appear to keep "pulling" with the clutch lever pulled in.

 

might want to start using higher octane fuel because of the ethenol in US gas, uncle mentioned it to me, some articles (bickering) on google but seems best not to put ethenol in motorcycles, breaks down seals..attracts moisture 2 main reasons ive seen. doubt its your problem but just throwing that out there.

 

Thanks for the info. Unfortunately, even 93 octane (premium) in my area contains the same 10% ethanol. I run 87 during the spring/summer/fall months and fuel doesn't last long in my tank as bike is my daily driver. I will make the switch to 93 shortly to prepare for winter storage in a couple weeks.

Thanks again

 

Hi Folks, just following up from my thread last year. The issue is still there. Some additional information:
Highway RPMs do not seem affected. When up shifting at lower PRMs (around town) it seems like the bike is loosing power between gears, making the next gear very choppy. I know these bikes like the RPMs, but this never used to happen. A couple times when coming to a stop and in neutral, the RPMs dropped to around 800 RPMs but the bike didn't die, a couple blips on the throttle brought it back.

I Just change the spark plugs to see if that would help (due for a plug change). Used the OEM NGK units. Didn't help issue. I also checked battery voltage, was at 12.9 and had it on a battery maintainer during the off season. Any ideas where to go from here? Would a bad o2 sensor contribute to this problem? Was thinking of doing a DIY o2 eleminator, but only if it would help to troubleshoot. Bike has 31k and coming up on valve adjustment time. Not sure if that might contrubute to the issue or not, just throwing it out there...

Thanks in advance

 

Read this link and hope it help
http://vfrworld.com/forums/showthread.php/43671-Question-about-Fast-Idle-Wax-unit?highlight=qax+unit
Have you thought of getting a PCV and O2 eliminate to see if it cure your issue?

 

Thanks for your reply. It looks like the link you provided is for the wax-high idle unit. The high idle on the bike seems to be working, as it idles up to ~2k on colder mornings. I have thought about doing the O2 eliminator, and will probably do this next. I did not think to get a power commander yet. Just trying to fix the problem that wasn't there before

 

Is there a best method to check for vacuum leaks? Also, is there a way to test the fuel pump?

 

You might want to check the charging system to make sure that you don't have corroded connectors, etc. You can start by checking battery voltage at idle and 5000rpm. The manual states it should be >13.8V, but from what forum members have posted, it should be >14.2V and should be the same regardless of rpm.

 

Alright all, I will have some time this afternoon to start looking into a few things. Plan for tonight is:

-add seafoam treatment to gas
-Checking the battery voltage as it sits
-charging system voltage and posting findings at various RPMs.
-Check all ground wire connections. Clean and re-assemble.
-re-clean kill switch contacts - re-assemble
-Install o2 sensor eliminator (99 cent radio shack mod)

Bike is still having this problem. This morning it was sputtering out a bit also, and I'm trying to get it working well enough for a 300 mile ride this weekend.

Thanks for all of those who have helped thus far

 

I was going to suggest running some seafoam thru it for a few weeks, but I see you are already planning on doing that. Mine was occasionally falling on it's face at low rpm, especially when the engine was cold. A few tanks with seafoam seems to have cleared it right up.

 

Hi folks,

To follow up:

-add seafoam treatment to gas
DONE added half-pint to full tank. Ran the crap out of it on the way home with some full throttle blasts

-Checking the battery voltage as it sits
After sitting all night, battery read 12.92V this morning

-charging system voltage and posting findings at various RPMs.
At idle, read 14.43V. sweep up to and including 5k RPMs was right at about the same voltage 14.44V There was almost no fluctuation in voltage through the rev range

-Check all ground wire connections. Clean and re-assemble.
Found one ground under base of tank (return wire to battery) and another with 2 sets of green wires near base where tank articulated. I cleaned them, lightly sanded and applied Ox Gard then re-installed. Any additional ground wire I should check?

-re-clean kill switch contacts - re-assemble
Didn't have time to get to this yet... will do tonight

-Install o2 sensor eliminator (99 cent radio shack mod)
Installed. Haven't fired bike since this work was completed however as I pulled the battery when doing the electrical work

Any additional thoughts are appreciated

 

I don't envy you, intermittent problems are the most difficult to find. The charging system seems like it's in good shape. Only other thoughts are that you can search to see if somebody else has had similar problems or you can go through the engine diagnosis in the shop manual.

 

Thanks for the post

I've been trying to find someone with similar issue, of the ones I have located, either the problem was not identical, solved by something I have already tried, or they did not post back with the results and fix :chaingun:.