Troubleshooting what happened after changing spark plugs

[TenereStreets]

I changed the spark plugs before a track day and all was well then. However after the track day I noticed the bike would have some initial hesitation at low RPM (2-3k) when rolling on throttle from off-throttle. This didn’t happen all the time though. I figure something went wrong with the new spark plugs. I did drop one prior to installing but did correct the gap. Changed the plugs with new ones last night and same problem when riding today. So I thought maybe it’s the Powercommander. I took that off and the O2 Optimizer and so far the hesitation seems fixed but now the bike won’t go full throttle. Also accelerates normally part-throttle until around 5k RPM then the power drops. I just checked that I reconnected everything last night and all seems connected. I do have Arrow headers on an otherwise stock bike. I can’t imagine headers would cause this. Any suggestions? TPS?

 

[Dogdaze]

Could be a bad coil? Not revving up to full throttle is associated with poor spark and the coil would be next after plugs... problem is that there are four.

 

[Checkswrecks]

Well, it sounds like you could have affected the ignition with the plugs and the coils/caps, then the fuel/air ratio with both the O2 optimizer, PC, and pipe. Running at top rpm continuously on the track is also not what these tall engines were designed for, so hopefully you didn't skip a tooth on a cam. If you have a local dyno with an oscilloscope and exhaust analyzer (that's relatively cheap) it shouldn't be too hard to isolate but assuming you do not . . .


Wait to see what a few other arm chair experts think, but at this point, my thoughts would be to:


1. Re-seat the primary electric connector on each coil and then re-seat each on the respective plug. Also reseat the O2 sensor connector. Run it to see if anything changes.


2. Try a single run without the air filter to see at what rpm it loses power and my guess is that it will be worse. The pipe flows air easier so without the filter it runs ever so slightly leaner as well.


3. Reconnect the PC and run it. Then try it with the O2 optimizer.


4. Check the compression.


5. If it were easier to get to the cams at this point, I would suggest checking their timing. But if it were my bike at this point I'd probably change out the O2 sensor first. It'll cost you something like $85 but the symptoms just feel right for it and I'd rather spend the money before losing the time required to get to the valves.


6. At this point the next step would be checking the valve timing and since you are there, the gaps.


Good luck. Report back on what you find.

 

[Don in Lodi]

First off, Not a Race Bike... What year? Has the cam chain tensioner been upgraded if it's a pre-14. Sounds like it may have jumped a tooth. Luckily not more than one.

 

[TenereStreets]

Thanks for the suggestions. I’ll try some and hopefully the problem gets fixed without taking it in to the dealership.
It’s a 2014 and definitely not a race bike ::001::

 

[TenereStreets]

Finally troubleshot the problems I was having and they were due to some bonehead moves by yours truly. The 2nd issue of the bike accelerating normally part-throttle until around 5k RPM then the power dropped was because the fuel line unknowingly got pinched. I figured out the 1st issue of initial hesitation at low RPM (2-3k) when rolling on throttle from off-throttle after removing the Powercommander and then the bike ran fine. In talking with Dynojet tech support they mentioned reinstalling the firmware and reloading the map. Then I asked about the “Rev-extend” option and the response was that that doesn’t do anything for our bike and that strange thing happen when enabled. I remembered enabling it prior to the track day. So I still reinstalled the firmware, reloaded my custom map and made sure the Rev-extend box was unchecked. Took the bike for a ride earlier and was unable to reproduce any of the problems I was having earlier.

 

[ace50]

Finally troubleshot the problems I was having and they were due to some bonehead moves by yours truly. The 2nd issue of the bike accelerating normally part-throttle until around 5k RPM then the power dropped was because the fuel line unknowingly got pinched. I figured out the 1st issue of initial hesitation at low RPM (2-3k) when rolling on throttle from off-throttle after removing the Powercommander and then the bike ran fine. In talking with Dynojet tech support they mentioned reinstalling the firmware and reloading the map. Then I asked about the “Rev-extend” option and the response was that that doesn’t do anything for our bike and that strange thing happen when enabled. I remembered enabling it prior to the track day. So I still reinstalled the firmware, reloaded my custom map and made sure the Rev-extend box was unchecked. Took the bike for a ride earlier and was unable to reproduce any of the problems I was having earlier.

Maybe you should have mentioned that in OP.................. ::009::

 

[Checkswrecks]

Finally troubleshot the problems I was having and they were due to some bonehead moves by yours truly. The 2nd issue of the bike accelerating normally part-throttle until around 5k RPM then the power dropped was because the fuel line unknowingly got pinched. I figured out the 1st issue of initial hesitation at low RPM (2-3k) when rolling on throttle from off-throttle after removing the Powercommander and then the bike ran fine. In talking with Dynojet tech support they mentioned reinstalling the firmware and reloading the map. Then I asked about the “Rev-extend” option and the response was that that doesn’t do anything for our bike and that strange thing happen when enabled. I remembered enabling it prior to the track day. So I still reinstalled the firmware, reloaded my custom map and made sure the Rev-extend box was unchecked. Took the bike for a ride earlier and was unable to reproduce any of the problems I was having earlier.

I'd hate to tell how many things I forgot. Thanks for sharing.
::008::

 

[Don in Lodi]

I usually lead off with 'what did you last do to your machine' on these threads. Glad you found it. ::008::