gilkeyb Posted April 13, 2015 Share Posted April 13, 2015 Hello, This (appears) to be an issue not isolated to myself. I have searched and found a couple threads asking the same questions and describing the same issue. This happens on cold mornings (Worst bellow freezing, bad below 40F). Bike cranks and starts. Idles near the "normal" level for a brief moment then drops to 700-800rpm where it runs VERY lumpy. After 10-15 seconds, RPM picks up to the normal high-idle speed of ~2500rpm. I have tried: Syncing starter valves replacing air filter replacing spark plugs enabling/disabling PC3 enabling/disabling PAIR valve syncing starter valves replacing Fast Idle Wax Unit ($$$) replacing t-stat (didn't expect this to help) charging battery/using a battery booster (still want to try a NEW) battery. I have not fixed the issue. I have seen multiple threads describing this condition but there is never a conclusion. Has anyone solved the puzzle on this issue? For the record, the bike ran PERFECT up to 18K miles. Then I tore it down for a valve inspection/adjustment. It has been doing this ever since. However, I have torn the bike down to the valves 2 more times since then (always using the service manual) and still the issue persists Brian Link to comment Share on other sites More sharing options...
ChiefGodzilla Posted April 17, 2015 Share Posted April 17, 2015 are oxy sensors affected by cold temperatures? just throwing an idea out there Link to comment Share on other sites More sharing options...
VFRpilot Posted April 17, 2015 Share Posted April 17, 2015 My bike has done this also on the few times I left it out overnight. I thought it might be moisture or condensation. Mine is a 2007 vfr 800 Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 17, 2015 Member Contributer Share Posted April 17, 2015 Inlet air temp sensor? It's a PITA to get to on the bottom of the airbox - used ones are relatively cheap on ebay. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted April 17, 2015 Member Contributer Share Posted April 17, 2015 Motorcycle troubleshooting is a form of problem solving... It is alogical search for the source of a problem so that it can be solved...it ain't about jumping to conclusions... so always eliminatethe battery first... because you find that 90% of the time it provesto be the weakest link of your bike... and so much depends on correctvoltage that it's pays to have your battery tended to a charger at alltimes... To determine the condition of an Maintenance Free battery give it arefreshing charge... wait 30 minutes... measure terminal voltage...12.8 or higher is a good battery...12.0 to 12.8 is a insufficient charge... recharge...12.0 or lower... battery unserviceable... The days of the old heavy lead acid battery are number... smart moneyis on the new light weight Lithium Iron battery like Shorai... notonly is it 5lbs lighter but doesn't require trickle charging and willnot sulfate... I also recommend Shorai's balance charger because it astwo modes one for storage and one for charging... 5th Gen VFR800 Standard Recommendation: LFX18A1-BS12 http://www.shoraipower.comShorai Balance Charger... Link to comment Share on other sites More sharing options...
gilkeyb Posted April 17, 2015 Author Share Posted April 17, 2015 Inlet air temp sensor? It's a PITA to get to on the bottom of the airbox - used ones are relatively cheap on ebay. I have the airbox off currently. So yes, i've tried connecting/disconnecting the air-temp sensor. This didn't make any positive impact on the performance. I don't think it is the culprit Motorcycle troubleshooting is a form of problem solving... It is a logical search for the source of a problem so that it can be solved... it ain't about jumping to conclusions... so always eliminate the battery first... because you find that 90% of the time it proves to be the weakest link of your bike... and so much depends on correct voltage that it's pays to have your battery tended to a charger at all times... To determine the condition of an Maintenance Free battery give it a refreshing charge... wait 30 minutes... measure terminal voltage... 12.8 or higher is a good battery... 12.0 to 12.8 is a insufficient charge... recharge... 12.0 or lower... battery unserviceable... The days of the old heavy lead acid battery are number... smart money is on the new light weight Lithium Iron battery like Shorai... not only is it 5lbs lighter but doesn't require trickle charging and will not sulfate... I also recommend Shorai's balance charger because it as two modes one for storage and one for charging... One of the first things I tried was a charged battery. I have tried eliminating the battery and running it off a battery booster only. I've tried both in parellel. I've done everything I can in terms of the battery. I also have had the battery checked by the auto shop and it checked as "okay". Link to comment Share on other sites More sharing options...
adsrox0r Posted September 22, 2015 Share Posted September 22, 2015 Realise this is an old thread and you may not read this but did you ever resolve this? Mine is back to doing it again this year and it's irritating me. I was about to try replacing the fast idle unit but seeing that you already did that and made no difference I'm not keen on spending the money and effort to remove the throttle bodies. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.