2002 VFR, 46k miles, running very poorly when hot.

[Nelso90]

For some context I was coming home from work yesterday, approximately 92F outside and I chose to take surface streets so I wasn't going too fast.  The bike got up to 223F coolant temp, fan came on as normal and cooled things down.  As I kept riding I started to notice a "popping" noise out of the intake (my flapper has been deactivated) when I would let off the throttle and slow down.  With this popping/gurgling noise would come a slight lurch...like barely noticeable.  As I kept riding, the bike seemed to start missing under part throttle.  If I whacked the throttle open it would run totally fine, but trying to maintain any cruising speed say under 10% throttle position and it just kept surging and lurching and cutting out.  I had this happen a few years ago when I lived in Indiana, and it got so bad the bike would just die and I'd have to wait for it to cool before it would even restart.  When I got home, I parked the bike and raised the revs to around 3-4k (hard to keep them steady anyway on these bikes) and it would just rev up and cut out totally, then cut back in, then out again. 

 

My first inkling on this one is maybe it's ignition coils getting heat soaked and breaking up...but before I replace $270 worth of those I figured I'd get some help. 

 

Thanks,

[Cogswell]

FWIW, Honda coilpacks are made by Denso and are of high quality.  Failures are rare.  If replacing though, those used on the VTEC engine are the same ones used on many Honda / Acura automobiles - CRV, Civic, RSX and others.  Find the Denso part number and do a search - you'll tons of them on ebay or elsewhere - you do not need to buy them from Honda Powersports. 

 

Just curious - why has your flapper valve been deactivated? 

[Thumbs]

Fuel boiling?

[Nelso90]

42 minutes ago, Cogswell said:

FWIW, Honda coilpacks are made by Denso and are of high quality.  Failures are rare.  If replacing though, those used on the VTEC engine are the same ones used on many Honda / Acura automobiles - CRV, Civic, RSX and others.  Find the Denso part number and do a search - you'll tons of them on ebay or elsewhere - you do not need to buy them from Honda Powersports. 

 

Just curious - why has your flapper valve been deactivated? 

Good to know on the coil packs.  If I end up replacing those I'll check around.  I did the intake snorkel delete and flapper valve mod because it sounded better, pure and simple.  I wanted some more intake growl.  It didn't seem to affect the bike really other than sound and it's run well for years prior. 

[BusyLittleShop]

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... 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...

Start with the battery for it's the weakest link in the whole system... 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...

[DannoXYZ]

Also coils tend to fail at high-load/high-RPMs when mixtures are denser and there's less dwell time to charge them. Trouble at low-load/low-RPMs while clean-running at higher-loads is certainly not coils.