2007 Bonnie Running Problem

[rmiles]

Started out yesterday morning just fine. Rode across the state of Ohio,then back home. All total of about 400 miles. At highway speeds, the bike was running great, but when I would exit, I started noticing a little back fire. By the time I made it home the bike was missing and cutting out to almost a stall. It almost made a sound as if it were sucking in air.
I started the bike this morning and it`s running and sounds fine. Anyone out there had this experience? I`ll be taking it to the shop for the 6000 service but would like to have a little better understanding of what it may be.
I am in no way a mechanic and any help would be greatly appreciated!!

 

[paulSF]

Check the little black rubber caps on the vacuum lines from the carbs. I had one fall off and the symptoms were exactly the same.

 

[rmiles]

Check the little black rubber caps on the vacuum lines from the carbs. I had one fall off and the symptoms were exactly the same.

Unfortunately that was my first guess but all were intact. I think there are only 4? Thinking of removing float bowls making sure there is no foreign matter blocking flow. Thanks for the advice!

 

[Bossman]

You most likely have a lean backfire that caused by an intake leak. The engine has high vacuum under deceleration, which will magnify the leak. If you had a partially clogged jet, the bike would most likely have a flat spot somewhere in the acceleration curve. Warm the engine for a couple minutes, then spray carb cleaner (not starting fluid) between the head and carb boots and between the carbs and air box boots. If you have a leak, the engine will either speed up or slow slightly, depending on how bad it is. If nothing seems to be wrong, let the engine cool down, dampen you hands with cold water, start the engine and feel all of the exhaust connections to check for an exhaust leak, which can also cause the problem you are describing. Good luck!

 

[Aussie_T100]

Warm the engine for a couple minutes, then spray carb cleaner (not starting fluid) between the head and carb boots and between the carbs and air box boots. If you have a leak, the engine will either speed up or slow slightly, depending on how bad it is.

Good advice except that an air leak upstream of the carbies (ie. the airbox boots) will not cause the engine to run lean or miss however it will allow unfiltered air into the engine. Only air leaks between the carbies and the engine will cause poor running.

I would also check fuel tank venting as the symptoms sound like fuel starvation and the bike did run fine again after sitting overnight.

 

[rmiles]

Check the little black rubber caps on the vacuum lines from the carbs. I had one fall off and the symptoms were exactly the same.

Thanks to all for the sound advice, found the problem this morning. It was the rubber vacuum caps. Started checking for intake leak with starting fluid and noticed cracks on one of the caps. When I tried to remove it just fail apart. Pick-up new ones hope it is the right fix!