I recently bouhgt a 2006 500r ninja for my son. It only had 515 miles on it and was like brand new. We put in new gas, plugs, changed oil, and sprayed some cleaner in carbs. Ran real good. After putting on about 300 miles it is now sputtering and stalling when attempting to start. It does it when starting in morning with choke and even after riding and restarting. Once you get it started it idles fine and runs good. It is only on the start up that this happens.
Any ideas?

 

hmm, mine sputters if sitting for only a few days of no riding and generally it is because the gas gets bad and this ride is really sensitive to that.

 

I assume you have tanked up after 300 miles, what kind of gas did you use? My ride won't talk to me for a week if I feed her the cheap stuff. Also if it had been sitting for a while it might have had some gunk built up that's broken loose and is clogging it up, if you can't find any other problems I'd do a deep clean on the carbs. Let us know what you find

 

Cold engine mojo. What plugs are you running?

 

We have refueled and run premium unleaded. I run non-ethonal in my bike. We put in NGK plugs immediately after we purchased it. The last tank we ran seafoam in it and it doesn't sputter every time now. We may have to do a deep clean with the carbs. My son also said it starts better standing up straight versus leaning on the kickstand.

 

My son went on a 60 mile ride this morning (all highway) and about 6 miles out of town the bike started sputtering and would die when he stopped. After letting it set for a while it would start and run then sputter somemore.
Does this sound like carb problems?

 

Probably don't need to run hi-test unless it specifically calls for it; I doubt that it does. Stay away from the E-85. Also, since the bike starts better at vertical, you might have an issue with your floats sticking/rubbing or the fuel not "reaching" the happy parts. It's possible the primaries may have a bit of crud in them; doesn't take much to ruin your day. Back to the shop to pull the carbs.......

 

I rode the bike last night and it ran great. My son did give is better details of what the bike did on his ride. He said that it sputtered bad and backfired a couple times. My buddy who replaced the plugs when we bought it said that one of the plug wires was kind of corroded inside and did not snap on like the other one. We think maybe this plug wire may be causing the problem. We will do and ohm test on the wires tonight.

 

Ran ohm test on plug wires. One side 4.75 and other side 5.25.