2010 Ninja 650 Stuttering Problem?

[Senshi]

Hi,

I rode my friends 2010 Ninja 650 yesterday as he said it had a problem. In all gears it is stuttering at all different RPM levels so I am actually shaking forwards and backwards on the bike despite holding the throttle constant. Any ideas what this can be? He has 24000 km on and rides in all sorts of weather. The symptom is almost like I just keep twitching the throttle on and off really fast to create the stuttering feeling. Hope I am descriptive enough. Any idea are appreciated.

Thanks!

[jay-d]

Could be many of things! First, I would start with gas.

I know my previous bike was kind of picky with what gas I put in to it. Did he just take it out of storage? If so, maybe he didn't put fuel stabilizer in?

Did this just happen out of the blue? If so, what was the last kind of maintenance he did? Did he perhaps forget to plug in the MAF sensor?

This is all speculation until you give us some more info because really, it could be something really stupid that he overlooked.

[Senshi]

Could be many of things! First, I would start with gas.

I know my previous bike was kind of picky with what gas I put in to it. Did he just take it out of storage? If so, maybe he didn't put fuel stabilizer in?

Did this just happen out of the blue? If so, what was the last kind of maintenance he did? Did he perhaps forget to plug in the MAF sensor?

This is all speculation until you give us some more info because really, it could be something really stupid that he overlooked.

Last season we did spark plugs and air filter at around 20000 km. It was running fine, he didn't store the bike and rode it all winter. I asked him about fuel and he never let the bike sit for more than 2 weeks without riding it. This season he has put a couple thousand km on already and he hasn't done any service that I am aware of this season except new tires. He did go one size wider on his rear tire for some reason, but i assume the bike was running ok with the new tires for a few thousand km so far till now.

What is the MAF sensor?

[jay-d]

Last season we did spark plugs and air filter at around 20000 km. It was running fine, he didn't store the bike and rode it all winter. I asked him about fuel and he never let the bike sit for more than 2 weeks without riding it. This season he has put a couple thousand km on already and he hasn't done any service that I am aware of this season except new tires. He did go one size wider on his rear tire for some reason, but i assume the bike was running ok with the new tires for a few thousand km so far till now.

What is the MAF sensor?

The MAF (mass air flow sensor) reads how much air is coming in so the computer knows how much fuel to put in. If that is unplugged, your bike will go in to a "limp" mode, which is basically what you're describing because the computer is missing key information from that sensor. It's really tiny, usually mounted on the air box somewhere after the air filter.

It doesn't make sense for a bike to behave the way that is without some sort of intervention. Maybe the sensor was never "clicked" in to place and it just happened to fall out? I would check all vacuum lines and hoses, something must have come loose with the vibration because you did do maintenance not too long ago.

Start with the simplest solution first and work your way to the more expensive stuff. So, first thing, double and triple check all connectors and hoses.

[Senshi]

The MAF (mass air flow sensor) reads how much air is coming in so the computer knows how much fuel to put in. If that is unplugged, your bike will go in to a "limp" mode, which is basically what you're describing because the computer is missing key information from that sensor. It's really tiny, usually mounted on the air box somewhere after the air filter.

It doesn't make sense for a bike to behave the way that is without some sort of intervention. Maybe the sensor was never "clicked" in to place and it just happened to fall out? I would check all vacuum lines and hoses, something must have come loose with the vibration because you did do maintenance not too long ago.

Start with the simplest solution first and work your way to the more expensive stuff. So, first thing, double and triple check all connectors and hoses.

Cool, i'll try that, I have the service manual so I can find all that stuff you mentioned.