occasional uneven acceleration

[jimmyfz6]

Sometimes when I roll on the throttle smoothly, my bike seems to accelerate unevenly. It will go then kind of cut out, then go again. It seems most pronounced in 1st and 2nd gear. It only happens once in a while and the engine temperature doesn't seem to matter. Sometimes it happens even after I've been riding for little while. I've just been rolling on more to accelerate through it, but it doesn't make for a smooth ride. Any advice on what it could be?

 

[FZ09Bandit]

I remember experiences a sort of hesitation on mine, but I think you may need to do a throttle body sync. That would put you on a good track.


Sent from my windows phone at 430 AM on the cot after a transfer to a crazy house

 

[FinalImpact]

Do search for TPS in the Tech section (sticky IIRC) and read that.

Otherwise start with the basics;
TPS, Fuel Quality, Fuel Delivery, Battery Voltage/cables ect.

Inspection of (ACTUALLY TAKE STUFF APART):
Electrical connectors at the TPS, Battery, ECM, coils....

 

[aclayonb]

Mine does this when I'm dangling on the edge of a closed throttle and moving slowly for that gear (sub 4k RPM). This started when I finally got used to the snatchy throttle. You've probably just developed the smooth touch needed for this bike and are at the make/break point on the throttle.

Then again, it might not be your issue. If you have a manual - TSA. No, don't put fingers in strange places... (take stuff apart). The worst thing that can happen is that you forget how to put it back together and I buy it from you at a deeeeep discount.

 

[TownsendsFJR1300]

Sometimes when I roll on the throttle smoothly, my bike seems to accelerate unevenly. It will go then kind of cut out, then go again. It seems most pronounced in 1st and 2nd gear. It only happens once in a while and the engine temperature doesn't seem to matter. Sometimes it happens even after I've been riding for little while. I've just been rolling on more to accelerate through it, but it doesn't make for a smooth ride. Any advice on what it could be?

Do you use the RED KILL SWITCH OFTEN?

Its a known weak point and with possible dirty connections inside, can cause your issue.

If its really bad, you can duplicate the issue while parked, engine running, and lean on the switch a little bit and see if the ignition cuts out..

http://www.600riders.com/forum/fz6-electrical/48311-run-switch-faulty.html?highlight=kill+switch+fix

 

[norcalwelder]

I had some stumbling around idle to 3K RPM on mine last summer, new spark plugs helped. I ultimately found replacing my coils with a set off ebay for $30 did the trick. If you want to see if one of your cylinders is cold (dirty injector, plugs, etc) you can let it idle for about 5 minutes and then shut it off. Take a cheap plastic pen and run it down a little section of each header close to the head. It will leave a streak of plastic. Do this on each header a couple times and suddenly you will find the pen doesn't melt on one of the header pipes, showing you the problem cylinder. Learned this trick when I was working on airplanes, works like a charm!

 

[ChanceCoats123]

I had some stumbling around idle to 3K RPM on mine last summer, new spark plugs helped. I ultimately found replacing my coils with a set off ebay for $30 did the trick. If you want to see if one of your cylinders is cold (dirty injector, plugs, etc) you can let it idle for about 5 minutes and then shut it off. Take a cheap plastic pen and run it down a little section of each header close to the head. It will leave a streak of plastic. Do this on each header a couple times and suddenly you will find the pen doesn't melt on one of the header pipes, showing you the problem cylinder. Learned this trick when I was working on airplanes, works like a charm!

This is a good idea. If you're not a fan of sticking your hand down there, then you can easily substitute a spray bottle of water for the pen. After the engine is warmed up, the headers should easily be hot enough to vaporize small water droplets. Spray each header pipe and if any of the pipes stay wet, then odds are that you have an ignition or fuel delivery problem with that cylinder.

 

[FinalImpact]

This is a good idea. If you're not a fan of sticking your hand down there, then you can easily substitute a spray bottle of water for the pen. After the engine is warmed up, the headers should easily be hot enough to vaporize small water droplets. Spray each header pipe and if any of the pipes stay wet, then odds are that you have an ignition or fuel delivery problem with that cylinder.

+1 ^^ simple and effective temperature test!

You can take it step further and spray plug wires and coils too. Should they be acting up (i.e. = leaking energy), it will begin to misfire.

Knowing you can induce a misfire with a little moisture, well - you can bet what will happen if ridden in the rain on Friday in heavy traffic! If all is well, the ignition system can handle moisture.

If the plugs gap is too great or the plug is defective in someway, this can induce leakage that otherwise wouldn't occur. That said, the coil and wires dielectric withstand voltage should handle a bad plug and not jump through theirs bodies.
A key point in the OPs post is that "does it under load". Although trying to accelerate in 4th, 5th, & 6th gears places a greater load on the ignition system so if this were ignition related and from say 5th gear @ 35 mph went to WOT and it starts bucking, I'd be looking at the ignition.