[psdejong]

Hopefully someone can help me with the problem I am experiencing with my 2005 ZZR 1200. The bike has 2,200 miles on it. I bought it 4 months ago with 1,040 miles . The bike looks like it is brandnew. It runs great. But about a month ago it started hesitating at 2000 - 2500 RPM. Like one or 2 cylinders aren't doing their job. It sputters. It pulls through easily. The more throttle I give the quicker it goes past the critical area. And the bike has plenty power anywhere over 3,000 RPM. Gets up to 170 MPH in no time. When the engine idles, it is not as stable, as it should be, but it never stalls. Running the RPM's up from idle, with no load on it, is OK. It speeds up immediately without hesitation.

It felt to me like the slow jets could be dirty. The previous owner had it sit still for about 8 months.
I put GUMOUT in the tank a few times. Did not help.
I cleaned out the carbs, twice now.
I did find just a little dirt, the first time, but nothing bad. I blew out all jets and air passages. Cleaned and adjusted the sparkplugs while I was at it.

All my labor resulted in no improvement.

Is this something electrical? Like maybe a problem in the throttle position sensor? Ignition timing?

Hopefully someone has an answer before I take it to the shop.
I love this bike and it needs to run the way it should.

Peter, Houston TX
2005 ZZR1200

 

[JimmyD]

Did you try bathing the carb bodies? It worked for mine but the bike was un-ridable, wouldn't idle worth crap and RPMs would hang, etc.

I had cleaned them about 20 times with no luck, used pipecleaners, compressed air, carb cleaner, you name it. Bathing them in seafoam ultimately cured it.

 

[psdejong]

Thanks, I'll see if I get any more suggestions, but I will sure keep this in mind. I have the suspicion that it may be something electrical, though, since the engine runs smooth and has lots of power anywhere above the 2500 RPM range.

 

[psdejong]

Jimmy,
I finally found what was wrong. 1 of the sparkplugs was faulty. It did work at higher speeds and seemed OK if you just tested it, but I found that 1 exhaust piped stayed cold if I would just let the engine idle. New spark plugs and the bike runs perfect.

 

[JimmyD]

I've had a problem like this, but just on older bikes. The connectors in the plug boot sometimes come loose with engine vibration, although this is more common on a twin.

Glad to hear it worked out for you!