Help FZR250 - Think I've dropped a cylinder

Not too sure how well it comes across on camera, but the throttle response went out the window, and it sounds like it's dropped a cylinder. Sounds similar to a ninja 300 when I venture past 6,000 rpm

 

I'm going let it warm up then spray water on the headers to see which ones aren't firing. So far I've been told to change the spark plugs, so I'm going to replace all 4 plugs too

 

Has it been sitting for long?

 

Not really, maybe a week at the most, I was talking it easy yesterday because of the wind, although I had to slow down for a sharp corner, and I pushed 2nd gear to about 16k coming off a bridge coming out of said corner, then shifted back up to 5th

 

Looks like I've lost cylinder 4

 

So I'm only running 186.75cc i3 instead of 249cc i4. No wonder I'm significantly down on power

 

I've replaced the spark plug in cylinder 4 to start with, and that fixed the issue for a short amount of time. I've run out of day light, so I'll try to put the rest in tomorrow

 

Suspect your are fouling up your plugs for some reason. If the mixture is way out, it will foul new plugs in absolutely no time.
No amount of cleaning seems to be able to bring them back.
Measure the resitance of the plug with a multimeter (between centre electrode connection and the body). Any value less than about 50M ohm and the plug is cactus.

 

I went for a quick test ride up town to check the mail (about 1.5km) after I replaced the spark plug for cylinder 4. Cylinder 4 was firing on and off on the way to the post office, but worked fine on the way back home until I started to slow down to enter my driveway, then I could hear that cylinder 4 had stopped firing again after I'd entered the driveway

 

Check the plug hasn't been fouled.

 

I tried taking a couple mm off the end of the spark plug leads, let the bike warm up, then went to ride the bike. Problem is still there. My bike idles ok after I changed the plugs and cut a couple mm off the spark plug leads, but when I go to take off, #4 drops in and out still. I can't do much else without removing the engine from my bike, something I really don't want to do. I'm taking it to the mechanic on Monday. My bike has compression and spark, but I don't have the tools or the time to get the AFR sorted.

 

I'd be doing a leakdown test on #4 to see if there is any leakage, and how much if so.

If the other cyls are all OK, spark/fuel is all ok then I would consider valve clearances the next step.

 

Taking my bike to the mechanic to get fixed next week

 

They didn't give me a price, but they are going to let me pay off $100 or so a week. I told them my bike needs the carby balanced and tuned, new plugs, and the ignition barrel needs to be secured.

My last bike (2008 Hyosung GT250R) had mud blocking the main jets in the carbs. They flushed out the fuel tank, cleaned, balanced and tuned the carbs for $360 ish and I had no problems after that.