07 Nytro problems

[mark g desantis]

Good afternoon. I have a 2007 Nytro(vector), with 9200 miles. This thing has run flawlessly since new. I was up in northern Wisconsin a couple of weeks ago, and for the first two days it ran perfect. Halfway through third day it started with a shudder on acceleration, and then would not run over 60 miles per hour. It seemed to run good up to about 45, then labor a little up to 60. Ran it this way rest of the day ,did not get any worse, but no better. Started to diagnose this week. Thinking mabey clutching, bought ebay primary, cleaned secondary, everything looked okay. I bought the new primary because the original had worn the sheaves concave, and rollers were probably worn anyway. I ran the sled with the track safely jacked clear and it ran okay , right up past 8500 rpm, but don't know if this is a good test. We do not have snow in central Illinois now ,so i cannot trail test. Jackshaft and driveshaft bearings are good, no problem there. I wondered if it had dropped a cylinder. Ran again, shot pipes over track with a heat gun. Two outer pipes 180-190 degrees, center 145. This does not seem right? Pulled plugs and center plug was black on electrode, two outers were lighter. Tested coils, swapped coils, swapped plugs, same result. Center cylinder is on right, Outer cylinder on left. Starts fine , idles fine, throttle response seems fine on stand. Sorry for the long story, but does anyone have a suggestion before I drive seven hours north again? Thanks in advance for help.

 

[Fast Lane]

Clean the middle carb. It must be running rich for a reason.

 

[Fast Lane]

These have 8000 kms on them. I pulled them yesterday.

 

[mark g desantis]

These have 8000 kms on them. I pulled them yesterday. View attachment 171398

Got it, center carb main jet plugged by piece of fibery junk. I had installed new in tank filters last spring. Mabey should have blown out before installed. Anyway, runs crisp now. Thank you for your help.

 

[Fast Lane]

I found out the hard way that knock off fuel filters fall apart. Always buy Yamaha filters.