I assume that the engine is warmed up. The first thing I would look is the fuel distributor. If you can get ahold of some of the old cis gauges you can test system pressure with the pump running. Does the pressure stay up when you open the throttle or does it dive? A rare problem would be a clogged fuel filter. That is a longshot though. The fuel distributors are tempermental. You can pull one injector and manipulate the air plate to see if you are getting an increase in volume. Check to see that the plate moves freely. You have to remove the big boot to do this. Don't pull it any direction other than up.

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64 European Coupe Brilliant Silver with Red interior 4 Speed Sunroof
87 TDT 286k
87 SDL 195k
83 SD 202k
83 SD 201k
83 D 286k
02 R1150RT 32K
00 122HP FLSTF
07 KTM 250SX

"Danger takes many forms"