ninjette.org - View Single Post - Reviving a Ninja 250 - Low compression

spotmaxdog · January 28th, 2022, 10:45 PM

Update:

It was the piston rings. Took the engine down to the jugs and the rings were solidly stuck in their grooves. Freed them and am now showing 150psi for compression.

Now I'm troubleshooting the fuel. I can only get it to run on starter fluid in the airbox. Carb seems to not be contributing any fuel/air mixture to the engine. I've cleaned it 4x, blown out passages, replaced worn out jets with new ones... nothing is working

Typical start attempt is a second of starter fluid in the airbox and then I'll crank with throttle half open. Bike starts, jumps to 5000RPM for about 2 seconds and then dies. Pretty sure it's just burning the fluid mix in the box and then dying due to lack of fuel.

I've tried air mixture screw settings of 0.5/1/1.5/2/2.5 but none of them seem to have any effect on the engine.

Not sure what to check next. Airbox is hooked up with the crankcase breather tube. I've worked on bikes before that have marginal carbs, which makes them run crappy or stall with throttle but to have absolutely zero workable air/fuel is a new one for me.

January 28th, 2022, 10:45 PM	#4
spotmaxdog ninjette.org member Name: Terry Location: Pensacola FL Join Date: Jan 2022 Motorcycle(s): BMW R1200GS, R1100S, Suzuki GR650, Ninja 250 Pregen Posts: 24	Update: It was the piston rings. Took the engine down to the jugs and the rings were solidly stuck in their grooves. Freed them and am now showing 150psi for compression. Now I'm troubleshooting the fuel. I can only get it to run on starter fluid in the airbox. Carb seems to not be contributing any fuel/air mixture to the engine. I've cleaned it 4x, blown out passages, replaced worn out jets with new ones... nothing is working Typical start attempt is a second of starter fluid in the airbox and then I'll crank with throttle half open. Bike starts, jumps to 5000RPM for about 2 seconds and then dies. Pretty sure it's just burning the fluid mix in the box and then dying due to lack of fuel. I've tried air mixture screw settings of 0.5/1/1.5/2/2.5 but none of them seem to have any effect on the engine. Not sure what to check next. Airbox is hooked up with the crankcase breather tube. I've worked on bikes before that have marginal carbs, which makes them run crappy or stall with throttle but to have absolutely zero workable air/fuel is a new one for me.