Just need some general carby help with a CBR250RR MC22 that won't start but didn't think this would go under the CBR section.

Won't spark, starter runs but the engine doesn't catch. I bought a can of Nulon carby cleaner and hosed the butterfly valves down and let it soak good. Still won't start. I tried with the fuel system on RES and ON, both no go. Could something be blocking the fuel flow?

Rrotz wrote:Just need some general carby help with a CBR250RR MC22 that won't start but didn't think this would go under the CBR section.

Won't spark, starter runs but the engine doesn't catch. I bought a can of Nulon carby cleaner and hosed the butterfly valves down and let it soak good. Still won't start. I tried with the fuel system on RES and ON, both no go. Could something be blocking the fuel flow?

Check electrics first before taken a wrong diagnose

Do these plugs look knackered? I just replaced them about 2 years ago. They were all a bit mucky so I cleaned them up and I got some combustion sounds when I tried it next.







This is what I get when I try to start it.

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I'm going to pull the carbs out this weekend but I sprayed a bunch of carb cleaner down it and even "start ye bastard" spray won't get it going. Any diagnosis before I go in the wrong direction and clean up the carbies?

I'd get some new plugs or if you've got an ultrasonic cleaner
Stick them in there for half an hour.
Are the carb fuel chambers filling? Could be stick float valves??

From the look of the plugs is the bike running rich?

The airfilter still looks good but the oil is dark, I may need to do an oil change at the same time.

Have you had your valve clearances checked recently? My racer is hard to start when the inlet valves are under the required clearance.

dunkenb wrote:I'd get some new plugs or if you've got an ultrasonic cleaner
Stick them in there for half an hour.
Are the carb fuel chambers filling? Could be stick float valves??

Don't know how I'd go about checking that yet, I'm still a novice at basic engine mechanics.

I got 4 spare plugs today to replace the old ones...took out #2 and it looks like this. Broken porcelain! Am I fucked? Is it down in the engine now?

Think I can hoover it out?