2018 300rr carb insanity

[Trail Rider]

background - Was riding the other day, bike running fine. I had a minor tip over in the snow, float bowl stuck which I fixed by tipping opposite way. then the bike would not start. Since then I have had the carb off 2 times & everything looks great. Jets clear, bowl adjusted. I open the fuel valve & the bike starts instantly & sounds good, but when I give it any throttle, baaawaaa & it dies. The fuel is not overflowing so the bowl must be doing its job, the bike is jetted correctly. But when I check the plug it is wet, I also noticed what seemed like fuel in the air box. I cannot figure this one out, any ideas?

One other thing is I changed the intake reeds but had 4-5 rides with no problems. Maybe a chance something came loose?

[Trail Rider]

My one other lingering thought is whether this could be an ignition/spark/electrical issue. I checked resistance at the coil & it mostly seemed good. The resistance between the coil & the end of the spark plug wire was around 6, the spec said 13.2. My readings could be off a bit, and if the spark was very weak I wouldn't think it would start right up & run nicely on the initial start.

[Hurky]

I would recheck your intake reeds again, fuel in the air box could be that the reeds don't fully close and the carb is 'back feeding' the airbox with mixture, just a maybe ...

Cheers

[JoeMaico]

Will it stay idling for a long period of time when you start it - without touching the throttle? If so, it sounds like a fuel starvation issue. I would check the petcock and make sure it is flowing without interruption. Then I would concentrate on the float and the float needle again - especially the float needle. If it is hanging up, it will never run long past idle.

joe

[Trail Rider]

I cant seem to run this thing down. I've had the carb off numerous times, everything looks great. As one aside, after the issues started I put in a new plug to make sure that wasnt the problem, subsequently the bike wouldnt even start anymore. A few days later I put the old plug back in & it starts, turned out the new plug was bad, hard to believe. it would not produce a spark.

Anyway, current state is that it will start & idle perfectly. It will rev high without a fast twist of the throttle. Medium to high twists cause it to bog & die. I know that sounds like a lean carb issue, but the carb appears fine, jets are clear, its clean, I've adjusted the float. The jetting is the same I've always used. I even put on a new coil when the new plug wasnt sparking, I checked resistance on the stator connections, all good.

I have no idea what else to do.

[JoeMaico]

That is odd. Especially when you indicate that it all started after a crash in the snow, resulting in a stuck float. Floats don’t usually stick after a crash, unless something gets bent inside to affect the movement of the float. I still think the issue is somewhere within the fueling circuit. I assume the float has no holes in it. You would notice the extra weight when you had it off - probably. If you have a buddy with a 26mm Keihin, see if you can borrow it to run a test. Put your needle and jets in, and see if it solves the problem. If it does, then there is some mechanical damage somewhere within yours.
joe

[Trail Rider]

That is odd. Especially when you indicate that it all started after a crash in the snow, resulting in a stuck float. Floats don’t usually stick after a crash, unless something gets bent inside to affect the movement of the float. I still think the issue is somewhere within the fueling circuit. I assume the float has no holes in it. You would notice the extra weight when you had it off - probably. If you have a buddy with a 26mm Keihin, see if you can borrow it to run a test. Put your needle and jets in, and see if it solves the problem. If it does, then there is some mechanical damage somewhere within yours.
joe

Joe, good ideas, thx.

[Trail Rider]

Tried a carb from another bike, same result. Starts fine, begins warming, then un-rideable bog. ugg.

[JoeMaico]

That is a shame. Because it sure sounded like a fueling issue. Now you have to work your way through all of the possible electrical gremlins. You indicated it all started with the crash in the snow (or tip over). So, time to look for loose or broken connections. Pull the flywheel cover off and see if you have a ton of water in there from the snow. I hate chasing electrical issues. But you have to start somewhere. Good Luck.
joe