Big bang on start up

[rha]

I bought my ninja 250 last week and have been riding it a few times no issues. Last time, I started the bike and there was a loud "bang" noise but the bike was fine when I took it for a spin, and no issues when I tested the throttle before getting on. Any ideas what that big bang noise was, and if I should be looking into anything? I'm new at riding so I'm not too familiar with the tech and repairs yet.

[frekeyguy]

Backfire ? It should be fine

[kneedragger88]

mechanical noise or exhaust noise?

[eastcoast_gsx]

Internal Combustion?

[victorbrca]

Had the same happen to mine last week. Looks like its normal when its too cold and the bike has been sitting for a couple of days.

[killerkeith]

Happens a lot with a aftermarket exhausts. One time I fired up my old 250 in while still inside the shed before leaving for work and she backfired. It sounded like the engine exploded scaring the living hell out of me and rendered me deaf for about 5 seconds.

[LannyNguyen]

Probably something with a carb?

[silent_vik]

twisting the throttle when its not running will cause that. i dont think its a big deal but i have been proven wrong many times..

[LannyNguyen]

twisting the throttle when its not running will cause that. i dont think its a big deal but i have been proven wrong many times..

Yeah flooding the carb, when people think they're cool sitting on your bike and start twirking that throttle like they're really riding.

[rha]

Yeah the bike's been sitting cold for awhile so perhaps that was it. At least I hope that's all there is to it. Thanks for the thoughts all.

[TwistedKestrel]

Yeah flooding the carb, when people think they're cool sitting on your bike and start twirking that throttle like they're really riding.

You cannot flood a constant velocity carburetor this way. Twisting the throttle just opens and closes a butterfly valve.

[Bweixz]

Yeah flooding the carb, when people think they're cool sitting on your bike and start twirking that throttle like they're really riding.

oh crap i do that all the time . . .

[taximan62]

You cannot flood a constant velocity carburetor this way. Twisting the throttle just opens and closes a butterfly valve.

Yes but there is an accellerator pump that when the throttle is twisted it squirts a small shot of raw fuel into the intake so twisting the throttle once or twice before starting it you have now squirted raw fuel into the intake. This will likely set you up for a possible backfire.

http://www.youtube.com/watch?v=ZbzBb...feature=fvwrel

[toysareforboys]

Yes but there is an accellerator pump that when the throttle is twisted it squirts a small shot of raw fuel into the intake so twisting the throttle once or twice before starting it you have now squirted raw fuel into the intake. This will likely set you up for a possible backfire.

http://www.youtube.com/watch?v=ZbzBb...feature=fvwrel

LOL @ "Slow motion". Maybe if you didn't record the video on a 7fps cell phone you could do "slow mo" LOL!

-Jamie M.

[TwistedKestrel]

Yes but there is an accellerator pump that when the throttle is twisted it squirts a small shot of raw fuel into the intake so twisting the throttle once or twice before starting it you have now squirted raw fuel into the intake. This will likely set you up for a possible backfire.

http://www.youtube.com/watch?v=ZbzBb...feature=fvwrel

Those are flat slide carbs, not CV carbs. 99.99% of people do not have flat slide carbs in their bike, and if they do, then they know all about how they work.

[taximan62]

Some CV carbs have accelerator pumps. I am not fammiliar with the Ninja 250 whether or not it has one or not?