Loss of power in Low RPM?

I ride a 2011 CBR 250R，Recently I have been having a problem with losing power during first and second gears around the low-mid RPM's. It happens when I accelerate at a quicker speed it feels like the power cuts (which engine braking occurs) and then it accelerates again after 1 or 2 seconds.

It usually occurs when I have 1 or 2 bars of fuel left so i believe it might be a problem with the fuel or petrol. I have been filling my tank with the normal petrol required at well known gas stations in my area.

I have recently had this problem but after servicing the motorcycle (a few weeks ago), it was a problem with the air filter being very clogged and dirty, after servicing it was fine, and then this started happening recently.

anyone have any idea what the problem is? I did email honda and they said my chains and sprockets may be the cause to it and they need to be replaced, I'm looking to replace them but I'm afraid if after replacing them, the same problem will still occur.

Engine braking?

Sounds like a bog. Usually a carb issue.fuel injection (fuel) or rarely possible ignition issue.

Air filter? Did you drive through a saw mill/offroad?

Replace the plug and fuel filter. If the bike has a carb, clean or replace the jets. Check and recheck the float setting. Check for a vacuum leak.

If your chain and sprockets need replacing then they need replacing - regardless of whether it fixes the problem - they are consumables, they wear out regularly (this rate can be improved by regular lubing).

Since it occurs at a point when the fuel in the tank is low then my first thought would be that something is clogging the petcock.

If it is fuel injected I would look at the micro filters.

If not I would look at flushing the tank.

Since the air is ok it's gotta be fuel or spark. Check your fuel pressure, fuel filter, injector, finger strainers in the tank, petcocks, and all like that, dude. Gotta glass jar? See, if you pull the fuel line off the petcock or pull the other end off and put the jar in the way gas should, like, run into the jar. It's like, fluid dynamics and gravity, dude. Like, the same basic principle as rain. Every notice how rain falls down? Pretty amazing, right? You don't have to buy a special glass jar, purchase gravity or buy anything, dude. When's the last time you gapped your spark plug? Oops… New concept. Sorry. Look up "gap."

What chains and sprockets are they talking about? Your engine is surging. Maybe they suspect bad valve timing. It's pretty hard to slip the cam chain on that, but if the tensioner gets damaged, it may. If they're telling you your drive chain is the cause of engine surging, they need to go back to school and you need to ask a different shop.

That's what they do. Bike engines only kick in the power at higher revs.

If it runs bad at low gas, dirt in tank is partially clogging petcock and/or line. This dirt clogs idle and slow (pilot) jets, but not mains as much. So, it affects starting, idle. Lower speeds. (if carbureted)

EDIT: I doubt it's bad gas or it wouldn't 't accelerate well under load in 1st and 2nd. And be hard-starting. A Cheap fix though, get Top Tier Ethanol-free Premium or get Regular and that ethanol enzyme stuff. Drain old stuff for lawnmower. Check it actually Flows when draining--not a:"dribble", especially when below 1 gallon.

Try running with filer cap open. May have poor venting.

Drain tank, remove./clean petcock.

Get a big paper inline filter for fuel line. Keep lines as short as possible to maintain siphon. Or, replace filter if EFI.

If this doesn't do it, spray around intake boots and any ports w/WD 40 while idling. A change in engine speed means vacc leak. If you have carbs, spray between then, the plastic connecting tubes crack.

I doubt it's spark. Or it would be hard starting/no start or you couldn't rev out in any gear. I had water once in my igniter, It wouldn't go over 2,000. But, they Can get intermittent and go thermal. Does it do this cold, or Hot? Look at yours closely, look for leaks, see if heat sink compound good and screws tight. To heat sink. Remove plug, tighten connections, plug back in.

By all means, replace chain/sprockets. But this isn't your engine problem. Slipping chains could cause loss of acceleration on hard throttle or in too hi a gear, and over revving, not loss of top end.

I have a gravity-feed, my tank was coated But coating giving way. It would act the same way when less than 1 gallon. I had to put in a small electric pump.

Basic maintenance, check gasoline-- locally problems have resulted from using the ethanol blends, even in the newer certified models. 91 octane unleaded, no ethanol available at some stations- Kwik Trip, Citgo- and that is choice for many people. SeaFoam is other basic additive to gasoline, extra fuel filters helpful at times. Ignition problem? Not likely or you would have more high speed problems as well- BUT a few times ignition advance units have 'stuck and low rpm power loss occurs until higher rpm when advance unit weights or electronic advance goes to full advance or part advance. A few Harleys in first couple years of electronic ignition had this problem, some Kawasakis and Yamaha had occasional fail to advance from 'start' advance, a few instances of full advance at low rpm from CDI/electronic ignitions that had retarded 'start' go to full advance a couple seconds after regular ignition working. First check would be for poor gasoline and fouled fuel lines, filters, then spark plug reading, third would be ignition advance reading with timing light. Cam chain slipped a tooth would be poor run at high and low speeds- used to happen in early 450/500 twins, some on 350s with worn tensioners of earlier design- those were the pre 2000 models. Ignition coils with minor problems usually show symptoms when hot, not cold- or don't spark at all. Spark plug caps and wires sometimes have cracks, gaps, annoying misfires- I had one cap on Goldwing that was moisture sensitive- replaced it and another with 'Marine' terminal caps and no more low speed sputters in rain or damp., .