CBR 125 - Hard engine brake / bad throttle response

[JaniHun123]

Hey everyone.
First of all sorry for my bad English.

I have bought a CBR 125 (2007 model) a few months ago and noticed the engine braking is too hard. I cant even shift down to first gear without stopping the bike because it would lock my wheel.. Also i feel a very bad throttle response, if i am going slow, its changing my revs a lot. Its like yanking. So its not smooth on slow.. (I am keeping the throttle on one place for sure..)
Also the bike cant really go on idle (So if i switch to first gear and i slowly release the clutch and no throttle) the rev drops so much and the bike is yanking.
Today after a corner it dropped my chain, i think its not too loose because i was putting it back like i was put the chain on the top on the sprocket and then move the bike backwards. and it was going on well.
And sometimes it drops out the gear, it gives a false neutral and then after like 1-2 seconds it goes back in...

But the main problem is the engine braking and the bad throttle response..
My idle rpm on cold is about 1.5k and when its hot its about 2k.
Anyone got ideas?

Thanks in advance

[barrkel]

If your chain came off the sprocket it's way too slack (in fact it's probably worn out). If there's uneven stretching then it'll mean you don't get constant speed from constant throttle input; and a slack chain means poor gear shifting. And it could be rubbing / binding against something when the slack is in the other direction (engine braking).

I wouldn't expect a 125 to do much more than lug if you let the clutch out with no throttle.

If you can pull the chain off the back of the sprocket enough to stick a matchstick in there, it's done. Chain and sprockets need replacing.
____________________
Bikes: S1000R, SH350; Exes: Vity 125, PS125, YBR125, ER6f, VFR800, Brutale 920, CB600F, SH300x4
Best road ever ridden: www.youtube.com/watch?v=s2MhNxUEYtQ

[JaniHun123]

Thank you for your reply.
I forgot to say when i ride the bike and i do not use the throttle, the bike is meowing, like a cat. it gives a weird sound. I think the chain gives that sound. It may be normal but i havent heard it on other bikes soo i dont know, its like a supercharger sound like lol. Or something like that.

I will check the chain and the sprockets and see tomorrow.
If its worn then which sprocket/chain kit do you suggest to use?

Thanks

Edit: I mean the chain is whining. or it gives a weird sound. If i use the throttle i cant hear it because of the exhaust but if i release it i can hear it whining.

Edit2: I was going to check the bike now.. And i think that chain is loose waaay too much and its also rusty. And my wheels are not aligned(im not sure).

[Teflon-Mike]

We have to presume you are a Learner rider on CBT and not a qualified experienced one. This starts us at a base where the most likely case of such 'problems' is not necessarily the bike, but your degree of learning.... and or a combination of both!

Next up chains should not fall off!!!!!!!

It's a 2007 model, so a ten year old bike, that has plastic "I wanna-be-a-race-bike' play-suit on it... this atacts owners more interested in GP hero fantasies and ragging the crap out the thing trying to go fast and spending any time and money and incompetence they may have with spanners, NOT doing good basic maintenance but ill conceived 'mods' to make to go fast or sound fast or look fast.... and yours has had a decade of such owners, and is likely at about, if not past, if not well past! its anticipated service life.....

Your previous post was about poor starting, hoses, possible sludge in the tank and an air-filter....

Before gong ANY further, this sort of suggests you have an old, sore used 'sporty' 125 that has not had an easy life, in a world where learner bikes tend to live hard ones anyway, and you probably aught have an L-Plate on your tool box as much as you do your bike....

Now, if you want to learn mechanics a bike riddled with niggles is a great thing to tackle.... but if you want to learn to ride, it tends to be rather frustrating, and if you are trying to learn to ride AND to learn to do mechanics you are on a high road to the asylum, never knowing whether a fault really is a fault with the bike or something dumb you are doing with it....

Hint is here, that this bike is likely not the one for the job you are trying to do before you start, and like the Irishman asked for directions, I wuddna-be startin frum 'ere, now!... you MAY want to consider chopping it in for something a tad less old and or sporty and a little more 'boring' and basic... bikes without plastic frocks are a heck of a lot easier to work on, ones without water cooling, and radiators and a platora of additional hoses even more so; there's a chunk load less to go wrong with them, and if it does, its a darn site easier to get at, get to grips with and sort out....

And starting where you are with a bike so poorly maintained it chucks it's drive chain.... the £50 it will cost for a new Chain and sprocket kit it undoubtedly needs is likely the thin ends of what is likely to become a very thick wedge as you chase the problems and the amount of 'maintenance overdraft' this bike is likely to be in......

Which is all doom and gloom, B-U-T... take heed... I would lay odds that on top of the Chain & Sprockets the cush drive rubbers, if they haven't started to crumble are shrunk, hard and nie on useless... they are aother £15 on top of the C&S kit... and then you undoubtedly have to contend with missing sprocket circlips and chewed sprokcket bolts, bent axle adjusters and chewed adjuster bolts.... JUST to make a good job of a new C&S kit so that it actally does the job it should and doesn't end up like what you have in a matter of months, you are looking at the better part of £100... and that's before you pull the wheel and see the state of the brake pads, the brake caliper and the wheel bearings...... and so it goes on.....

And the ramp of the wedge starts to get very thick very quickly, and you find you are either doing a full ground up renovation, to bring the thing back into good serviceable and reliable condition, OR you are trying to work out where you can skimp a few quid on things to 'get me by' and adding to the myriad bodges the poor bike has already suffered, and NOT getting 'value' from what you do spend, as you are constantly working round niggles that aren't tackled or are patched over....

Think long and hard about this; what you got, here ad now is likely to be a money pit, and you are on a road to a heap of learner-frustration tryng to learn to ride ad learn to fix, and not knowing whether anything is the bike not dong what it should, or YOU.

If you persevere.... and that should be an IF.... the Chain & Sprockets need replacing as course, the cush drive rubbers along with them, and as mentioned, probably the rear wheel bearings, the chain adjusters and a load of pice parts like circlips and bolts.. and that s just to 'base line' whats going on so that you can rde the thig and start chasing other niggles...

Odds on that the juddering and lurchng and excessive engine braking is as much you as the bike; very very common newby error is to over-shift, changing up too many gears too quickly, making the bike labour in a higher gear than it needs, and havig to crash back down them all too fast making the motor give far more engine braking reaction being reved up by the back wheel each rushed down shift... a tendency that has the habit of stretching chains, hammerng cush drives and killing sprockets, and wheel bearings!!! So all something of conspiracy against little learner bikes really....

And you have a chunk load of work to do and money to spend to get far enough to find out where the problems with the bike stop and the problems with the rider start.....

Next one, as also alluded to will be brakes.... if you are using the brakes properly, as you should have been taught on CBT, your frst brake s the third brake, engie braking... slowng on the throttle NOT crashing down gears making the back wheel skid! If you need that much braking you sould be doing it on he actual brakes.... and on a bke of that type ad that age.... and a Honda... their Nissin calipers really dont like British weather any better than we do! The calipers could probably do with a damn good overhaul, stripped down and properly cleaned, the float pins properly greased and the whole lot fitted back up with ice new pads and fluid.... and that's assuming that the brake pistns go back 'in' and aren't corroded to feck before yo try and cut up the cylinder seals on the way.....

New brake pads are about £20 a pair, new float pins new rattle clips, bleed nipples and rubber boots and gromits a few quid each, but a piston and seal kit is about £20 a caliper, so you are looking at around £50 a brake to properly overhaul them....

And that is the next likely niggle where getting past bash-down braking using the brakes properly you find it hard because they lack bite and or feel or due to them sticking on rusty floats and sticky pistons they squeel, grate and dont work consistantly ever time, makig your job of learning all the harder working around the niggle...

And you likely still lock up... which is not helpful this time of year when the roads are getting wetter and covered with rotting leaves, and tyres come in for attension... and steering bearngs... and a fork overhaul... as each niggle de-nigged shifts the spot-light....

Like I say think long and hard whether this is the 'best' bike for you here and now... how much harder its making your early miles learning, how much hassle its already giving you in mechanical melodrama and how much more its likely to give as you try and tackle it, and ore, how much actually sorting it WILL cost in blood sweat and tears...

As it stands the bikes worth what? £500 ish? You ARE looking at likely having to chuck HUNDREDS at the thing to drag it out of maintenance over draft and make it a half decent reliable every day rider.. AND having all the hassle and blood sweat and pain along the way to do so...

Backing up, taking the Irishman's advice on directions, and starting some-where else, that possibly costs you more upfront, is likely the easier and cheaper option long term; having a bike that just 'works' and doesn't throw bum biting bills at you as you go, or give you more to worry about than you need by way of 'niggles' that could be the bike, but as likely are your riding, as well as the frustration of hang to twiddle spanners and skin knuckles just to find that out!

How much can you afford to buy a bike, that DOESN'T need this level of spanner attention chucking at it just t make t work half way like it should? And how much 'boring' can you suffer to get it?

I have to say, I quite like 'boring'... it's not so exiting when it works... but BOY! does it just 'working' when you want or need it to make up for Sooooooo much! If you are a real masochist you can save the skinned knuckles and spanners for a 'project-bike' that doesn't have to get you anywhere, and is just for 'fun'...

BUT, here and now is, we can definitely say you need a new chain and sprocket kit, you can certainly add to that new cush drive rubbers, and likely a bunch of piece parts like axle adjusters and sprocket circlips... the thin end of that wedge you are looking at is around £100's worth... and THAT is to merely discover that short shifting 'up' the box and 'crashing down' isn't the best way about things, and changing your riding style, learning to ride for response, use the revs not the gears so much, use brakes for braking throttle just for speeding up and slowing down, aiming for 'smooth' is whats really needed...

Sort that, and then its back around the loop the ext niggle... as said, likely brakes ad or tyres, and after that steering ans suspension... and so it goes on.... suffering the hassle, the pain, the evenings in the rain and paying for the privilege as you go... like I said, how much is this bike worth? Think long ad hard about it. IS this bike and the hassle and costs that come with it worth it to you?
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[JaniHun123]

Hey.
Thank you for your answer.
My brakes are fine as they were changed like 100 miles ago.. The discs are great, i just had to change pads. (Edit: a mechanic changed it not me of course..)
(Edit: I dont want to be a mechanic, just want to make the bike comfortable to ride but i cannot afford to build a whole new bike of course, thats why i bought this one for 700 pounds because i dont have any more.. Explained later.)
I am not really shifting gears every 3k, i am using less gears more revs.. My father have got a LOT of experience on bikes and he said the thing too that i was writing here already. It shouldnt have that hard engine brake of course, locking up at 10mph...
I will bring it to a mechanic today and see what he can do with it. I have bought it for cheap because i am not from the UK, i am poor af... I dont have a job yet as i cant (I am 17, will be 18 in December...). So.. But i needed a transport because Agencies said they cannot give me a job without my own transport, i got it and then they said they cant give me any job before i turn 18. So what can i do then? It sucks i know but i cant do anything with it, i had to buy a cheap bike because i have got 0 pounds at all. Zero. From where would i have any money if i cant work. I came to the UK when i was 15 so sitting in my room 2 years ago.... (College's said i cannot go there already because i was too old (?))... so..
I want to make a use-able bike from what i got... I havent had 2k pounds to spend on a bike, havent had even 1k. This is what i got for the money..
Soo you say i should buy chain, sprockets and what else? What else is neccesary to ride the bike? Because i can go with it now too but it feels uncomfortable to ride (i even wanted to do my driving test on a car and buy one...)..
I just have to use the 2nd gear at about 15-20mph because i cant shift down to the first gear because it would lock up the rear wheel. Also if i want to shift down from 3 to 2 at about 5-6k it would use a LOT of engine brake.. so..
The things you write were way too long, i couldnt understand half from that because i am not from the UK as i said but you can see it too for sure.

Soo my question is again, what should i buy to ride the bike comfortable? The most things make it uncomfortable is the hard engine brake and the very bad throttle response..

Thanks.

Edit.: If you check the MOT history of the bike it looks nice btw...
This is my licence plate: HN07DKX
When i bought the bike the speedo didnt even work (So it havent counted miles also).. Dont know for how long but i have replaced the cable already and its fine now but the mileage is not real then.

Edit2.: I am not a racing kid, i am not racing the bike btw. Just using it very less daily right now, like 15 minutes... After i get a job when i turn 18 i want to use it to get to work and home..

Edit3(lol)..: Also if i get a job i think i will buy a car anyway because this is a bad experience on bikes.. And a normal condition 125cc cost 2k+ .. so i should just wait to turn 19 (?) and do a bigger bike test, that is more worth it.
I havent done any modification on this bike btw, the previous owner fitted a Blackwidow exhaust and thats it. (Or i dont know what else changed but that is for sure).

[P.]

Idle is too high, should be 1400-1500 when warm.

1st gear is going to have insane engine braking, should be out of 1st gear before you are at 10mph, You'd never need to use 1st or 2nd once you are out on the road.

Its a single, a small single, so its going to have a nice bit of engine braking. That is how it is.

Chains should be tight enough, but have room, so about an inch of play in the centre of the lower run of the chain.

Where are you based, if you are anywhere near me I'll take a look for you.

[JaniHun123]

Hello.
Thank you for your answer.
I am in Melksham, Wiltshire.
Ehm if i want to use higher gears the bike is struggling for some reason. It feels very weak. I am about 85kg and 170cm.
That would be great if you are near me and can take a look on the bike

Thanks.

Edit: If i set my mixture screw to get my idle that low the bike wants to cut off, thats why it is this high.

[P.]

Mixture and idle are 2 different things.

You want to set it to stock settings and get the bike warm. Then set the idle, once the temp needle is near the middle. Takes a while on the CBR125 though, so go for a ride, probably 15 minutes or so.

Afraid I'm a bit far. Near London.

The CBR does need to be thrashed, you'll want to have it around 11-12,000 rpm before changing up if you are 'getting a move on'

Don't use 6th unless you are really screaming it down a hill. Its more used for a relaxing ride either down hill or on a very long straight on a non-windy day.

[MarJay]

That chain is about as f*cked as I've ever seen one. The adjustment is on the limit and it's still hanging off.

I think you need to take your bike to a mechanic and get it thoroughly looked at. It's probably got more than just that problem.

Engine braking on a 125 shouldn't be as abrupt as you say unless your ham fisted with the clutch... and as I said, I've never seen a chain that bad, which indicates that other things may well be wrong with the bike.

Hopefully a helpful soul near to you can come and have a look and help you out because I can't recall seeing something as bad as that before (with the exception of Bodytard's welded on sprocket, maybe).
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[JaniHun123]

Hey.
Yes London is a bit far.
How do i set it to factory? I would do that and see if its better.

Thanks.

[P.]

Didn't see pics, but yes, that requires new chain and sprockets and the bike needs a quick clean.

[MarJay]

[MarJay]

Chain and sprockets for a CBR125 appear to be very cheap. Wemoto has a heavy duty chain and sprockets for £27.33. A mechanic would probably charge an hours labour to fit it.

A small price to pay to make the bike safe and probably solve many of the problems. I realise you're a skint 17 year old, but sometimes you have to spend money to save money. It'll cost you a lot more if the chain snaps when riding.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Nobby the Bastard]

[Nobby the Bastard]

Right, that chain is appalling. It's possible that it was always too long, so I could take a link out, but if I think it's fucked I'll say so and won't shorten it. If you choose to ignore this, continue to ride it and it snaps and takes a fucking huge chunk out of your leg it's your lookout.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[JaniHun123]

Thank you for your replies everyone.
I have bought a Castrol Power 1 Racing Motorbike Oil today at night (ordered it online), tomorrow will change the engine oil. I was talking with a mechanic (i know him well, also he changed my brakes about a month ago) and he said that the sprockets and chain is 100% replacement. So i have to order a new sprocket and chain kit. He will do it for half price (or even free) for me because i know him well. I will tell him if can he align my back wheel properly. I am minding on changing the air filter too.
I have never ever lubricated the chain. That is my bad i havent had the knowledge. I seen some of you would check the bike happily but i dont really have any money right now. I have no friends here in the UK, soo they couldnt tell me about bike maintenance. I have moved home 3-4 times and i am 17 so i had to start a "new life" a lot of times at my age. Its hard to find friends all the time:) When i was in Hungary (im from Hungary) then i found some always in school but here in the UK i dont have a school and not going anywhere tbh.
Soo back to the bike.. Will buy the sprockets and chain kit in a few days (i hope) and then bring the bike to the mechanic to fit it.

Thanks

[Nobby the Bastard]

[P.]

Replace oil often with cheap 10w40. Every 3000 miles. You'll be better off doing that.

Let Nobby have a nose over it. Chain and sprockets are needed and would be better than expensive oils.

[JaniHun123]

I have got some left on my Amazon Balance. Thats where i bought it from. It was 10 pounds.
But i cannot buy sprockets and chain from Amazon because they dont have any..
I know you havent asked for any money but i just said i do not have any if someone checks the bike i would be happy and he is doing a good thing because i dont want to be in a situation like someone checks the bike for me and asks for like 50. or something. Of course i do not want anyone to do it for free, its all up to them if they have some free time and wants to help on someone.

Thanks for your answer.

[MarJay]

Nobby is a good man, he's not far and he'll help for free.

Expensive oil isn't really important. Clean oil is, but with those pics I'd say the chain and sprockets is definitely the priority.

I'd change the coolant, air filter, spark plug, oil, oil filter (no point changing the oil without the oil filter) and the chain and sprockets.

I'd also do the following:

inspect the fork seals - make sure no oil is leaking out
inspect the brakes front and rear. Not too much dirt on the caliper, enough meat on the brake pads.
inspect the tyres, check they have enough tread and the correct pressures.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[JaniHun123]

Thanks for your answer.
I have changed spark plug when my last post was created (about 1-2 months ago). I'd like to change the air filter too. I wont change my oil without a new oil filter then, thank you for the info.

Edit: alright i googled the oil filter of cbr125. I will have to get one and talk with the mechanic then to change it as i was reading its in the engine somewhere(?)

Thanks

[Nobby the Bastard]

Why do I think it's all gone a bit arcane again?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[JaniHun123]

[Nobby the Bastard]

I can come wherever you are on Saturday if you like (PM me)
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[JaniHun123]

I have sent you a PM.
Its good at any time for me.

Thanks.