lack of top end power ?

[barnesy213]

basically i have a lack of grunt towards the top end ,, my bike is a 2009 honda cbr 125 FI version

basically getting upto 50mph is fine but after that it seems to be struggling to get any higher , i always run it on high octane petrol (shell v power)

i'm thinking it could have a dirty air filter , but the bike has only done a little over 9,100 miles , the chain is at the correct tension but a little under-lubed

dont know what else it could be apart from a dirty air filter ,,, bearing in mind that i've had 82 mph out of this bike before and it might just be me being paranoid that somethings about to blow on the bike , but it could also just be the way the bike is seen as its a pretty light bike and gets blown around in the wind

any one have any other suggestion of what it could be

thanks Alex

[Carvel]

[Rogerborg]

[Ariel Badger]

[barnesy213]

[quote="Ariel Badger"][quote="barnesy213"] i always run it on high octane petrol (shell v power)

[/quote]
Please stop doing that unless you have upped the CR to above 9:1.[/quote]

What's wrong with running it on v power surely it's got to be better than ordinary supermarket fuel

[Pete.]

[Fisty]

[Rogerborg]

[monkeybiker]

You mentioned the wind. Were you heading into strong head winds at the time?

Were you going up hill?

Sorry but sometimes these questions need to be asked

[P.addy]

As said above, air filter, plug gap, last oil change including the mesh filter?

Run on normal fuel, it doesn't care.

You had an indicated 82 which means you probably did a real 70/71. That is really as good as it gets.

[stevo as b4]

As above. The OP's 82mph indicated must have been downhill/tailwind assuming it's a not a +10mph speedo?
Superbike tested the CBR125 at 71.3mph, and the YZF125R at just over 73mph. These are true speeds and on the flat are really good for 13bhp and 14.6bhp respectively.

You should be happy with what you've got 4stroke 125cc wise, as 70-75mph is the holy grail for such bikes, and a good +10-15mph step up from more basic unfaired commuter machines, like the YBR/CBF CG etc.

[BMWilliams]

New oil filter and spark plugs, then just use the regular fuel and I'm sure it will be fine.

If I'm Honest, I used to work for shell and v power really isn't anything special, especially for motorcycles, they just make it sound really good for a bit of profit. plus the higher octane means it needs a higher compression so the 125 might be having difficulty achieving this.

Did the problem start when you started using just premium high octane fuels?
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[DanRLee]

Go on a diet.
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[Kickstart]

Hi

[Teflon-Mike]

Use the revs, not the gears!
This is VERY common 125's when Learner, 'short shifts',and is in 'top'gear before 50mph... the bike has the power at those low revs to hold 50, but not enough spare to accelerate. You have to change down a gear to get the revs up, where the engine is making more power, then, when you have got the road speed up, and the engine revs up, so that when you change up again, the revs don't fall down so low, you are out of the power again.
Use the revs not the gears...making unnecessary 'up-shifts' is just making work for yourself, making them, AND the consequential 'unnecessary' down shifts to slow back down again, when, you could, in a lower, more responsive gear, do it ALL on the throttle.
Does the CBR have six gears? 5 or 6, though Top will almost certainly be an 'over-drive' gear; the ratio will be too tall, for the speed the bike can go with the power it has; you use it, to drop the revs back for ore relaxed cruising, or to eek out a little extra speed on a long hill or with a tail wind or something. Forth or fifth will be your usual gear for going fast, and then, only when you are on roads where you aren't likely to have to change gear very often.
I have CB125 Twins; they have a five speed box, but, I'll use 1st almost oly to pull away; its a very low gear, ad low enough to not make the bike labour, should I have to do a hill-start on a steep hill, with a pillion passenger... o the flat, I could probably pull away 2nd, but, it would n't be any smoother, so I don't. Tops out at about 20mph in 1st, so I am chaging up to 2nd almost as soo as I am moving at more than a brisk walking pace; 2nd will then take me to around 30mph, so 'round the houses', in 20/30 limit urban areas, where I am probably riding along short stretches of residetial housing, with potential for cars backig off drives, kids kicking balls in the road etc, where there's cul-de-sacs ad juctions every twenty yards, ad I am probably gong to have to change speed to negotiate a give way, or stop,LITTLE point changing 'up', makig work for myself, to go up, and come back down, and to deny myself of what little throttle 'response' the bike has, JUST because I have a lever there and so think I ought to do something with it, or so it does't SOUND like I am making the engine 'scream'... Out in the traffic flow, in town? Again, 20-30ish limit, junctios are likely to be further apart, ad traffic is likely to be flowig a little faster, here 3rd gear becomes the 'mother of all work'.. gives me the throttle response to slow to as little as 15mph ad still have some 'oomph' to accelerate if I have to, but will pull to about 45-50 comfortably enough, if I wind it on. So I can do almost everything, in ONE gear, with as much 'response'; as I can have to do it all on the throttle, not making work for myself playing tunes on the gears, or unsettling the bike any with all the changes 'load' cloggig up ad down the box; its smoother, safer ad easier. AND saves wear ad tear on the bike! Once out of town, and onto 50ish roads, THEN I'll sick it up to 4th, if I am goig to hold that sort of road speed, and I'm not faced with so many 'hazards' by way of house drive ways, or side junctions etc likely make me have to change speed too dramatically too quickly, and on the 125 Twin, 4th will take me to about 65 at the red-line, almost as fast as the bike will go; so unlessI am on a duel carriageway of fast sweeping A-Road, I might 'eek' that bit extra from the thing on.. it'll probably stay in 4th; sknicking up to top will drop the revs back at 60+ and could carry me up to the bikes terminal velocity of a nadge over 70, in 'favourable conditions' but its a lot of effort for not a lot of gain.

Its a little bike, with little power, and what little power it does have, is mostly at the top of the rev range, you HAVE to use the full rev rage to get the best out of these little bikes, and you do have to work the gears, but not OVER work them.

So chances are theres nothing wrong with the bike, you just need to make it work for you, and use the revs not the gears.

As for the petrol? As has been said; there's nothing in higher octane petrol that will make your bike, as Hoda made it, go faster.

The octane rating of a fuel is merely a measure of how much cylinder compression it can stand before exploding, and doing damage to the engine, rather than burning and making useful motion. The cylinder compression is set by the volume of the combustion chamber above the piston, in relation to the displacement of the piston in the cylinder. Anf f Honda have fixed a compression ratio that s 'safe' for 94 Octane 'regular' petrol, then, 97 Octane 'premium' is't doing anything helpful for you.

Whether using a 'brad-name' fuel, which may or may not have a better formulation, with more or better 'detergents' in it that don't leave as many sot deposts and shit inside the engine... who knows...

As for 'Super-Market' petrol? Well, petrol does have a shelf life & goes stale with age; AND little known fact, but there are legal requirements for the sale of petroleum, and one of them is that for the UK there are two 'standards' for petrol; one for summer, and one for winter; ad retailers have to show they have swapped the 'blend' in their tanks twice a year, between set dates.

I suspect, as I have little but hearsay evidence to go from that a lot of the controversy or suggestion about 'Shit Supermarket'petrol, is simply super-marketing, stack it high and sell it cheap; and them buying whatever they a get the best price on at any one time; and that is likely to be 'old' petrol, nearing its sell by date; whether 'last seasons' mix, or this getting stale, or nearing its sell by date, rather than to do with any magic potions included in a 'Brand Name' Blend.
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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?'