Teflon-Mike
tl;dr
Joined: 01 Jun 2010
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 Posted: 00:12 - 26 Oct 2015  Post subject: |
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Well, IF your ate's bike is the exact same model and year as yours...
either
- your mate's bull-shitting.. which is quite likely... few 4-stroke 125's can better (a 'genuine', as opposed to 'indicated' ... by the speedometer.... give or take however much needle wavers and bullshit tolerance whoever it's indicating to thinks they can get away with) 70 mph under their own steam....
Or
- Your bikes AREN'T the exact same model and year - bikes take months to get from the factory to a dealers show-room, and they can sit there even longer before any-one buys it, and the dealer sticks a number-plate on it... which means, you can, and quite often do, get two bikes, registered on the same day; and so get the same 'age' registration; but, one sold by dealer who sells more bikes, more quickly, could have been made that same year; one sold by another dealer who doesn't move so many for whatever reason; could have been sat n his shop for over a year, and been sat in a warehouse for six months before that, and on a ship for three before that, etc and have been made two years earlier, and be two 'model years' older, and so not have the same 'specification' depending on what the maker has changed i that time... often its only the colour scheme, and detail things like switches or the brand-name on the tyres... BUT, could be that they made a change to get the bike through regulatory requirements, like 'emmissions' that begged a smaller carburettor or something.
OR
- There is something 'wrong' with your bike... like seven years being thrashed, trashed and crashed by newbies on L-Plates!.. Old rule of racing, before looking for more than standard, make sure you have all you should AS standard... super-charge a clapped out engine with 90% of its life worn away, super-charger wont help much, 'extra' it might offer, will be mostly robbed by whatever is 'wear' is robbing the engine before you ft it, and all you'll do is wear out that last 10% of 'life' that much faster, ad a dead engine dont make ANY power, super-charger or no!
Last option...
You is one heck of a fat git!
However, your 8.7hp vs 13.5hp... query: - I doubt that the older models made anything LIKE an extra 4bhp.. I SUSPECT that they make nie on the same power, regardless of year... I suspect that the umbers have simply been quoted with the wrong 'units'... in metric, power is measured in Kilowatts (Kw), in old fashioned Imperial units, its measured n Brake-Horse-Power (BHP), and 9Kw is approximately 13BHP.. umbers are SO similar, aren't they, I'd lay money on it.
Which, prompts the suggestion, your bike, simply be a bit buggered... as far as I can tell, looks like its got an overhead cam engine, probably a copy of the Suzuki GS125 or Yamaha SR125 engine.. and those would be rated at 'about' 11bhp, I would be dubiouse of a 'copy' making even that much; few air-cooled 125 singles ever achieve much more especially ones that have been 'de-tuned' t get through this centuries ever tightened emission limits.... but like 'genuine' mph and 'indicated', you can run the same engine up on a dynometer and measure power six different ways, and get six different numbers, that you can then bung to different mathematical formula, to get umpety different 'standardised' power ratings.. ad they ad-men pick the most flattering to print i the sales brochures!
Real world, that engine 'ought' make 'around' 10bhp... and the bike 'ought' to be capable of about 60mph it.
If it don't do that, then I'd be looking for a fault to 'fix' to get e all it should have 'as standard'; and I'd start with the simple.. and start with asking you how you use the gears....
Hobby-horse of mine, BUT, old racing joke when rider asked mechanic what they could fit to their bike to make it go quicker, mechanic says "A faster RIDER!".. which is a truism.. and like super-charging a clapped out old knacker.. give a crap rider the BEST engine, they ent going to go much f any faster, and like as not, and again, like the super-charger analogy, all they would do, is crash sooner!
So these 'ere gears! VERY common newby error, is 'short shifting'. Changing up too many gears too soon, and being in top, by about 35mph. A Moped can go 35mph, and it only needs about 3bhp to do it, so a 125cc engine, with 3x that or more, can be making that much at 1/3 the 'max power' engine revs.. hence quite happy to chugg along that slow in that high a gear... just loath to go much faster, cos as you acclerate, the resistance to going faster, 'drag' increases faster than the force the engine makes going up the rev-range. To go faster then, like going up a hill, you have to change DOWN into a lower gear, get the engine spinning higher up the revs, where it has ore power and can use it to accelerate, and THEN yo change up, once you have.
In short.. you have to 'thrash it' a bit, and use the lower gears, and higher revs to get it shifting; short shift, and if you are n top before you are doing 50mph, chances are you WONT go any faster, and its a curiouse phenominon, that its so common, regardless of the actual bike, on 4T 125's.
So.. that's startg point. I f that don't find you any ore speed, then time to start looking at the nuts and bolts; but before gettg all exited about swapping carbs... try cleanig it!
Do a full and thorough 'service', and DONT liit that to the engine! Look at brakes and tyres and everything else! Ever pushed a car with a flat tyre? They don't roll very well! So if your tyres aren't pumped up, you are making the engine do more work, and you wont go as fast! Brakes? Designed to slow you down.. are they rubbig at all? Cheap floatig calipers are otoriouse for gettg gumed up and not always releasing properly.. AND back to that 'better rider'.. you aren't accidentally pressing the back brake peda while 'riding' are you? Either how you sit, or how the pedal is adjusted, or how you twist your foot when you corner... have a think, look at what YOU are doing...
Back to the bike.. oil change, spark-plug change; adjust the tappets; adjust the cam-chain tension;
Look at the drive chain... if the thing is rusty as fuck and never seen oil, then how much 'force' does it take to make the links move? Cos engine's having to do that work, before it can turn the wheel, and its acting like a 'brake' to stop you going as fast...
Seven Years of abuse by Learners.. what's the betting the chain is the one fitted at the factory, and has been knackered three times over i the bikes life-time; owner taking a link out of it to shorten it, each time they run out of adjustment to pull the wheel back in the swing-arm slots!
Odds are, the thing is in seriouse maitenance 'over-draft', and gettig the book, followig the instructins and doig all the 'service adjustements' and 'replacements' it suggests, will make the thig as 'good' and as 'fast' more, as ecconomical, and as RELIABLE as its ever going to get....
And IF there is some real fault in there; well, good chance doing the service items, good chance you'll find it, if not fix it! And if you don't? Well, making sure everything is as the book says it should be, is a damn good place to start 'fault-finding'.. having eliminated as many possible variables as you can, before you try, rather than stabbing randomly and hoping for the best by voodoo, guess work, and shear blind luck!
As for TUNING?!?!?
Just don't even think about it. Its a 'reliable & economical' 10bhp 4T, 60mph motocycle, if you dont want a 'reliable & economical' 10bhp, 4T, 60mph motorcycle... flog it to some-one who does and start some-where else!
Plenty of unreliable, un-ecconomical 125's about, that can, occasionally be persuaded go to a bit over 70mph.. but not much, and probably not very often, depending n how often they stop working all-to-gether! If you can live with that, buy one of them!
Takes about 3bhp to go 30mph, takes about 9bhp to go 60, to go 90, takes about 27bhp.....see the 'progression' here?
If you could double the power your engine might have made, as 'standard' when 'new'.. about 20bhp, it MIGHT nudge you up to around a genuine 80mph on a good day...
And I can tell you point blank, you will NOT find THAT much extra power, adding a pod filter and taking the baffles out the exhaust!
To get even half that much extra power, you would have to burrow deep into the bowels of the engine; power is proportional to how quickly the engine can burn fuel, and to do that it needs air, so more power demands more air, and to shift more air the engine has to be bigger and or turn more 'cycles'; and to let the air get there, it needs valves that are big enough to let that extra air n, and a cam that opens the valves far enough to let that extra air in, and THEN only THEN might such thigs as 'porting', makig the holes teh air flows through bigger or less tortiouse, do aythig helpful, and only after all THAT has been done, do you need to worry about carburettors, air filters and exhausts.....
D it, do it right, do it well, you MIGHT, after spendig an awful lot of time and money, achieve something in the region of 'ooooh!' 13 possibly 14bhp? Might be enough to see a genuine 70 a little more often, but.. net result... you have taken an old second hand, low-cost commuter bike, and probably spent as much money as buying a brand new Yamaha YZF-R125, to 'almost' be able to go as fast.. with probably little less chance of it not grinding to a halt!
If that little bit 'extra' is REALLY that important.. well, as sggested, flog wot yu got to some-one who'll apreciate it for what t is, and fnd the extra cash to buy a second hand CBR or YZF-R125 or whatever.. its less hassle, less effort, less money, and a garanteed 70mph, rather than just a sniff of a chance!
But start with how you ride it; work on that 'better rider', and THEN pay heed t the service procedures, and get all you should AS standard, and rather than look for more than standard, look for something that has ore as standard!
Tunig tiddlers is a feels paradice.. trust a fool for them on this one, I have loads of the little fuckers to fiddle with... it can be 'fun', but it is by no means in any way 'sensible'.
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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?' |
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