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How to up the speed on my 125??

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Mark2910
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Joined: 16 Jun 2012
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PostPosted: 16:08 - 23 Jun 2012    Post subject: How to up the speed on my 125?? Reply with quote

Hey guys,

I know my little 2007 Keeway Speed 125 is a crappy cheap chinese hunk O'Junk compared to the Yamaha's, Aprilla and Honda 125's but I've been reading up and watching some clips on Youtube about 125's doing 80mph.. i know mine will never achieve such a dizzy height of 80 as i 6ft 2 and the best part of 18 st.
Mine tops out at 57mph (downhill) on the speedo, I've read changing the front sprocket etc, Air filter etc but my mechanical Knowledge is limited and I don't want a major job of engine out cos frankly is isn't that important as i will get around to doing my bike test and getting a "bigger" bike but i would like a little more knowledge of tinkering with bikes before i do the test.
I've checked and its a 15 tooth front sprocket, looks standard rear, No idea how the Carb is set up either or how to adjust it...

Cheers Thumbs Up

Mark
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arena
Two Stroke Sniffer



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PostPosted: 17:49 - 23 Jun 2012    Post subject: Reply with quote

It's really not worth your time.
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numpty2
Trackday Trickster



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PostPosted: 19:14 - 23 Jun 2012    Post subject: Reply with quote

It really isn't worth it, especially given your size. There are fundamental laws of physics at stake. Another thing to consider is braking. I had a CG125 for many years, and what stopped me exceeding 55mph was the braking experience.

But you could do your own servicing. This qualifies as tinkering, and the sooner you start the better. You will learn & save at the same time.
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Derivative
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PostPosted: 19:31 - 23 Jun 2012    Post subject: Reply with quote

What you need is one of those 126's. Almost 1% faster.
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Pete.
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PostPosted: 20:02 - 23 Jun 2012    Post subject: Reply with quote

Derivative wrote:
What you need is one of those 126's. Almost 1% faster.


You get more gains with a red power band TBH.
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symonh2000
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PostPosted: 20:10 - 23 Jun 2012    Post subject: Reply with quote

This is the main problem with 4 stroke 125's... They are generally tuned to a specific power output rather than restricted, and are much harder to get more power out of them unlike a 2 stroke.

Maybe a free flowing airfilter and exhaust would be a good start, but to get serious gains you will need bigger valves, porting and maybe a different profile cam. Rather like you would do to a car...

It isn't really worth it IMO.
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Mark2910
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PostPosted: 21:00 - 23 Jun 2012    Post subject: Reply with quote

symonh2000 wrote:


It isn't really worth it IMO.


Okay, was just thinking of filling my weekends with a learning curve.. and trying to improve the bike at the same time.. Never mind.. I'll bring forward the Bike test then Smile
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Mark2910
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PostPosted: 21:03 - 23 Jun 2012    Post subject: Reply with quote

numpty2 wrote:


But you could do your own servicing. This qualifies as tinkering, and the sooner you start the better. You will learn & save at the same time.


Yeah gonna start doing this.. was hoping to learn some something so i wouldnt rely on local garages and friends for help.

Cheers Smile
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numpty2
Trackday Trickster



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PostPosted: 21:20 - 23 Jun 2012    Post subject: Reply with quote

After your first DIY service, when you have got grazed knuckles and oil spills up to your armpits, you'll convince yourself it runs faster.
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MarJay
But it's British!



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PostPosted: 22:02 - 23 Jun 2012    Post subject: Reply with quote

What I said wasn't a flame... but whatever.

Seriously when it comes to four stroke 125's then the best way to go faster is to get rid of it and buy a bigger bike. Or, buy a two stroke 125 and de-restrict it...

I think you're better off doing your test and buying a bigger bike. Tuning is often a fallacy anyway. You need to spend thousands to get a small percentage gain, but 10% of 12bhp is only 1.2bhp. 10% of 160bhp is 16bhp. Hence its better to spend money tuning on bikes that are powerful in the first place...
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; American Iron: Buell XB12R; Track Hack: CBR600RR-8
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.
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Lord Deckard
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PostPosted: 22:31 - 23 Jun 2012    Post subject: Reply with quote

Derivative wrote:
What you need is one of those 126's. Almost 1% faster.


Got Spinal Tap in my head now Smile
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Teflon-Mike
tl;dr



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PostPosted: 02:05 - 24 Jun 2012    Post subject: Reply with quote

_Iain_ wrote:
Fresh oil,

24 for a 4l can will do 3 changes
_Iain_ wrote:
fresh air filter

10 will last as long as the oil
_Iain_ wrote:
fresh fuel filter

Doubt it has one! Clean cause on pet-cock on soapy water... job jobbed
_Iain_ wrote:
new spark plug

4 will need another when the oil runs out
_Iain_ wrote:
. Gap the plug to whatever its sposed to be set at, get the valve clearances done too while you've got the feeler gauges out.

16 for Haynes Chinky Bike manual to get the numbers from.....
_Iain_ wrote:
Clean the chain, clean it realy realy well, lube it well with some decent lube and set the tension just right.

4 for oven cleaner from super-market
10 for proper chain lube
_Iain_ wrote:
Set the tyres to the correct pressures.

5 for pretture guage you can rely on
10 for a pump

Congratulations you have just spend 83 of the lads money, to help him achieve MAYBE 55mph..... and he could have bought another one for that!

_Iain_ wrote:
a neglected engine wont do shit when you push it past the limits.


A Chinky motor wont do very much more even if its fettled by an ace!

I cant remember, Keeway, Skyjet & Superbyke; have a feeling that one of them hides a bloomin pit-bike engine behind its fancy plastic! Its not even as powerful as the CG copy motor versions.... loads 'tunable' and loads of tuning bits for them though..... same with teh CG engines... people get good results from them as well...

Bit like old VW Beetles... many a time have I heard folk claim that they have got 50% more power from them making 'simple' mods....

Yes, but 50% of fuck all is just a a bigger fuck-all, innit! Fact that they can get such big % gains is simply that they are so dire to begin with be hard to make them worse!

NO 125 is ever going to be 'fast'' even full-power not learner-legal two stroke sports.... not compared to big-bikes.

125 Four-Stroke? You are never going to get more than 'a bit brisk'.

CB125Twin, was THE most powerful 'standard' production 125 four-stroke ever built, I believe, 1977 and 17bhp..... did 80mph at a push!

I have had the de-tuned 'learner-legal' 125 Super-Dream 'off the clock', reading something well beyond 80, pointing about where 90 might be on the dial if it was marked..... genuine GPS reading of 70.

And I DOWN geared it to get that.......

Its about as 'quick' as you are ever going to get a 4-stroke Learner-Legal to go.

Jap brand Commuters, like the YBR, with only 10bhp to play with, in GOOD fettle will be lucky to nose past a genuine 65 very often....

The Chinky ones? Well if you can get a GENUINE 55 from them you are doing pretty good.....

As for tuning them?!?! Forget it!

Can be done, but as said, gains are TINY for the effort, and you are chuking money at something that aint worth bog all to make it even LESS valuable, and LESS reliable... which given these things notoriety for requiring attention, is rather like giving up and saying "Pah! Well I DONT expect you to work ANYWAY... so may as well see just how SPECTACULARLY you can break down on me....."

Wry humor? How to make a Chinky bike go faster?

Buy an AA Card.... It will do 56mph on the back of the recovery truck!
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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?'
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luckatme85
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PostPosted: 12:23 - 24 Jun 2012    Post subject: bad idea!! Reply with quote

hi probably a bad idea but if you look on ebay you can buy big bore kits for these very cheap, i had one on my chinky it was ace made it shake and rattle even more than before and nuts and bolts needed checking more regular. i gained roughly 7mph top end with bigger carb and i kept standard airbox with a chopped exhuast with no baffles, sounded ace popping back but then when someone on a tuned 125 scooter wanted to race you it got very embarrasing. tbh though it felt like i was doing 90mph instead of the indicated 70mph, but that was only coz of the rattling and shaking. the scariest part was wandering if it would fall apart, very scary and tbh a waste of time and money, either buy a 2t 125 that will be much quicker for you or get your test done.
from experience i think keeway are one of the better made chinky bikes and they do get quite good money on ebay and gumtree and the likes so sell it and buy yaself a cheap 2t 125, just dont make the mistake i made with my ts125r, i cant get parts for it very easy so go for something you can get parts for easy, dtr have one of the most reliabe 2t engines around but expect to pay quite a lot for one, if ya get one for less than a grand you will be lucky, theres a few nsr, tzr, rg's about have a look
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Alpha-9
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PostPosted: 12:24 - 24 Jun 2012    Post subject: Reply with quote

numpty2 wrote:
After your first DIY service, when you have got grazed knuckles and oil spills up to your armpits, you'll convince yourself it runs faster.


So very true Laughing Laughing
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CG125 faggot. Robbed 20/3/14 Reclaimed 24/3/14 Theory Mk2 - 15/9/14 Mod 1&2 Mk2 = 17/10/14 Such pass, much license. Wow. The XJ600 LIVES...just Aaand i've killed it a bit again.
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nightshaddow
Nearly there...



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PostPosted: 13:00 - 24 Jun 2012    Post subject: Reply with quote

these things can be upgraded to your benefit but the legality of some of the upgrades is questionable and the price is also the same

150cc bore kits are available and will give a little extra for around 60
30mm carbs fitted with 110 main jet and pod filter also helps 30
changing sprockets will help with acceleration or top speed

how much do you want to blow to get the results
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"WHAT DO YOU MEAN 100 MPH THATS IMPOSSIBLE Its chinese OFFICER."
Current rides CB 125 TDE(the next project) NS125RK ( now on the road ) CB125TDC (soon to be project 17) melody ( the nephews )
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Knightsy
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PostPosted: 13:04 - 24 Jun 2012    Post subject: Reply with quote

nightshaddow wrote:

changing sprockets will help with acceleration or top speed


I agree with that. Mate of mine has a chinese 125 cruiser and after changing rear sprocket he swears he got extra 10mph. Now I'm not sure how accurate he is, but you may want to give it a shot.

Don't expect epic results though, it's just 125 after all :/
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Alpha-9
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PostPosted: 13:07 - 24 Jun 2012    Post subject: Reply with quote

Knight wrote:
nightshaddow wrote:

changing sprockets will help with acceleration or top speed


I agree with that. Mate of mine has a chinese 125 cruiser and after changing rear sprocket he swears he got extra 10mph. Now I'm not sure how accurate he is, but you may want to give it a shot.

Don't expect epic results though, it's just 125 after all :/


It'll be either more acceleration and less top speed, or more top speed and less acceleration, upping number of teeth on the rear sprocket will do the latter, I believe
____________________
CBT - 14/01/12 Theory - 21/7/12 Mod 1 = 18/2/13 Mod 2 = 17/4/13 Revoked 11/7/13
CG125 faggot. Robbed 20/3/14 Reclaimed 24/3/14 Theory Mk2 - 15/9/14 Mod 1&2 Mk2 = 17/10/14 Such pass, much license. Wow. The XJ600 LIVES...just Aaand i've killed it a bit again.
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stevo as b4
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PostPosted: 13:11 - 24 Jun 2012    Post subject: Reply with quote

TBH i wouldn't reccomend a fragile sports two stroke for someone who isn't very mechanically minded or knows much about maintainence and servicing. And i wouldn't reccomend the same bike for the larger sized rider either, as i think you could end up with an even more fragile motor then and one that isn't going to achieve the performance than is sometimes claimed for these kind of bikes with a little under 10st Italian rider, with fully race leathers, down hill on the Autostrada, after hours of fettling and tinkering with the bike, and running it on Super/high octane benzina etc.

The OP seems to have very sensible attittute towards saving up to make the next step and passing his bike test. He will probably gradually learn a bit about mainatainece as he goes, and im sure he knows already really that more cc's in a bigger better handling and better braked bike are his best friend.
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nightshaddow
Nearly there...



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PostPosted: 14:52 - 24 Jun 2012    Post subject: Reply with quote

Alpha-9 wrote:


It'll be either more acceleration and less top speed, or more top speed and less acceleration, upping number of teeth on the rear sprocket will do the latter, I believe


frount sprocket up or rear down teeth = top speed

frount sprocket down or rear up = acceleration
____________________
"WHAT DO YOU MEAN 100 MPH THATS IMPOSSIBLE Its chinese OFFICER."
Current rides CB 125 TDE(the next project) NS125RK ( now on the road ) CB125TDC (soon to be project 17) melody ( the nephews )
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Teflon-Mike
tl;dr



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PostPosted: 19:44 - 24 Jun 2012    Post subject: Reply with quote

_Iain_ wrote:
I'll be sure to remind you next time you have a rant about "neglected learner bikes" that you've just practicly advised the guy not to service his bike, and not to clean and lube the chain. Rolling Eyes


I know, ironic ent it! I wasn't saying DONT do it... merely pointing out the ecconomics....

Go hunt out the 'service-spares' you need, and yeah, buy a half litre of oil at a time, they weigh up 'VFM' of a four liter bottle.....

Tally up your shopping basket, and at 90-100 on a 200 Chinky bike, you are on the threshold of it being 'Beyond Ecconomic Repair'!

Not that servicing isn't worth doing..... but on low value chinkies, more a question of whether ANYTHING is worth doing! Rolling Eyes

nightshaddow wrote:

changing sprockets will help with acceleration or top speed
Knight wrote:
I agree with that. Mate of mine has a chinese 125 cruiser and after changing rear sprocket he swears he got extra 10mph. Now I'm not sure how accurate he is, but you may want to give it a shot. Don't expect epic results though, it's just 125 after all :/
Alpha-9 wrote:
It'll be either more acceleration and less top speed, or more top speed and less acceleration, upping number of teeth on the rear sprocket will do the latter, I believe


Bigger the rear wheel sprocket, smaller the gearbox sprocket, 'lower' the gearing.

Smaller the rear wheel sprocket, bigger the gearbox sprocket, 'taller' gearing.

lower gearing = higher acceleration

taller gearing = higher top speed.

IN THEORY.

But, speed is an expression of 'power'.

Power = Force x Speed.

So Speed = Power / Force

Riding along, force you are working against is 'Drag', force you have shoving you is 'Thrust'.

And this is where it gets complicated!

Engine has a power curve. As the engine revs increase, so the power it makes increases, gets to a 'peak. then starts to drop off.

Coming from the engine, Power is Torque x Revs....

Gear up, and you increase the rear wheel revs, but you reduce the 'Torque' which is whats giving you the 'Thrust' to punch your way through 'drag'.

So, if you up-gear, it WONT necessarily make the bike any 'faster'.

Because the 'Thrust' you get from the motor isn't enough to over come drag... so the bike will actually go SLOWER.

Conversely, if you lower the gearing, you will increase the 'torque' and hence thrust at the rear wheel, which COULD give you some entra force to overcome drag and go a bit faster....

BUT depends on the shape of the power curve, where 'peak' power is 'made' and how much is drops off either side of that peak.

If you gear too high, then you will never get the engine to rev up to peak power and deliver full-force

Gear too low, you will run out of revs before you reach a road-speed where you lack 'thrust' to go any faster.

So to get 'best speed' its a question of finding the 'optimum' and finding the exact gear-ratio that gives you exactly the 'speed' that has the 'Drag' you have the power to beat....

Most bikes as standard are USUALLY slightly 'over-geared' so that the engine revs are knocked back for more relaxed 'cruising' at a speed a lot below thier pottential maximum.

So its more often that LOWERING the gearing, not only increases acceleration, but CAN see a few clics of extra speed.

BUT, thing to note is that GEARING doesn't 'set' how fast you can go...... but POWER.....

You can mess with years as much as you like, unless you have the engine power to make the THRUST force to shove you along that fast, you will NEVER go any quicker.
____________________
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?'


Last edited by Teflon-Mike on 20:11 - 24 Jun 2012; edited 1 time in total
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Mark2910
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Joined: 16 Jun 2012
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PostPosted: 20:08 - 24 Jun 2012    Post subject: Reply with quote

thanks for all the replies, will get a bigger bike once i sort a week off and get the test done and dusted. Got a quote for a Suzuki SV650 with a full bike license from carol nash, so thats my new plan.. i'll leave the 125 as it is, i could pour note after note and it wont be any better.

Cheers for the great advice Smile
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Old Thread Alert!

There is a gap of 6 years, 77 days between these two posts...

L33n
L Plate Warrior



Joined: 23 Aug 2018
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PostPosted: 08:15 - 09 Sep 2018    Post subject: Reply with quote

Mate half of these are chatting sh*t & hating on the newbies!
I have a keeway txm 125cc sits at 92mph nicely, Although its more like 85mph still decent speed for 4stroks 125cc.
Upjet carb straight threw airfilter retune carb properly as they mixed rich anyway, get rid of the cat. add bigger down pipe bigbore exhaust & sprocket change & maybe ecu remapping cost you 100 max eBay if want to push the boat out upgrade clutch plates & springs & do it yourself.
Don't go to big on down pipe, you will loose power not gain.
24 for 4L oil isnt good oil at all lol go something decent castrol racing power 1 14 1L if bikes upgraded & fast flow oil filter as everything will be moving faster due to upgrades ect. Don't tan the crap out of it look after it & you won't have a problem.
Mates done a CBR R 125 & his the same. Obviously after 65mph on a provisional you are braking the law so don't be stupid is my advise just some info on power gains without spending stupid money ect
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