Derestricting my derbi mulhacen 125 cafe

[Chewy2008]

Hey guys, i own a derbi mulhacen 125 cafe and i was wondering if anyone has any tips on how to get the most out of it? Ie: derestricting it or changing sprockets n exhaust. Many thanks

[wr6133]

You need to get a red powerband.

[Nexus Icon]

Lay off the pies.
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[Skudd]

Learn to ride. A bad bike ridden well is far better than a good ridden poorly. Keep your bike stock and save for those lessons, tests and then a bigger bike.
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Petty Anarchists look at "1984".............. The Visionary looks at "Animal Farm".

[Rogerborg]

Trade it in against a Varadero or YZF R125.

Or just sweat it out until you're 19.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Northern Monkey]

A slightly larger screen will add about 3 or 4mph, even more if you tuck behind it. It'll look shit though.

The majority of drag in bikes is from wind resistance. Any steps to reduce this will increase your maximum speed.
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Fisty: after polishing the tank with the glistenng beads of sweat from my full hot scrotum, I filled the headrace bearings with 10cc of my manmilk

[RhynoCZ]

How long do you own the Derbi?
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[The Shaggy D.A.]

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Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[wots]

On a rideout with Paddy on his Varadero, SQL had one of those. At one point he was leading and through the twisty bits it was fetching good speed for a 125. There was a couple of times on my old NTV600, I was having to get on it a bit, more than I thought I needed to.

Save money, give it a damn good service, which can gain a bit of performance. Make sure it has good rubber and plenty of it, then you can use the speed you have.
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Currently: Yamaha DT 125 LC2,Repsol Fireblade, and Bumblebee MSX 125

[Northern Monkey]

[RhynoCZ]

[SQL]

on the limiter i would get 76 indicated, you must hit 10k in 5th before changing to 6th or it won't pull the power

[stevo as b4]

Who told you it was restricted or was in dire need of a gearing change?

Best advice I can give is shoot the cunt dead!

[andys675]

[Dave M]

[Chewy2008]

Im 37 not 17. Im riding 125 on L plates to get my confidence back on two wheels after a head on collision when a car pulled out on me 18 yrs ago! Now as im gettin comfortable on 2 wheels i want to be able to go faster than 58mph and be able to get upto speed quicker

[Teflon-Mike]

To be able to de-restrict a bike, it has to first be restricted.

Its a four-stroke 125 built to A1 licence requirements, ie 15bhp, so the chances are it s what it is, and if you want more than what it got, you are going t have to conventionally 'tune' it; there's no magic bung the exhaust or chip i the ignition that you can tinker with to mystically liberate oodles of power the government don't want you to have.

Now; conventional tuning may be possible;
Power = Cylinder Displacement x Cylinder Pressure x Engine Revs.
And the key is 'Cylinder Pressure'.. which you get fro getting as much charge in the cylinder as you can each cycle; 'charge' is air + fuel, and by volume its about 99.99% air, so we are talking about getting bigger volumes of air to the engine... ad while ost people look at the size of the carb ad the 'ports' ad the exhaust ad thik "Ah! Bigger, must flow better'. the pinch-pot i the system tends to be the valves.

Single Cylinder 125 will tend to have a piston around 54mm in diameter... 'cos a 54mm bore ad 54mm stroke is what's known as 'square' dimensions and gives 123 point some-odd cc of displacement. NOW that single dimension says how big you can make the valves that sit above it. two-valves, you are looking at perhaps 26mm inlet and 24mm exhaust, taking 50mm of your 54mm cylinder diameter, ad leaving maybe a mm of metal either side... Of course the area that you can flow air through will be even smaller, after you have taken out the space needed for a lip for the valve to seal against and a stem down the middle to push it open; but lets ignore them for a moment.. you can make the carb as big as you like; any bigger than 26mm and it'll flow more air than the valve at the end, so not likely to help you much; ditto the 'ports', bigger cross section than the valve, make them as smooth as you like to avoid turbulence, BUT.. if that valve is in the way.. not going to help any...

So, if you want to 'Tune' a four-stroke, you really have to get INSIDE the engine and start dong real engineering... making them valves bigger and or opening them sooner, faster and further, so they are letting as much charge in the cylinder as they can...

And quickest route to more power from a four-stroke engine has always bee a 'hotter' cam-shaft profile to do just that, and probably the easiest mod to make without pulling the engine totally to bits.

Now, according to google, specs suggest our ike has a water-cooled, four-valve four-stroke single engine, and kowig the Derbi-Yamaha partnership I'd hazard that means its the YZF-R125 engine, for which you might find some 'tuning goodies; including a cam-shaft ad perhaps a big-bore kit; but fro what I have heard, chucking half as much again as a YZF-R125 costs new the show-room, so we are talking a couple of grand here, not a couple of hundred, and doing a very detail 'build' in a pro-workshop, not a week-end on the patio with a Argos 1001 piece socket set, result in a WOPPING 20% increase in 'peak' power..... sounds impressive, but that's still only 3bhp..... That is as much as a moped makes more.... but it's still not going to be enough to start scaring motorway speeds very much.

Which is all 'leading' advice... hopefully to the conclusion that its an utter waste of time, trying to tinker with tiddlers for ore speed.

I do it.. but specifically AS a waste of time.... paint a bit of old 125 Super-Dream, leave stripped carbs lying around the kitchen, other half is happy, knowing I'm not messing with other women, sort of thing... but it is still 'futile'....

A-N-D.... so we get to the nub of the matter.....

[MarJay]

Tef, I can distil your post down to a couple of sentences.

It's a four stroke 125, it's not restricted, it currently makes the maximum power it's going to make without paying a shed load of money for no gain.

The best option would be to sell it and buy a faster bike.
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[The Shaggy D.A.]

[P.]

[Northern Monkey]

[SQL]

[stevo as b4]

I wasted £600 on tuning a Pug speedfight 100. Granted it was crap basis for tuning, but it was fun messing with it to a point.

I already had a 100bhp bike sat in the garaged and taxed at the time.

But If I had £600 available right now, I'd probably spend it on a DAS course with a good school and maybe 1-2 additional/advanced lessons thereafter.

When you have licence, insurance funding, and all running costs covered for any said bike you want to buy, then you can spend the next chunk of cash on the tart factor, or pursuing bhp for lolz!