Any of the race replica 4T 125s will have about the same top speed as they all have the same power, similar gearing and similar fairing size that gives a similar frontal area for the air resistance to work on. So if you are after a 4T bike you may as well just go for the one you like the look of most.

2Ts are only unreliable if you dont maintain them. They also need a top end rebuild from time to time, which isnt as bad as it sounds.

 

im pretty sure he would love a yamahas YZF R125, but the CBR has a 1000 more revs and is just as quick, the CBR is much smaller but handles better and the CBR stock brakes are better than the yams brembos aswell..
yamaha is pretty tho, and pips the CBR in acceleration and will hold the CBR of at top end aswell if they dont slip stream ^^

 

Trouble with 2t bikes is unless you buy it new you dont really know if its been looked after. You can treat it fine but it can still blow up because the previous owner used cheap oil or a cheap piston.

So yeah, buy a 2nd hand one but then rebuild the top and bottom end of the engine to be sure.....thats a fair wack of work though.

As for the 4t bikes, they all go about the same. About 80 is what you`re going to get. I believe on a speed test the CBR125 got 72mph and the R125 got 78mph?? So yeah thats near 80 on the clocks.

I chased my mate on his XVS125 at 80 on my TZR (my tzr 125 restricted) and i was creaping up on him but we had to pull over to wait for someone on a GS 125 - now thats a SLOW 4t 125

R125`s are nice, but very expensive.

 

after having a race with a R125 the other day.
i can safely say it sh*ts all over the cbr 125.
its not masses more power but it seemed to get to speed quicker.
The bloke was a sh*t rider and i had to work really hard to keep up with him and eventually overtake him.

 

Acceleration is a function of power, gearing, weight and air resistance.

Top speed is a function of power and air resistance.

Rolling resistance makes a very small contribution in both cases and is effected by weight, tyre profiles, and wear and tear in the engine, gearbox, bearings and chain.

Air resistance is mainly effected by the frontal area of the bike, the physical size of the rider, and the type of clothing the rider is wearing. A rider fully tucking in behind the fairing will make a huge difference versus a rider sitting up.

Many owners change the gearing of their 125s by changing the sprocket ratios. This will either increase acceleration and decrease top speed or vica versa.

Given that the power (on two well maintained bikes), weight, and frontal area of the two bikes are very similar, the difference in performance between the two is down to gearing, rider weight/size/clothing (yeah that means you lard arse), and/or rider performance. Of course if one bike has just been serviced and the other is 4K miles from their last service with a dry chain and clogged air filter then the newly serviced one is probably putting out more power.

 

09 Derbi GPR

 

£££££££££££££££

Although saying that i`ve no idea how much they cost. Probably £3000? - would have to run it in as well.

You`d get a 2nd hand R125 for less i think. Some bloke on here picked one up for £1900 i think.

 

hang on "fastest" and "125cc 4 stroke" oxymoron?

 

Same could be said for 2t 125`s though....they all go about the same when derestricted. Sure some need a bit more work than others but in a straight line they all kick out about 26-29bhp and will do about 100mph.

 

Get him to do his test and sell him your cbr 400. Simples.

 

Most 2 strokes RS/mito/nsr can be bought and made good and reliable extremely affordably if you know what your doing.
Simple engines with only a few components to that need attention.
If you want a fast 125 it will have to be a 2 stroke and you will have to pull your head of of your ass and learn about what needs doing on them.
Easy, cheap and twice the power of a 4 stroke

 

if you know what your doing.

or have friends that do

 

Hyosung GTR 125 or w/e its called is prob the fastest 4t 125. A mate at college put a new exhaust on and it was a lot faster than my cbr...

Then he crashed it and replaced/resprayed fairings and put nos on it (lolol big waste of cash). To his credit he now has a mint '07 r6 in black

edit: just remembered looking at the pic he also put a dual front disc conversion on lol

 

fastest 4 stroke 125cc

Hmm, that's a bit like saying what's the best smelling turd... They are all sh*te so it makes no difference

Basically if you want performance you need a 2T or to pass test and get a bigger cc bike. If you go for the 2T, they need to be maintained, if you don't then they will keep blowing up.

If you're not into maintenance or don't want to do test then 125cc 4T is the only way left. But that's a bit like being out on the pish with a couple of mates, meeting 3 girls, your mates getting the decent ones and you being left with the fat skank no one would take a second look at

 

LOL Russ, i had the best picture in my head about that just now

Heres an idea OP, get your mate blandit, ride it uninsured, no problem at all. Here is another idea, dont ask stupid questions as you will recive stupid replies.

 

Did you go to St Trinians?

 

cheers for all the input guys.

as for the nobbber that wrote oxymoon "fastest 4 stroke 125..." you plonker, its a question, im not thick, ive done my time with 2 strokes, a third engine and lots of pistons etc and i decided to do the big test.
to buy a reliable big bike, which on my first night out after passing, hit a dead badger, (almost didnt see it as battery was running out) and then about to meet my misses (new at the time) it ran out of batt (rectifier had blown) and it broke down on the bypass, that was the start of my cbr400 nightmare - diffefent story.

My bro lived with me and watched me refit engines and pistons in the rain with a head torch, and he deffo doesnt want one (despite the speed benefits)
and he doesnt want to do his test yet.
By the looks of it 4 stroke 125 sports bikes and mental in price, you can get a used 400 for 700 smakeroonies but a 125 is almost 2k!!!!
safe riding anyhow and cheers for the entertaining comments,
its remiding me of how much fun i had on my tzr

 

Quickest 125cc four strokes (omg I said that in 1 sentence) will be R125 and Derbi GPR.. But only R125 you can get used.. They go for £2k ish now.
Personally I wouldn't spend that money on 125cc 4T, but that's what you are looking for - fastest 125cc 4-stroke.

 

If you were on your third engine then you didn't know how to look after your bike. Unless you owned it for a very long period of time and did more miles than concord, lol.

 

Sometimes they just break as well. They cant decide if they want to work or not, like they`re always changing sides, afterall most 2t 125`s are Italian

 

Probably the fastest 125cc 4t:

http://thekneeslider.com/archives/2008/05/30/honda-125cc-inline-4-cylinder-monkey-bike/

 

sounds like you've done your time and learnt absolutely nothing

 

Just go for pure looks - try one of these
http://www.megelli.com/sportbike.shtml#reviews
I think they look better than the other 125's out at the moment.
Would have got one myself but don't know enough about bikes in general to have risked it.

 

on the looks..
Looks a bit like a duc/ R125 on the front..

Wonder what that exhaust sounds like..

For those too lazy to click the link..

Wouldnt mind the 250 version.. Dont know about prices yet?

 

Whatever country it is.. Its 29,000,000 in their currancy.
Chinese, or something?

 

Jayzus I hope it aint that much

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£2500 isnt anywhere near new RS125 prices, so its better looking, better sounding and is cheaper.. WIN

 

Spot the difference

Personally I think £2.5mil is quite a lot for a 125

 

£2500 isnt anywhere near new RS125 prices, so its better looking, better sounding and is cheaper.. WIN

Live rates at 2009.10.16 23:50:58 UTC
29,000,000.00 CNY = 2,596,893.45 GBP
China Yuan Renminbi United Kingdom Pounds
1 CNY = 0.0895481 GBP 1 GBP = 11.1672 CNY
Erm .... FAIL !!!!

 

Beat me to it lol

 

Im made of fail, especially late at night..

It looks pretty decent, but hopefully its made cheaply, that way when it finally breaks, its cheap to fix. lol