yamaha sr 125 top end speed

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

hey im new to bike chat forums so my first post is here.

i have a 1991 yamaha sr 125 and im still on L plates (see my sig)

basically it was reving extremely high at 60mph in 5th gear, i thought i would solve that problem by going from a 16 inch to an 18 inch wheel with a high profile off road trye.

i also changed from a 49 to 41t sprocket, now my speed to gears is as follows.

1st: 25mph
2nd: 45mph
3rd: 65mph
4th: 85mph
5: unknown

the problem i have is 5th gear hasn't got enough get up and go to reach speed. unless im doing 85+ theres no point switching to 5th gear as i lose speed.

does anyone know the best setup for my wheel/sprocket.

i had the idea of getting a lower profile 18 inch tyre (90/90/18) which has around an inch less circumferance.

taking it to the equivalant to a 17 inch tyre. i wasnt sure if this would make a great difference.

whats your views guys?
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beerbelly · L Plate Warrior Joined: 23 Feb 2010 Karma :

is this a piss take ??? Rolling Eyes

binge · Emo Kiddy Joined: 03 Jul 2004 Karma :

0-60 in 6 months. Laughing

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

0-60 isnt too bad its just 60-85+ is slugish
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20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

binge · Emo Kiddy Joined: 03 Jul 2004 Karma :

If your SR125 does over 85mph+, I will actually go down on you!

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

UnspeedySam · World Chat Champion Joined: 26 Nov 2009 Karma :

Your speedo is clearly inaccurate. Get a friend in a car to drive alongside you when you're doing the top speed and see if their speedo says 85mph. It's unlikely you're doing over 70 in reality.
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Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
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Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

UnspeedySam · World Chat Champion Joined: 26 Nov 2009 Karma :

Ok. That is pretty cool. I'm still not sure I believe it though Razz

My RXS which is supposed to be a tad faster than the SR has a top speed of around 65...or 75 if gravity and wind is on my side.
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Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01, Honda Bros NT400 NC25 '88

binge · Emo Kiddy Joined: 03 Jul 2004 Karma :

My 70kg pit bike which has 28bhp of TZR125 engine stuffed up it, only just manages 81mph!

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

2 strokes. :/

mines a 4 but you have to take into account i have 18 inch high profile tyres with 41t sprocket.

ill video it at some point if i can Smile

i am quite impressed with it.
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GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

27cows · World Chat Champion Joined: 01 Nov 2009 Karma :

I once had an indicated almost 90 out of my RXS on its original motor (which was a quick one anyway). 16/35 gearing, chin on tank, down Jubilee Way in Dover, with a following 50mph wind. Bike was virtually unrideable in top gear under normal circumstances though Laughing

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Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

Howling TerrorOutOfOffice · Super Spammer Joined: 05 Dec 2008 Karma :

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Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

aww threds gone quiet.
still didnt recieve help regarding my sluggish 5th gear
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GOOD GAME BODYGUARD: https://i.imgur.com/8WePGgf.jpg
20:30:37 Pyro.: I don't sort of like men, I take every advantage to choke on dick.
Jewlio Iglesias: You live in Liverpool - Chances are, the front door has already been kicked off the hinges

RichP · Nova Slayer Joined: 05 Sep 2009 Karma :

I'd personally put it back to standard, my SR125 (which I wrote off, oops!) could do 75 down a pretty steep hill with the wind helping, and flat out in 5th would do about 57!

The one time I tried measuring the 0-60 It couldn't get TO 60 because of a mild headwind lol!

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

RichP · Nova Slayer Joined: 05 Sep 2009 Karma :

Yeah man, but the acceleration will be baaad! Even worse than before Very Happy

My best advice is to sell and get and NSR, or other race rep, I couldn't believe just how much better they are to ride, like chalk and cheese!

Pol Anorl · Banned Joined: 13 Apr 2010 Karma :

Highlandmav · L Plate Warrior Joined: 05 Nov 2014 Karma :

Hi everyone.

Can anyone tell me where I can get a pair of 18inch wheels to fit my Yamaha sr 125?

A bit of extra speed where I live would help me loads as I am unable to take the bike test due to lack of funds.

Thanks in advance.

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

monkeybiker · World Chat Champion Joined: 23 Sep 2014 Karma :

This has got to be one of the most stupid things I have ever seen. Changing sprockets ok but changing wheels, wtf.