Jprimus0910 Posted May 10, 2015 Share Posted May 10, 2015 Hi all im new to the forum, i have done quite alot of searching online and haven't found what im looking for so hear am I. Ok I have looked around and seen people saying they get 80+ out of the bike I understand 4 strokes are not restricted physically, but are they restricted electronically ? The reason I ask is I was travelling down hill tucked in, my speedo went to 75 then back to 74 and wouldn't budge as i was still going down hill and wasn't on rev limiter ? My other question is it would be nice to get a bit more acceleration out of the bike for overtaking purposes. Could I change either sprocket to gain acceleration ? I know if you gain acceleration you lose top speed but 'if' its restricted electronically to 74 I'm not too concerned about top speed. Any help would be great thanks Link to comment Share on other sites More sharing options...
slice Posted May 10, 2015 Share Posted May 10, 2015 You can change the sprocket, if you go smaller you get better top speed and less acceleration if you go bigger you get better acceleration and less top speed. Bit of a trade off but easy to do, as for "how fast will my bike go" it's a 125 so your about at the limit, you could lose weight take the junk out of your pockets or strip everything you don't need off of it to get a few more MPH but really how fast do you want to go on a 125? We have had loads of folks on here who want to get really high MPH out of their bikes and we always tell them the same thing, pass your test and get a bigger bike, the reason is simple if you thrash the shit out of your bike till it's screaming in agony it will blow up, not straight away and it might even last a few weeks but it will destroy itself eventually, no matter how much you spend or how good you are at maintenance it has a limit and if you pass it your gonna be stuck at the side of the road waiting for a big yellow truck. If your in the 16 to 20 year old age range then your going to ignore me and say I don't know what I'm talking about and you know best, ok fine by me but most of us on here have been where you are now and from personal experience I can say treat your bike with respect, accept it for what it is and deal with the bike as a whole, don't try to "improve" it, cos if Yamaha could make a cheap 125 that would do 100+ MPH they would. 1 Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 10, 2015 Author Share Posted May 10, 2015 Thanks for reply, i completely understand. thing is i'm not looking for more than 74mph dont care much for doing more than that as it seems to be capped. Sorry my first post may have been misleading and making out as if i want to do 100+. I am just looking for a bit more acceleration. I like the reliability and the economy which is the main purpose for this bike and pretty much every 125 on the market, its basicly a learning curve but too many people try push them past the limitations of the engine and like you say end up blowing them up quick. Does sound stupid yes I should go for bigger bike and save money rather than spending loads on small so called improvements to speed while sacrificing reliability. Little background on myself im 28 5ft 10 at just under 11 stone, my daily 30 mile commute to work consists of dual carriageways with quite alot of head wind and struggle to keep bike up to 50 without dropping gears frantically. Yes big bike would be ideal i have only been biking for a little over a year but the weather in scotland is NOT great, struggle to get half decent weather for biking. I have done my theory and had lessons on a yamaha rn6 while on holiday from my work. I work 6 days a week and cant get lessons on weekends not many riding schools that does evenings unfortunately, so i thought a bit better acceleration would help make head winds a little easier. If that makes sense ? Thanks Link to comment Share on other sites More sharing options...
slice Posted May 10, 2015 Share Posted May 10, 2015 Yes that makes perfect sense and you should be fine with raising the tooth count on your bike but even if you go for 1 or 2 more teeth on the sprockets your going to be revving the nuts off of your bike, it might seem an easy out to get better acceleration by fiddling with the gearing but it was designed to work in a certain way but it will work best at it's optimum gearing ie what you have now. I know it's not what you want to hear but leave well enough alone cos fiddling with it will make the bike less than it is now, 50mph isn't much I know but it's better than walking or catching a bus. Your not too heavy for it and your not in the "STUPID" age range so patience is your friend, stick it out till you get another bigger bike and use this one to learn to survive, it might seem tame now but even at 50 it hurts like a bastard when you get it wrong. Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 10, 2015 Author Share Posted May 10, 2015 Yeah very true thanks for advice, just wondered if anyone had personal experience in changing sprocket to increase acceleration without compromising reliability too much. Oh and my daily commute home involves quite a few hills. I have got the patients to put up with it, just frustrating getting passed by HGV's! The bike is really good loads of good reviews which persuaded me to go for the YZF. I really want to get through my test as i love biking, given the choice to use car or bike to work I'd choose bike all day long but like I say weather is always a big downside. Link to comment Share on other sites More sharing options...
slice Posted May 10, 2015 Share Posted May 10, 2015 Yeah your in the eye of the storm up there in the land of kilts, there must be a video/review somewhere of what happens when you change the sprocket size, have you tried Youtube? found this tho http://r125forum.com/threads/front-sprocket.1368/ And this http://r125forum.com/threads/front-sprocket.1368/ And another one http://r125trackbike.blogspot.co.uk/2014/08/improving-r125s-acceleration.html Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 10, 2015 Author Share Posted May 10, 2015 Yeah your not kidding there mate hah, i had a read at that topic earlier he appeared to have a tuned bike with quick acceleration, but wanted to reduce it as it seemed to run out of revs in 6th, I get no where near red line in 6th even down hill. Like i say it can sit at 74 n not climb so im lead to believe it is limited (not that im bothered). I'll give youtube a little search aswell but if changing the sprocket means seriously compromise reliability i will give it a miss. Thanks Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 10, 2015 Author Share Posted May 10, 2015 Came across this www.gearingcommander.com it shows ratios and speeds not sure how accurate it is but could act as reference point. Link to comment Share on other sites More sharing options...
slice Posted May 10, 2015 Share Posted May 10, 2015 Ok At least you have something to work with, hope you get it sorted. Just a quick reminder, it's always nice if you do an INTRO in the New Members section, just so folks know your not just here for information and you would like to join in, always nice to have new folks join and contribute. Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 10, 2015 Author Share Posted May 10, 2015 I'll continue to look at pros and cons of sprocket adjustment before i do anything. Thanks for the advice. Sorry yeah I'll post a little introduction. Thanks Link to comment Share on other sites More sharing options...
Volvomeg Posted May 10, 2015 Share Posted May 10, 2015 Had my YBR125 to 75 once and i was absolutely bricking it, it didn't feel safe at all Quiet happy trundling about at 60 until i pass my test and get something that is abit more capable, Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 12, 2015 Author Share Posted May 12, 2015 I've felt like that with a few bikes, I'd just like to have more power low down as opposed to top speed for the sake of head winds and overtaking quicker and safely. Also my 6th gear is useless I thought maybe dropping a tooth on the front will increase performance up to 60 mph. A fee people recommend 13t/48t others say 13t/50t. It will make things less of a hassle when I have to tackle hills etc until I get the time and weather for direct access. Link to comment Share on other sites More sharing options...
Jprimus0910 Posted May 13, 2015 Author Share Posted May 13, 2015 Hi all OK a little update.. I had time to strip my bike a little for a look and it appears my front sprocket had 16 teeth so explains why there's not much get up and go. I bought a 13 tooth sprocket from a 2011 Yamaha YBR 125 as I was struggling to find 1 specific for the YZF but it fits perfect. I Took it out a run and what a difference! Pulls well in every gear. I'm not sure how accurate my speed is now I have 13T/48T setup. I am going to buy a standard 14T sprocket and try that on and update with results. Edit: sprocket that was on my bike was #JTF 417-16 which is from a Kawasaki BN125. Link to comment Share on other sites More sharing options...
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