sjhall

I am researching the similaritty of the ttr125 engine with that of the xt125r (also identical to the YBR125 less the fuel injection). The TTr125 has identical specs on paper - 54mm bore & 54mm stroke) and a CR of 10:1 etc etc etc. If this holds tru then there's lots of modification possibilities with aftermarket parts such as big bore kits (170cc) high performance cams and exhaust kits from across the atlantic. Just google "ttr-125 big bore kit" and you'll be amased at what they've done with this engine. I managed to obtain the Service Manual of the ttr and as far as the pages relating to the engine are concerned, both the ttr and ybr appear to be identical. However since the xt and ybr are not sold in the US it will be hard to find anybody on that side of the water to confirm this. ! Likewise I don't know of any ttr125 around me to be able to do a visual check for myself. Any TTR125 owners hearing this ???? we need photos please !

Hi again, Today, I flipped open flip open my Fuel Injected YBR125's seat and tank to expose the totally undocumented ECU. Its an 18 pin unit and appears (from the underside) to be resin filled! I have also (thanks to your contribution) managed to identify the function of most of the 18 pins. One interesting observation is that two of the 18pins (Black/White and Brown) are connected to the 12v supply which may indicate that one of them may be a mode signal used to switch the ecu into an alternate mode (possibly diagnostic or programming mode). Results as follows : Brown - 12Volts Black/White - 12 Volts Black - Ground Red - Magneto Sensor Blue - Throttle Body Sensor Pink/White - Throttle Body Sensor Black/Blue - Throttle Body Sensor Brown/White - Throttle Body Sensor Yellow/Blue - Throttle opening (Variable) Green/Red - Engine Temperature Sensor Yellow/Green - Lean Angle Sensor Orange - Ignition Coil Yellow/Red - Fast Idle Solenoid Orange/Black - Fuel Injector Yellow - Fuel Pump Blue/Yellow - Rev Counter Pulse LightGreen - Engine Diagnostic Indicator (Amber Light on Instrument Panel) White/Black - HeadLight If you like I can send you images of my finds.

This is most welcomed data to the YBR125 EFI community. You may not be aware of how rare this data is. I've been searching all over the net for technical data on the fuel injected model for the past 8 months but all I could find is everything for the carburetted model. Many many thanks. During my research you may wish to know that I have positively identified the same engine (in carburettor form) being used in the Yamaha TT-R125 which is a trail bike modified heavily in the USA. Mods include BigBor Kits (upto 170cc) Carb upgrades, Performance Cam changes to mention a few. 15HP is common place. Our EFI and catalytic based engines only produce just over 10HP whereas the carburetted models are capable of just over 12HP. Even if we manage to achieve the original 12HP the improvement would feel significant. Unfortunatly, I suspect that any mods done to our efi based engines will not yield the desired performance increases unless a method is found to re-map the ecu accordingly. I.E. removing the catalytic converter will probably not produce any additional power and may even reduce it ! I am suspecting that the engine will run much leaner without the CC. Thanks for you contribution.

Increasing the width of the tyre without changing the wheels is apparently a falacy. (so the pro's say) Nevertheless, Michelin make the Pilot Sporty with specific fitment for the YBR125. They are apparently the ones to go for according to many British riders who know wet conditions a lot better than most. However Metzler also do a fitment fot the YBR125 as do also Pirelli. I'm still on the skiddy stock nylons and will be changing to the Michelin Pilot Sporty's as soon as I can convince the local agent to import a set for me. (Not much demand for this size here in Malta !)

Hi Emma, Yes my 2007 model has the side stand. Since August I've experienced 3 issues with my YBR. a) I'm getting a judder in the front when applying the brakes. but it only starts to judder when i hit an uneven surface whilst braking ! I've since had the front springs stiffened to avoid bottoming them out due to my weight. Nevertheless the judder persists. I think it'l be a set of tyres to get rid of those aweful chinese made nylons !. The ignition key appears to have developed a fault such that I have to juggle the key around in the barrel to get it started. Strangely enough, the iginition lights work fine and the starter cranks over - it simply won't fire up ! c) The clutch cable failed and had it replaced with a 2006 model. Fitted perfectly ! I'm now approaching 4K with my YBR and can say that I'm getting a craving for a little something more top-end ! Does the 2006 model have a catalytic converter in the silencer ? I can't wait to get mine off ! Steve

Hi, I recently purchased the 2007 YBR125 and it does have an automatic choke. However it must be said that the 'Automatic' method of choking is not by conventional means ! The 2007 model sports an Electronic Fuel Injection system which controls the fuel mixture and idle speed. I've had the bike for 2 months now and have clocked up nearly 2k without a glitch. Unfortunatly the fuel system is still very new and there's little info about the system on the web as yet. If anyone has any info about the Electronic Fuel Injection System used in the YBR125 2007 model I'd be happy to explore whatever performance options it may present. I use this bike for daily work commuting and found it to be just what I need. Its nice and torquey in the low-mid range but lacks that bit of extra umph top end. I'm sure there's a couple of extra horses in the engine since the exhaust has a built in catalyser which must surely zap some power !