Hi everyone, I just bought a CBR125R, year 2011 (sold initially in 2015) for rather cheap. I got it Wednesday, and it has 50k km on it. The guy who sold it to me signed a sale contract specifying the engine, gearbox, transmission and all works, with the exception of all the fluids, the chain, etc. In short, that the motorbike was fine, but needed quite some service.

So I got the bike and put it in my garage, and put in a new battery (apparently the old one died - he didn't use it for a full year and left it in the cold - but I personally think it was just flat), and the bike started right up. I gotta change the gas (it's quite old) but it seems to run fine.

Here's the catch tho. I started it, put the first gear on, and tried going forward, and the HUD reported the engine to be overheating. I didn't try anything more than this, since I don't want to take unnecessary risks and kill the engine. I initially thought maybe there was too little oil, or too little coolant. I checked both today, they seem fine (the oil was semi-clear, which I will leave like this until I drive it a little and find out what else is bogus, if anything), even though there was a little too much coolant (slightly over the "max" line).

I cautiously touched the radiator and the engine block right after cutting the power to the machine, and both were cold to the touch. In addition, the fan never turned on; but I don't think it's supposed to, so long as the radiator stays cold. So I suspect the coolant pump is the fault.

Is there anything I missed? How to test if the pump works?

Cheers.

 

How long had the engine been running? I would be more inclined to think that the CTS might be malfunctioning. I don't have documentation for the CBR125 as they are not sold in the US.

 

About one minute, give or take. I did it two times on two different days, the HUD had the rightmost bar on the heat gauge blinking after I got the bike revving a bit. I didn't go high tho, like 5 or 6k rpm tops for a couple seconds.

Another important bit of information is that when I put the first gear, I didn't rev the bike much (maybe about 3k RPM) and started releasing the clutch, it struggled moving. I don't know if 3k RPM is enough torque with this bike to get it moving; considering it's also possibly jammed a bit from stationing this long. I'm used to doing this on some 600cc or so, and that works, but I don't know about such a small engine. I'd appreciate if anyone could shed some light on that, too. Thanks!

Edit: so I did some youtube watching, and apparently, the heat gauge starts without any bar on. From what I remember, even before starting the engine, the display reports some heat (about half). This would indeed hint at a CTS fault indeed. I will check that tomorrow. Thanks for the tip!

Edit 2: Apparently, it can also be a wiring problem. I will also check that too. Will report tomorrow if the HUD reports some temperature before the engine starts, and will also check the wiring.

 

So, user "IDoDirt" was correct. The fault is in the CTS. The sensor reports any temperature to be over 60-70C. And it goes very quickly up from there. So, I will check the cables, see if the voltage's correct; and if it is, order a new CTS.

Now, I drove the bike for a few meters, it goes just fine; with the exception of the bike accelerating every time I turn right. That's not a mechanical problem though, it has to do with the acceleration cable itself.

So, I guess the thread is solved. Thank you!

 

Glad you got it sorted out.

 

Great result, well done