Hey guys,

My new bike has a very very slow coolant leak. Doesn't steam or anything when riding, just drips every once in a while when parked. Radiator hasn't even needed topping up. Yesterday a buddy and I pulled the fairings off and tried to source the leak and after some head scratching couldn't figure it out.

The coolant is pooling around the base of this (red circle), not sure what it is - coolant temperature sensor? We thought it could be but couldn't figure out why it would be screwed into the block instead of the thermostat housing or something like the fan switch.



Temperatures have been absolutely perfect until today on the ride home from work. 45 minuets in and the gauge started reading a bit odd - would drop low, or wave up high when stopped then when getting going again would read what I would say is accurately. My mind immediately jumped to the obvious conclusion - enough coolant has leaked for an air bubble to form in the system. I attempted to bleed it tonight however and the radiator is completely full - couldn't put in a drop.

Any thoughts? Bit confused on this one.

Cheers.

-A

Have you checked the chrome coolant transfer pipe in that area it has rubber seals on the flanges and one on the pipe each end ?

That is the oil pressure light switch you have circled.so will be oil if any leaks from there.try checking what dave has said.the coolent pipes in V of motor.

Ah, that makes sense. We didn't think it would be a coolant sensor.

With the driver's side fender off I got inside the V with my borescope and dug all about. Couldn't find a thing. I didn't spot a chrome coolant pipe though.

The only hose that wasn't very recently replaced by the previous owner is the one coming off of the thermostat housing pointing towards the tail. It is right above the wet area so an obvious culprit, but after going over it with a fine tooth comb including scoping the hidden far end I couldn't see anything wrong.

On your picture just to the back of where you've circled there is an alloy housiing from which a transfer pipe runs across to another housing on left side if OK then leak may as you say be running down from the small hose that connects stat to rear cylinders its awkward to get at maybe hose clips might be loose.

you can see the chrome transfer pipe in the middle of the V in the above picture, it is secured by a cap each end which has a gasket on it, the pipe itself has an o-ring each end too.

I had an issue with a pinhole in the pipe and was spraying a fine mist underpressure which was enough to collect in the engine, made a new one out of some old pipe as its discontinued part.

also had a different engine but same pipe have a leaky o-ring.

its defainly coolant and not fuel from the carbs? since the thermohousing and what not is above it could be dripping down too. im sure youll find it.

DSS seem to imply from their listing that they can source unbranded ones, yet describe them as OE, which I find curious. I got a transfer pipe from CMS a couple of years ago, complete with the inflation busting Honda parts label on it....

Thanks for the extra info. I'll have to dig around when I have the chance. If it's got a hole I can weld it up no problem.

Some more info on the temperature gauge thing - I've been keeping an eye on it on the last few days and it seems to read differently depending on the engine RPM. Now I don't mean it heaps up faster when I thrash it (duh), more that when I'm in motion, or revving when stationary it jumps up (almost as fast as the rev's) about 2-3mm to where I would say is accurate. When idling, it still reads but the needle drops down 2-3mm.

I tried a bleed and there don't seem to be any air bubbles. This to me sounds like an unrelated charging issue. I did a voltage check with a multimeter and got a constant voltage of just over 12 for 60 seconds or so after a cold start. It slowly climbed to about 12.3 volts, at which point I had to call it and start riding (out wayyyy too late with work the next day).

My background in cars leads me to think this is way too low and the generator has partially failed. I have heard that the electrical systems on these bikes is pretty crap though. Is this normal? The bike is starting and performing as per normal.

This just started last week. The preceding weekend I fitted a HID kit, which I immediately removed due to a faulty ballast. If I still had it fitted I'd guess it was drawing too much power (ordered a 35w kit for this reason) but seeing as it's not, is it possible I freaked something out during the install? I can't imagine what but it pays to ask.