Tubes underneath bike? MK2

[sbc]

Hi there,

I noticed there was a very small patch of 2 stroke oil under the bike so thought I'd better work out where it's coming from.

Okay so I have 3 tubes. Tube A is the carb tube, but what are tube's B and C for? I tried to follow them but would probably need to remove the tank to really work it all out.

Any idea why tube C might be dripping 2 stroke oil? I haven't worked out whether the oil was from the inside of the tube, or whether the oil was following the outside of the tube, if you know what I mean.

It's not fresh oil, it's dirty. Is this unusual?

https://www.anonimg.com/img/c51ffa3badf ... c3e34e.jpg

[knackeredMk1]

A and B are probably carb drain tubes. C could be from the crank breather tube that goes into the crank case slightly forward and under the carb. If the dripping oil is 2 stroke then you have a leak in the 2 stroke oil system - most probably from the oil level sensor. The oil is seeping out and running down the frame/reservoir to collect on the bottom rails before dripping on the floor. To stop this leak you need to drain down the oil to below the sensor and then thoroughly clean the sensor and the surrounding reservoir with contact cleaner. Then apply a good silicone sealant to the sensor before refitting it. It could also be a leaking hose or connection.

Worst of all it could be the seal between the oil pump and the crank case leaking allowing oil to flow into the crank case and out of the crank breather tube. This is much less likely though.

[sbc]

Such a detailed reply, thank you. In my experience these things tend to get much worse over time if left, so although not a huge issue now I need to get this sorted.

Thinking about what I've seen, it's the outside of the tube which appears wet rather than the inside so I suspect it's as you suggest, dripping down from the frame on to the tube itself.

I will take the fuel tank off tomorrow night to see if I can get a better view of what's going on. If I can't figure it out on my own then fortunately I'm taking the bike to my dads in a couple of weeks and we'll be able to fault find a lot more easily in his garage.

[knackeredMk1]

Thank you.

If it isn't 2 stroke oil and it is coming out of the crank breather tube then it's most likely to be an overfilled gearbox or the main crank seals have gone and are letting pressure out of the cylinder into the gearbox.

If the oil is not 2 stroke and is not coming out of the crank breather pipe then you have a leak from the gearbox. You can track this down by cleaning the engine thoroughly and looking for an oil trail.

[sbc]

Okay I had a chance this evening to do some more investigation. It's fresh oil alright, from the gearbox! I know because the gearbox oil is red and my 2 stroke oil is blue.

Despite an examination lasting about 15 minutes, I could not find where it had come from. It's definitely NOT coming from inside of tube C, it just happened to drip down the outside of it.

What I did though is clean up the area and then took her for quite a good ride to try and see if I could find the source. This time though I could not find even one drop! I can't explain how one moment I'm wiping it from the frame and the next there's none, unless the previous owner overfilled the gearbox oil and now it's seeped the excess out?

I will continue monitoring.

[sbc]

Just couldn't resist going out to the garage for a quick check now it's had a chance to cool down.

Gearbox oil is weeping where the gear select meets the engine.

Have ordered a new seal which looks easy enough to replace once the oil's drained out!