KTM sx125 - water/coolant coming out of exhaust??

[SamKTMsx125]

Hello, I've just bought my first motocross bike (2007 KTM sx125). I haven't even ridden the bike yet and am having issues with water/coolant coming out of the exhaust and gas is getting into my radiator..

My first reaction to this was that the head gasket had gone, so I have replaced the o-rings and base gasket, flushed the engine with 2-stroke (in attempt to remove any water from the bottom of the engine) and put the engine back together.   

The bike kicked up with out any trouble and I let it run for a little while only to find after a few mins water droplets forming at the end of the exhaust... Giving it a few revs, I get a cloud of white smoke and more water at the end of the exhaust. I took of the radiator cap to see a small amount of bubbling. I wasn't sure if it was just due to the bike vibrating on the stand causing small bubbles or gas leaking from the engine but just after cutting the engine 2 big burps of air came up out of the radiator... I don't think this is normal?

I am so frustrated it is unreal! I have just bought this bike, I've not even ridden it and I don't know what to do now? Does anyone think they know what the problem is? or what I should do or try next? any ideas would be greatly appreciated

Thanks in advance

[cnrcpla]

Maybe your cylinder head is warped? This would cause uneven surfaces and no seal. The radiator bubbling is kind of normal, if you flushed the radiator recently (which I'm assuming you did seeing as the top end was off) but shouldn't be doing it excessively. The only other thing that would cause water in the pipe would be literal water sitting in the pipe. It happened to my friend's kx125, somehow, water got in the expansion chamber. When you let the bike run, do you notice the level of coolant in the radiator go down? This would indicate if the water your noticing in the pipe is in fact coming from the radiator, or water elsewhere.

[SamKTMsx125]

Thanks for your response cnrcpla

I have just run the bike again and coolant is now dripping from the frame just like it was before i rebuilt it. I'm pretty sure its not water sitting in the pipe as it would have cleared by now.

When I took the top off everything looked pretty good tbh.. the piston and rings were clean but i did notice some light surface rusting on the conrod indicating that water/coolant had leaked into the engine. I don't think the head is warped but how easy/ possible is it that there is a crack somewhere causing the coolant to leak in and gas to escape do you know??

[cnrcpla]

Anything is possible, but the only way to tell if there is a hairline invisible to the eye crack would be a pressure test. If you know any auto mechanics or have a local shop you could bring it to, they can leak test the entire system. But if coolant is leaking down the frame, can you notice if it is coming out of the overflow hose? If so, that would indicate a definite pressure leak in the engine probably around the head, and if the O rings are new, it would mean the head is warped.

[SamKTMsx125]

The leak is coming from the T-piece i think that connects the left and right radiator to the cylinder. How do I check if my cylinder is warped and how do would i get it sorted?

[cnrcpla]

If it is coming from the T piece I would make sure all of the connections are tight and on correctly. But, to check if the cyl head is warped, take some 400 grit sand paper and put it on a pane of glass or a mirror and sand the bottom of the cyl head gently. If any spots on it end up sanded while others end up untouched, than it is uneven. To correct the problem if it should arise, you would need to get it planned down by a machine shop, or buy a new cyl head.

[SamKTMsx125]

When i got the leak originally (before I changed the gaskets) I tightened the connections to stop it but it came started again out another tube so it is defiantly a pressure leak from the cylinder causing the coolant to leak. What I'm worried about now is that the water inside my engine going to make it rust up and cause morse damage.

I will try the glass paper test tomorrow. thanks for that.

[cnrcpla]

No problem, but it seems likely that the head is warped seeing as it has new gaskets and O rings. It may be salvageable depending on how deeply it is warped. Good luck!

[SachsGS]

Another way to check for head/cylinder warpage is to place a straight edge across the offending surface and use a feeler gauge to measure the actual damage.

I made myself a fixture to mount cylinder heads to my lathe. This way I can use a dial indicator to measure warpage and then machine to repair. I have found heads usually collapse in the exhaust port area, typically about .010 " or so. When this happens the cylinder itself will show telltale signs of leakage across the affected area.  

[Stusmoke]

I'm just going to throw this out there, cos I've done it before: Are all the cylinder head bolts on and are they evenly torqued?