Yikes. Loosing a lot of water......

[Josh|RD125LC]

Took the RD out on its first run since the new crank etc, topped everything up, went about 15 miles, came back, checked the radiator and coolant bottle, and both were near enough empty! It did get very hot at one stage, had to pull over and let it cool. Held my hand over the exhaust, let some fumes hit it, pulled it away, and I had water on my hand.

Now I checked all the hoses and connections, and they are all fine, no visible leaks. I can't really think what else it could be. There is a possibility that the head could be cracked, but I hope that isn't the case.

Any ideas?
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
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[lilredmachine]

head cracked or head gasket gone

I'm afraid those are the two options in this case. Check your oil for traces of white foam/scum, a sure sign that oil and water are mixing.

Edit: if it did get v.hot, it could have damaged the head gasket then, whilst you were riding it. Only problem is that if it did, it means the water is getting out/in via somewhere else.
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Bikes: too many, too much for one man to maintain anyway.

[stinkwheel]

Sounds like the head gasket is dead. Feel the radiator hoses after running it for a bit. If they are rock hard, this is your problem.

Head gasket would be my first port of call anyway on an LC 2-stroke. Not all that big a job. Check the head isn't warped before you fit a new one by putting it on a sheet of glass, it shouldn't rock about.

It can often be a very small 'jet' of gas escaping past the gasket into the water jacket causing these symptoms so inspect the gasket surfaces closely when you take the head off. If you see it, you know this was the problem. If there is no sign of a leak, the problem might be elsewhere.

Could also be caused by a knackered radiator cap.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[the grim reaper]

Before you do all this though, check that your radiator hoses aren't leaking at all. The water in your exhaust is possibly the normal amount but, if it is actually chucking out water, then I would also vote for head gasket.

Cheers

Grim
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Adverts don't always work: Remember that advert, where the army are running across the desert and they have a wounded man on a stretcher. They get to a ravine, the bridge is down and a caption pops up that says, 'What are you thinking?'. I don't know about you but I was thinking, 'Christ, I'm glad I'm not in the f***ing army'.

[Barry_M2]

[Josh|RD125LC]

[Josh|RD125LC]

Just taken the head off, and I can honestly say I didn't struggle one bit loosening the head bolts, two came off with ease, so Im guessing that was the problem. Head gasket is dead, split in 3 so need a new one again. But I screwed up a bit. I forgot to drain the water before I took the head off, so I hope to god that little or no water got in the crank casing.
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
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[Barry_M2]

There you go, thats the problem. Most of the water would have gone out through the exhaust ports, the rings would have stopped most, if not all of it getting to the crank.

Sounds like an easy fix.

[Josh|RD125LC]

Head is fine, not warped and no cracks. Think I may have to take the barrell off and check for water in the crank casing, if there is any then I'm going to need to soak it up. But the piston was near the top when I took the head off, so I doubt much water will have got past the piston?
____________________
Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
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[Josh|RD125LC]

Hmm we have the same problem again. Fitted brand new head gasket again, and this time torqued up the head bolts to what it says in the haynes manual. Topped up with water, and started it up. Same happened again, had water seeping through where the head meets the barrell. So off comes the head again. Close inspection sees that the head is in fact warped, so I get cracking with skimming it on sheet of glass with wet and dry paper, rotating it around and around in a circular motion. When all I saw was a shiney surface all round, I stopped. Got the old man out, he put silicon sealant on the gasket, put it on, and on goes the head as well. Top up the water yet again and start it up again. Tick over was fine, kept steady all the way, held hand over exhaust and it was just throwing out very fine dots of water, which I presume is whats left in the expansion chamber. So we leave it ticking over for 2 mins or so. Check the water level and its barely gone down, about a mm or two. Look down at the barrel and head, and what do we see, water seeping through again! At this point me and my dad are both baffled, and haven't a clue whats happening. Dad says that it must be the head, been skimmed to many times or something.

What do you think?
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
RD125LC Pictures

[stinkwheel]

Did you do the gasket surface of the barrel as well?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Josh|RD125LC]

I gave it a quick going over with the wet and dry, was quite awkward to do so I didn't do it for long, just got all the crap off the surface.
____________________
Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
RD125LC Pictures

[stinkwheel]

I was just wondering if that gasket surface is a bit deformed/marked too. Might be worth giving it the glass plate treatment too?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[cagiva gezzer]

I used valve grinding paste and lapped the head and barrel against each other.

It's also a good way to tell where they are not meeting each other due to high/low points.
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"because one stroke isnt enough and four strokes waste two"

[satans_BIG_helper]

[Josh|RD125LC]

Yeah I may just get another head from somewhere.

My dad was going to use the grinding paste method, but didn't have any left.

I just don't know what to do, whether to give the top of the barrell gasket surface a quick sand, or just find another head from somewhere.
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
RD125LC Pictures

[Josh|RD125LC]

Also forgot to mention, the past 3 days I have taken it out of the shed after being left in there overnight, I looked down at the carb, and have seen a large clump of ice at the end of the drain hose of the carb, happened 3 days in a row. Any idea whats causing that, and its iced up petrol obviously.
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
RD125LC Pictures

[satans_BIG_helper]

do you turn the petrol tap off at night ? if not i would do so as its probably just where the bike is on a slope being parked on a side stand its running out the overflow ?

[cagiva gezzer]

[Josh|RD125LC]

I'm in Plymouth, and it hasn't really been that cold lately. Better turn the fuel tap off then. Just has never happened before. Strange.
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Honda MBX50 | Yamaha RD125LC | Suzuki RG125F Lucky Strike | Suzuki GSF600S
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