Has anyone had problems with water getting into the oil on a 300 gasgas, Iv'e put 3 seals a new shaft, new shims, everthing but the body! Kev at gasgas looked at it, fitted new seals and impeller again, was ok for a day. Kev did say he thought the the mains were on the way out, so I did them. Iv'e had the bike just over a year it's a 04, it had had a hard life so I had to do a fair bit of work to it then, including a water pump seal, it has been ok untill now! I don't know a lot about trials, I only got into this as my 12 year old got interested, he has a 125 Beta, Iv'e done more road racing, we have a lot of fun, do a few trials, but Im loseing intrest, both bikes give so much trouble, do I need a Scorpa or montesa (Jap engine) to be able to just come home wash them off, bit of a grease and oil up and look forward to next time?

Sorry to hear about your difficulties. Are you actually losing coolant? I've found that my gearbox oil will go milky sometimes but the coolant level is okay and I wonder if its just down to condensation or water getting in via the breather. Once the oil has gone milky its difficult to get all of it out and it can take several changes to get it clean again.

The bikes will give trouble if they have had a hard time as would anything. In practist a trials bike if cared for will be reliable as its not worked in general to hard on the engine.

Forget Scorpa as they are very weak in my opinion, stick to GasGas or Beta but a decent one.

Never heard of it on a GasGas but Beta did have issues with the case on the water pump side failing after 2-3 years.

Chin up and good luck

Yes the water goes, i only have to run it till the fan starts in the workshop then next morning start it, its milky, I would like to borow another pump to try (worth a try) but I live near Dover so its not a really big trials area, so not many people around here to ask. Thanks for your help, its nice, all Ive had around here is "your wasting your time, if a trial bike is over 3 months old, scrap it" surely thats just rubbish.

i have cracked a few clutch covers on my 300 first sign is water getting into the oil then losing oil then kick start plays up. i cant see it being this especially as factory kev has Had a look but worth a checking i suppose. and 3 month then scrap it load of toss all depends on how its been looked after.

make sure you get the the rite seal for the water pump it should be a double lip seal, have done gas gas with that problem,people have been put single lip seals in, either lets water into the gearbox or oil into the water.

When you did the main bearings did you take the head off the barrel? I know there's no need to, but I wondered about the condition of the rubber 'O' rings. If they're on their way out the cooling system can be pressurised by leaking compression and make the pump leak. The bike will usually spit coolant from the overflow too, if run long or hard enough.

Thanks everyone, When I did the mains I stripped the engine fitted new O rings in the head, new crank seals, new small end. All the pump seals etc came from Shirts (when Kev did them, FOC, which was nice) these engines are so simple, Im a machanic by trade so I don't think Ive made any silly mistakes. I dont know what to try next!

Get the bike hot and pull the waterpump out from the clutch case so you can see where the water is coming from? Maybe you've got a pin hole or a porous casting?

Done that, it doesn't leak then, I have had it going tonight, at the moment all is well, but it's done this before! It seems better if you only nip the allen screws up, don't tighten them, I think the pump shaft maybe slightly over long! when I got it from Shirts I pointed out it had a different finish, they said that was because it was made by a different manifacture, I assume they ment for gasgas, not a pattern part, If this work's Ill shim it out a bit on the three screws.