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If you are thinking of selling it PM me I might be interested in it.....

I've run it up to temp In the garage a couple of times tonight and oil seems ok but still boiling in expansion tank. A lot of people on the net say that they boil up due to running lean or something. When I purchased the bike the airbox snorkel had been removed by dealer and there always seems to be a fair amount of water in the airbox when out on the trails. As for stalling in water,that hasn't happened yet touch wood. Coolant level is full in radiator and appears normal, expansion tank returns to normal when cold. Still puzzled

do you mean boiling in expansion tank or bubbling
water will be pushed to the tank as the radiators heat and sucked back as it cools
have you checked the temperature, the stick on strips are quite cheap.
WR usually just re-route breather pipe to air box to prevent water suck up issue

boiling in expansion tank. coolant level in both radiator and expansion tank are normal when cold

Water pump seals...or head gasket...like my dad said.Get your breathers up in the airbox... Check oil every ride.. Let us know...

when i drowned my 690 it took 6 oil changes to get all the water out

Snap on and probably others if you look on net, do a test kit, so you can test a coolant sample and it checks for combustion deposits so you know if head gasket has failed.
Or as suggested tell the dealer you suspect head gasket failure and seek a contribution from Yamaha on such a new bike.
Good luck and I hope you get it sorted

Greetings,

There are a variety of cylinder leak down and cooling system testers on the market, some are quite cheap if you search the internet.

Effectively a cylinder leak down tester uses compressed air fed through two gauges via a flexible pipe through a spark plug hole adaptor, with the cylinder to be tested locked onto the compression stroke t.d.c. compressed air may leak so that it can be heard, seen or smelt at the carburettor indicating inlet valve not seating; the exhaust pipe indicating exhaust valve not seating; the crankcase indicating piston/rings or bore problems; bubbles in the coolant indicating head or head gasket failure; into an adjacent cylinder indicating gasket or head problems.

A cooling system pressure tester is hand pumped via a radiator cap adaptor, any leakage may show around loose hoses; cracks in radiators/pipes; worn seals; or leakage into a cylinder.

Scum in the coolant indicates combustion gas finding its way into the cooling system. Dyes can be added to the coolant or a specialist 'sniffer' tool can test for combustion gas in the coolant whilst the engine is running.

These are tools that all franchised dealers, and the better garages, normally hold and your Yamaha dealer should have them to hand. It generally takes around an hour to an hour and a half to conduct the tests on a motorcycle.

There are loads of past posts and photos on routing carburettor breather pipes, just type the word "breather' into the search box at the top of the forum page. Check out this one as an example; http://www.ktmforum.co.uk/off-road-endu ... pipes.html

If you run a liquid cooled engine without the correct radiator pressure cap then you will see movement of the coolant and possibly even bubbles, this can be natural as the system relies on the cap to pressurise the system to prevent cavitation at the pump,; prevent air bubbles in the system and to increase the temperature at which the coolant will boil. Remember to take care when removing a cap from a warm/hot engine. Some systems allow expansion of fluid to flow into a non pressurised catch tank, that liquid will go back into the system as the engine cools.

Hope these comments and the previous guidance helps. Please let us know how and what you find.

TTFN

Hugh.

Deffo sounds like head gasket to me. Not a massive job if its just the gasket gone. £250ish probably. But the only thing to be wary of is when its stripped down if the piston has been damaged. pitting etc... Or the head is warped...Then you are talking £££'s. If its pressurizing not long after you start it in the expansion bottle that would say to me its the head gasket. Have you run a pressure test on it?

Thanks for all the info. Should be finding out more tomorrow as dealer is back from holiday. Takes about 10 mins to warm up and boil over in the expansion tank, the. Returns to normal when cooled. Some people are telling me this is normal when bike is at stand still but I've never noticed it before as I always warm up bike after every wash down and pre-oil check as per manual. Coolant looks like new and both levels are correct in rad and tank. Just don't know where the water in the engine suddenly appeared from. Oil still looking OK after a couple of warm ups in the garage.
Again thanks for all the replies.
(By the way bike is fuel injected not carb)
Ian