Hi everyone I'm matt, I wondering if anyone can help me with my issue as I have little experience, basically I have had my engine rebored I've put it all back together (all Yamaha genuine parts) and it started first time then after five mins of it ticking over I have reved it up a little and coolant started gushing out of my exhaust can any body help? Many thanks matt [emoji2]

And forgot to mention its a DT re 125

yo sure its not condensation matt? 5 mins and this damp weather would be about right for it

I don't think so as it was quite literally gushing out of back box and; only put it all back together last night

you must have one heck of a leak from your head gasket then?

Yep or a warped head

There is a tiny leak coming from the warmer pipe from the carb to the top of the head dripping from a little screw next to the thermostat but wen it was running I couldn't c any water leaking from the head gasket #pain in the ass

no you wont see it, it may be leaking into the cylinder bore!

did you make sure both gasket faces were nice and clean before re-assembly?

did you fit a genuine yamaha head gasket?

did you fit the gasket the right way up...see the 'UP' tab

is there any possibility the head is warped?

did you torque down all the head securing bolts?

questions must be answered here I think

Gasket was nice and clean both sides, went from the packet straight to the barrel yes was genuine Yamaha head gasket, the gasket was fitted correctly however I didn't use a torque rench

Did the bike blow up and thats why you bored it? If so you need to check the head for warpage set it on a glass plate and check with feeler gauges and check for scratches in the sealing area on both the head and barrel.

If you can get a cooling system pressure tester pull the exhaust pipe off and lower the piston past the export and pump up the pressure you will see coolant comming out the exhaust if the head is the problem.

Have you checked the coolant level ? with this amount of water ,shurely you would have hydrolic lock, is wasn't just old liquid coming out, has it stopped thowing it out ?

I cut the bike out soon as it did as I was worried of causing more damage, and it was rebored due to the piston skirt breaking

Also the coolant in rad is full and so is the water tank which is y I'm lost on how it has done, this

could it be that way back...the piston broke because the crankcase was half full of coolant and you just fixed the symptom (broken piston) and not the cause (coolant in casing).......so now you are just seeing the coolent being chucked out the exhaust??????