Coolant loss

Hello Michal welcome in, sorry to hear that new purchase is giving you trouble so soon, don't sound good do not use bike until you find where your coolant is going firstly check for any obvious coolant external leaks, check cooling fan operation, drain engine oil and refill to correct level check removed oil to see if you can tell if it is mixed with petrol or oil, normally if anti freeze is being burned from exhaust it has a curry smell about it, if you can remove spark plugs and compare colour around the electrode and let us know findings.

 

doubt that the coolant is going through the gasket, Could be a sheard head stud.
drain the oil to see if it is like drinking chocolate.
Other reason for the rise in level is fuel leak, either carbs or tap. important you turn the tap off when you finish your ride.

 

Yes. The bolt can fracture if poor coolant is in the system and has not been changed. it can look very brown. the coolant is also a corrosion inhibiter. This then eats away the bolt at the bottom then the bolt fractures, as soon as it heats up it forces its way out where the bolt head seats. I have seen this a couple of times. one on a tbird and on a 900 tiger. But it is common on ex speed triple challenge bikes as they were forced to run water only (coolant is slippery and takes longer to dry is spilt on the track).
Not saying this is your problem but a possibility.

If your coolant is ok the a rise in oil level is commonly fuel contamination. smell the oil to check if fuel is in it.

 

Hi there Michal, see comments in red.

 

Hello Michal for guidance only about your concern with your bikes overheating, when taking compression throttle should always open and compression to me compression look good, engine oil condition looks old but looks to me not contaminated with coolant after 3,000 miles would change oil(need to use correct grade oil for motorcycle) and filter again, looks like plugs are a bit on black side with indicating rich mixture,check air filter and replace if dirty( need to be light grey colour) I would try to get plugs cleaned up with a copper wire brush and re gap refit plugs weaken off carbs a tad, the reservoir you are pointing screwdriver blade at I believe is the coolant expansion tank i would fill to minimum mark to monitor over a few days,(after tests coolant should have anti-freeze mix) oil level try to level bike on flat ground and get your oil level correct before running( refer to your hand book) do all levels from cold( leave overnight ) for you to monitor levels need to be correct, when bike is ready to run leave idling and check that cooling fan cuts in an out if it stays in without cutting out check water temperature carefully with hand to engine and radiator if radiator cold engine hot you have coolant flow problem, follow the loose hose back to where it connects the other end looks like a engine breather hose that may connect to air filter housing but not sure.