Fellas, firstly, is there a definitive way of testing to see if the head / base gasket has gone?

I have a very small amount of bubbles coming up when I take the rad cap off. Just don't know if small bubbles and turbulence are normal on a trials bike as all so small.

Secondly, when the bike was on the side stand and ticking over, it jumped into gear ... it did it twice! ... what has cause that?

Bike is a evo 250 2011 and new to me, hence the questions.

Thanks in advance!

Probably got some air in there when you tossed the bike on the ground.

If the head gasket had gone it would pressurise the cooling system and force coolant out of the overflow,,so needing constant topping up.As for jumping into gear,are you sure it was in neutral properly.If it continues to do it,it's strip down time to have a look in the gearbox.Or don,t let it tickover without the clutch in

I wouldn't worry too much about the jumping in to gear. We've all had it happen over the years. Usually just not quite caught neutral properly (especially on a Beta).

Usually if it pops into gear that means it wasn't in the actual neutral in the first place. You can get a false neutral between gears in almost any box. That is because there has to be enough spacing between the gears engaging to prevent more than one from engaging at the same time. Happened to me in a Hyundai once. It was entertaining to the firemen sitting outside the fire station watching me slide by mashed into the steering wheel. I was less entertained. With a trials bike having such close ratios in the first three gears it's easy to think you are in the real neutral. That's why you'll see experienced riders furiously stomping down to first and then clicking up to the gear they want before riding a section.

Most gear boxes are set up with a detented cam attached to the shifter cylinder that controls the position of sliding gears on two gear shafts. There is a spring plunger that sits in the detents that indexes the shift cylinder into the proper position for each gear. Proper neutral has its own detent but when you are in false neutral you are between gear detents and slight movement of the shift cylinder can cause the spring loaded plunger to rotate the shift cylinder into one of the gear detents "popping" the bike into gear. Check out the exploded parts diagrams from the Beta website and look for an access bolt on the engine for the detent plunger spring and then check on your motor to make sure that bolt hasn't backed out. If the bike isn't spontaneously changing gears as well this probably isn't the issue but hey it's not a lot of work to look at a bolt.

Now if the bike was dropped on its shifter or the shifter saw a wonking big hit then the shifter forks that shuffle the gears back and forth can be bent but that usually manifests as difficult shifting and really isn't all that common on a Beta. One thing that is common to Betas is notchy shifting which I attribute to the long aluminum shift lever because it is very flexy. Good thing too as a friend of a friend, who I was assured was an experienced rider, was "test riding" one of my bikes stood on the shifter and jumped. When those of us watching got over the initial shock and asked, "What the *&$# are you doing?" He looked at us with the classic "well DUH" expression and said, "Trying to start it of course."

He didn't buy it. Probably thought it was too hard to start.

Many thanks for taking the time to reply fellas ... I feel a lot better about my "new" bike now!! Regards