Im not sure your doing the test properly. The numbers you got were not bad...not great either. 160-180 is what I would be looking for. The way I always did a compression test was...
Warm the engine up completely.
Remove plug and ground the wire
Install compression gauge
Hold throttle wide open
And kick until the gauge stopped rising
Now I have never done a test on trials bike before...just MX bikes, so my numbers may be wrong.