250-500cc Bad vibrations and cylinder crack

Hi Guys,
I have recently purchased a 09' WR 300, it is a big change from my last ride a KTM 540 exc but heaps cheaper to register in Australia as it is less than 301cc, anyway I'm having trouble coming to terms with the amount of vibration in the frame, I've checked all mount bolts, main bearings, filled handle bars with urathane and checked bar isolating rubbers- all ok
Is there anything else to check or is this normal for a 2 stroke?

Also I have removed the head to adjust the PV and identified a small crack between the large and small exhaust port, can this be repaired with a sleeve and are there big bore kits avaliable to increase bottom end?

You can have it welded and re plated. No sleeves on the newer huskys they use a nikasil plating.

As for vibration not too sure. The 300 will definitely vibrate more than your ktm 4 stroke though.

my 2012 wr300 cracked the barrel between exhaust & sub port.the dealer admitted this problem only happens on the 300.3 successful warranty claims 4 top end failures & one 4 stator failure ,all with less than 700km & it is still not fixed.put a 250 barrel on or sell it