Beta 300rr 2017 Running Lean !!!

[Pandata96]

Hello to everyone, I have big problem which can't solve from long time. My beta is running lean , but the jetting are richer (42 pilot and 175 main 2 3rd clip needle position) I think is may be carb issue and put brand new carb with stock jettin in it (38/168/2 clip position) and now bike happen more leaner. 3 friend betas 300 same year running these stock jettin setting and they're not leanee. I change both left and right crank seal, but nothing's. I replace vforce reeds and intake boot and again nothing is changed. Brand new piston and spark plugs and again nothing. Before all these changes my bike 2 times is blowing out right crank seal out of the case when I give full throttle . And previous owner seizure the bike because is been leaner and change the piston and cylinder and put these bigger jetting to compensate these lean condition. Please help me guys to solve this problem

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[dANbOT]

Hard to say whats going on but, if it was mine...I would do a leak-down test. Only real way to prove engine sealing.
It almost sounds like you have a center case leak. Piston and spark plug sure look like they have been VERY hot.

[Pandata96]

I make pressure leak test at 5psi for 30 minutes and pressure doesn't drop. I spray all potential areas with soapy water

[dANbOT]

Sounds like you got my knowledge covered, hopefully someone else can help!