I have just had to replace the fuel pump on my 09 XTR..
Might be worth checking it...

but it dose sound like it's prob spark...

If it is the pump theres a cheaper option than Yamaha offers
by replacemant of the whole pump unit....
like $800 cheaper...

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Harley Davidson..
The easyest way to turn gasoline into noise with out the side efect of horse power...