WA is Australia's hotspot for motorcycle and scooter thefts after a 50 per cent rise last financial year, which has prompted police to offer owners free alarms.
They also urge owners to increase security because thieves often use the vehicles to commit other crimes and evade capture.
It comes as figures show about half of all motorcycle thefts in Australia are in WA.
Police said a 55 per cent rise in motorcycle thefts and 48 per cent jump in scooter thefts was also mainly to blame for driving total WA motor vehicle theft figures up 12.5 per cent in 2012-13.
Bikes were easy to move and many scooters had poor ignition systems and locks that did little to thwart thieves, police said.
Assistant Commissioner Gary Budge said another issue was prolific offenders using scooters to get through small gaps into parks and paths in dead-end streets to try to evade police.
More than 9000 vehicles were stolen in WA last financial year.
The WA vehicle theft rate of 4.18 per 1000 registrations - up from 3.95 the year before - was above the national average of 3.22, National Motor Vehicle Theft Reduction Council statistics showed.
Much of the rise was in motorcycle thefts - up from 331 in 2011-2012 to 513 last year - and in scooters thefts - up from 640 to 945, according to police.
Council executive director Ray Carroll said it was unsure why about half of all motorcycles stolen in Australia were taken in WA. About 60 per cent of the thefts were from homes and about 30 per cent from carparks.
High-performance cars were often stolen by burglars who took the keys but Mr Budge said many two-wheel vehicles were taken from homes without a break-in.
He appealed to owners to use better security, saying alarms, chains and locks were relatively cheap and people needed to take responsibility.As well as handing out alarms provided by the council, police will check more engine and chassis numbers.