Riders will now have to pay $8,081 for a certificate of entitlement (COE) before they can buy a motorbike.
The record-high premium - 8 per cent higher than the previous rate - emerged at the latest tender yesterday, along with higher prices for car COEs.
The COE premium for cars up to 1,600cc and 130bhp rose by 1.9 per cent to end at $51,765. The COE premium for cars above 1,600cc or 130bhp inched up by 1.3 per cent to close at $54,000.
The premium for an Open category COE, which can be used for any vehicle type but ends up mostly for bigger cars, finished 2.8 per cent higher at $54,501.
All three new prices are the highest in four months.
Commercial vehicle COE bucked the trend by closing 4 per cent lower at $47,036.
Singapore Motorcycle Trade Association honorary general secretary Norman Lee said the record-high COE for two-wheelers was due partly to buyers downgrading to smaller models after heftier taxes were imposed on bigger motorcycles in February.
By moving from say, a 1,200cc model to an 800cc model, Mr Lee said "they easily save $10,000 right away".
With the savings, they are bidding more aggressively for COEs.
"They don't care how much the COE is, they just want their bike now," Mr Lee noted.
He added that there was "an order for 100 to 120 bikes from a single buyer" in the past week. This could have added upward pressure on COE prices.
The higher taxes for bigger bikes was partly aimed at softening the motorcycle COE premium, which has been rising from below $2,000 in 2013 to breach $6,000 in 2015. It has been hovering around $6,500 in the last 12 months.
But after the higher taxes kicked in last month, it set a record of $7,483 two weeks ago.
Asked what implications the $8,081 premium would have on mass-market buyers, Mr Lee said: "It looks like no one got a better deal."
The COE is now more than double the price of an entry-level bike used by couriers, food delivery companies and menial workers.
Various parliamentarians have in the past voiced concerns about the skyrocketing bike COE and its impact on low-income families.
Mr Sitoh Yih Pin, chairman of the Government Parliamentary Committee for Transport, said the higher taxes were "targeted at reducing demand for larger-capacity motorcycles".
This way, "it was hoped that COE prices will be reduced in order to aid buyers of smaller motorcycles, who use their bikes for essential transport or work".
Mr Sitoh said: "We need to fully understand the reasons for the recent rise in premiums."
Car dealers were not entirely sure what fuelled the rise in car COE premiums.
Mr Ron Lim, general manager of Nissan agent Tan Chong Motor, said the new emission standards kicking in in September and new green incentive scheme starting in January had not caused a rush to showrooms.
"The number of bids was actually lower than the last round," he said. "And sales over the last two weekends had been pretty thin."
Rather, Mr Lim reckoned that the various Japanese sellers having their financial year-end this month might have been a factor.
These companies would want to rake up as many sales as possible before the financial closing, he added.