JAPAN'S trade reforms are unlikely to significantly reduce its massive trade surplus with Hong Kong, according to trade experts. The Japanese Government has announced a package of measures to slash its contentious surplus with the United States. The package includes attempts to stimulate Japanese domestic demand by a combination of tax cuts and public spending, in addition to enforcing anti-trust laws and deregulation of trade. It will also attempt to ensure open and fair access to four sectors: Government-procured computers, medical equipment, insurance, cars and car parts. Hong Kong Chamber of Commerce economist Ian Perkin said: ''Any opening of the market helps, but I do not think it will do a lot of good for Hong Kong.'' According to the Hong Kong Trade Development Council (TDC), the territory has a $117.7 billion trade deficit with Japan. G K Goh senior economist Ben Kwong said: ''It also seems the Japanese Government is trying to use expansionary measures to stimulate growth which may help to stimulate more imports. But this depends on how effective these measure are in expanding the Japanese economy. TDC assistant chief economist Bob Behull agreed that the short-term impact on Hong Kong's trade surplus was likely to be minimal. He said the market-access measures were likely to be directed at US concerns. These measures would be targeted at areas in which the US had a competitive advantage, such as the car industry and computers. These were areas where Hong Kong did not export. From the Hong Kong perspective, the impact would not be very significant.