In your carb, there is a diaphram which is referred to as an 'acceleration pump'. When you give it more throttle, it momentarily gives your carbureator more gas - to help you get up to the speed you desire. Once it gets up to the speed/rpm you desire, that diaphram relaxes.
It sounds to me like that diaphram (accelleration pump) is not working correctly or is defective. If the carb has not been rebuilt (ever) since 1987 (25 years!!), then it's highly possible that a 'rebuild kit' (which will include the accelleration pump) will take care of the problem for you. You should be able to get a rebuild kit from your Honda dealer. Also, get some good carb cleaner (from an Auto Parts store) to really clean up any carbureator parts that you don't replace (such as the carbureator bowl and body.)
Note: That when you take your carb apart (so that you can put in the rebuild kit), you should take note of how many turns it takes to get each and every screw out with! That way, your settings and adjustments will be pretty darn close for you when you put in the new parts.
Jon: For setting your valves, you will need a 'feeler guage' (also available at an Auto Parts store). They must be set exactly, and you can get the exact measurements from the manual that My5Sons has provided for you above.
Bottom Line: It's time to give your engine a tune up!
USFS Motorized Trail Maintenance Volunteer
Last edited by kentco; 03-05-2012 at 01:12 PM.