Re: 1989 Invador
Good deal, I had to ask to make sure because your question about the accelerator pump threw me off a bit.
Like the others I would suspect choke setting or accelerator pump issues. The accelerator pump is inside the carb, it sprays a bit of raw fuel down the throat each time the throttle is opened. Changing the choke setting can be done with the carb on the engine. Accelerator pump isses require a rebuild in almost all cases.
Some of this is easy to check. If the terms below are not familiar to you then I suggest finding someone familiar with carbs to help you with this.
With the engine not running....
Choke Check:
When it is cold take off the flame arrestor (air cleaner) and look at the top of the carb. The choke plate should be closed or trying to close. Move the throttle forward about half way and let it return. The choke plate should close all the way then. If it does then the setting is probably close enough. If it does not move then the setting probably needs to be changed to the "rich" side. This could also be due to a linkage problem.
Accelerator pump squirt check:
Hold open the choke plate and move the throttle forward again. As you do this look into the carb. The fuel should be spraying in, you should be able to hear it as well as see it. If not then the accelerator pump circuit or mechanism inside the carb needs work and it is time for a carb rebuild.