I just bought this bike about 2-3 weeks ago. The owner said it had been garaged for a good year and some time prior to putting it for sale. I've tried riding and all of the sudden when riding it loses gas flow when "dogging" the accelerator, it also happens when trying to push it up hill or a inclined road. It doesn't happen when going downhill. I replaced the spark plugs, took it out for a spin and still did the same. I'm new here and back onto riding motorcycles after almost 15 years of absence. Thanks in advance as to any suggestions about the issue might be.