I'll post the gory details of my fix under the topic I started. basically, buddy brought this to me AFTER he tried spraying cleaner inside carb. he re-assembled the jet needle assembly wrong. one of the plastic spacers was out of sequence and subsequently got caught up inside the piston valve/diaphram. Hard to believe something so simple can cause so much aggravation, and HOURS of troubleshooting. And Yamaha manual for the wolverine shows 2 different carb diagrams (without telling you that). subtle differences, but they are there if you look closely, especially the jet needle configuration.