Don't know anything about the "power jet controller". There's loads on this forum about helping to sort out the lumpy bottom end on Vees. So suggest you have a rummage. One solution is to fit a Power Commander and re-map the low end fuelling. This can be quite expensive to buy, install and set up correctly. Another is to get the fuelling re-mapped using a "Yoshi" box at a Suzuki dealer if you can find one that still has one. Fitting a Timing Retard Eliminator (TRE), which can be picked up for under £15 if you shop about, may well help a bit. First thing is to get the bike properly serviced and start from there.