I tried every effort due to bady 90 engine malfunction but did not improve, I was not repairing and changed the idea in the tuning direction I chose to replace the main jet for the time being. Birdie 90 purchased this product because there is no setting of the oversize OR of the pure jet. It is very expensive to buy one by one, but this item is very valuey with 6 pieces set. I tried 85 sizes first, but my faults were improved with 1 shot ... It was disappointing that I was amazed at what was my hard work. For the time being I wanted to thank for this product, it was a good study.