Originally Posted by RV12JT
The circlip is not really loose – it is pinched by the screw in the slide from above. The main needle is designed to float which gives the appearance that the circlip is loose. The needle needs to float so it centers itself in the main jet and doesn’t rub on the jet which would cause wear and allow a rich mixture. It’s interesting… the needle centers itself with the ~5 GPH flow of gasoline coming vertically up thru the main jet.
Trust me, they were loose. MWSS is very familiar with ROTAX engines. When we removed the needle we found one clip to be way too loose. This on a relatively new engine, just under 100 hours. The reason for the SB, saw clips fail, and foul the carbs. The replacements were sturdier (Originals Mfgr’d too soft) and you could see the new ones fit snugger than the originals. They still had play, but weren’t wobbling on the needle, as were the originals.