Motorcycle Questions? Ask a Mechanic.
Hi and thank you for your question,
This sounds like a carb issue. Earlier Ventures had a problem with the slides twisting in the diaphragms and creating running problems similar to yours. I suggest pulling the tops off the carbs and inspecting the slides. There are slide lift holes in the bottom of the slide and those, when not in the correct position, create the problem. It is usually not all of them, so you should be able to compare them to each other to determine which is the one with the problem. The solution is to replace the slide. The diaphragm is not available separately.
Let me know what you find. If you aren't sure, take pictures of the bottom of the slides, with all of them in the same shot, and send them to me.
No problem. I hope it helps.