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I've been getting different information on valve settings and finding the .003 and .004 are not quite enough on these engines. The aluminum heats up and expands sometimes causing valves to be partially open resulting in lost compression as the engine heats up. I've found through trial and error that .006 to .010 are a more reliable setting and allows for expansion. These are with the BBK on three bikes now. Not a ton of experience here so this is only my findings so far. We plan on building several more as the days pass, sort of a hobby thing. Constantly tuning and comparing and asking around this is where we are at. One of the 50's we've taken apart had around a .020 setting and it ran fine? I don't want to confuse, just telling other's what we found.

Hey all, reading through this thread I would like to add something about the carb on these things. I am an older motor head but never worked on these things till recently. Learning quickly as I was lucky enough to talk to a tech that knows them pretty well. Here's the thing I learned with the carb when I was having a problem similar to yours. I was asked, did you prime the carb? I said yes of course but I was doing it wrong. In priming, one of the most important things is after you get it running it must be primed by holding your hand over the intake of the carb and reving engine hard. It wants to stall and it may. Restart and do it again and again until you get a handful of gas then, do it again. The way it was explained to me is that there is so many small passages in the carb it's impossible that the air will work out. This is the only way to prime and I can you this, it worked for me after I was shown how to do it. I did with the new superflow carb and my problems were gone. The thing never did run right when I bought it....through the old carb back in and primed it the way it's suppose to be and bingo....even that old carb worked well. So I guess what I'm saying is that you are right in it being a carb problem but prime it hard and hopefully it will eliminate your carb problems. I guess a lot of you know this but I haven't seen it mentioned so I figured I would add my .02. Hope it helps cause carb problems are frustrating. The old days we used to adjust the float with a little square they gave you and it had to be dead on. Accelerator pump had to work correctly like in these things which can be checked with the carb in your hand, loaded with gas, it should squirt through the jet. Again, I was shown this otherwise I would never know...

Okay, that all makes sense. Just one other question, I noticed they have a A9 performance camshaft available. Is this worth it? It says it will improve performance on a 50cc BBK. What do you guys think about that?