47mm BBK Help Please

[jtalk]

Just got a Propel and made the attempt at a 47mm BBK. I'm using stock head, stock carb, stock exhaust, and a filter pod. I should be able to run this by just changing out the jets right? Every jet size I've tried from 32 to 48 does the same thing. I can't keep it running without giving it some gas. Otherwise it dies out.

Is there something i'm missing here?

This is my first attempt at a BBK setup. 

Thank you in advance,

[FrankenMech]

Check out the YouTube vids on how to tune a carb or go back to the stock airbox and try tuning from there.

[jtalk]

That's what I've been trying to do. I've been really successful with stock 50cc's. I didn't think it would be this difficult with a BBK just to get them to stay running.

[FrankenMech]

I like to start out with a 'performance' carb which is already set up for use with a pod filter or no filter rather than try to mod a 'half carb' or 'stock replacement' carb that is made to operate with the other half of the carb being the stock airbox setup. Look around and see if you can find one. You can go up a couple mm in size with a BBK.

Everyone has trouble tuning a stock carb for use without a stock filter setup.

To me the stock carb and filter setup is insane.

[GrumpyUnk]

One thing to remember when you get done and want to run the little beast. The rings are still getting used to the cylinder wall, and WILL produce more heat. They also have more friction. Both of those things will affect how it runs.
I would turn the idle stop screw, on the 'cable' side of the carb, 1/8-1/4 turn CW. That will raise the idle a bit, so be ready to adjust it CCW if needed. I would also think about opening the idle mixture screw on the opposite side perhaps 1/4 turn(CCW). A little bit richer idle when running in new rings & piston won't hurt.
You should only have to worry about pilot and main jets when 'final tuning' for best performance. You should get adequate performance from the stock carb and air cleaner setup. On most air cleaner assemblies there is a small ribbed tube just inside the air inlet at the front of the cleaner cover. It may be removed without consequence(so far). It makes the throttle opening sound a bit throatier. I think, and may allow free air movement.
If you open the idle stop too much, you will be running the engine at idle using the 'middle speed' carb circuits and will get an unstable idle. Be sure the drilled port/jet that feeds the 'byvalve' enrichment mechanism is not clogged. It is built into the float bowl on some versions.
tom