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Hey guys,
I currently have an mc49 m/c with a Walbro sdc carb on it, and I wanted to know if I were to switch to a Tillotson or Mac racing carb, which one could I use, how hard would It be, and what would I need to change?
Below are some photos of the motor/carb setup as it is.
Thanks,
-Adrian

One thing (of several others) is to not over do it with a large bore BDC carburetor, so do not let someone talk you into a McCulloch intake manifold or matching BDC carb. You should stick with either a Tillotson HL size carb with adapter to match vacuum/pulse hole feed, or simply replace the manifold with an all McCulloch manifold and reed set-up and a McCulloch smaller bore flat Back carburetor.

anyone else want to clean up my thoughts here?

Mark Loraine wrote: ↑

Fri Jul 21, 2023 8:26 am

One thing (of several others) is to not over do it with a large bore BDC carburetor, so do not let someone talk you into a McCulloch intake manifold or matching BDC carb. You should stick with either a Tillotson HL size carb with adapter to match vacuum/pulse hole feed, or simply replace the manifold with an all McCulloch manifold and reed set-up and a McCulloch smaller bore flat Back carburetor.

anyone else want to clean up my thoughts here?

Thanks for the advice, I really appreciate it.
couple more questions though:
what are the exact parts I would need to do this conversion? (carb model number, different manifold, adapter, etc..)

this is an M/C style motor, so it wasn't originally made for a kart, so it lacks the special port on the right side of the piston when you take the manifold off, does that affect anything relating to the swap?

Fuel delivery has always been an issue with this motor, as the GK800 I run it on has a seatback tank at the same height as the motor, so it takes a while to get fuel to draw to the carb to get it to start. i understand that these Tillotson carbs have a sort of 'built-in fuel pump', would that solve my issue, or would I still have the same problem, if so, how can I fix it?

If changing to a Tillotson I would even stay on the small side for a 49'er.
You can use a big McCulloch manifold and reed cage with an adaptor plate or you can get a aftermarket GEM style manifold.

If your carb is not pumping fuel make sure everything is clean and right & pulse holes are all clear and not cover3d by a gasket and no leaks.

Rob Voska wrote: ↑

Fri Jul 21, 2023 4:14 pm

If changing to a Tillotson I would even stay on the small side for a 49'er.
You can use a big McCulloch manifold and reed cage with an adaptor plate or you can get a aftermarket GEM style manifold.

If your carb is not pumping fuel make sure everything is clean and right & pulse holes are all clear and not cover3d by a gasket and no leaks.

Rob, what about a WB3A carb off a kt100 Yamaha?

Stay away. Go with a 3/4 to 7/8 bore carb. You only have an 80cc motor.