Budget 70’s frame 48cc

Ordered the Chinese 48cc, it had scratched on cylinder wall and was painted inside the ports & head so they refunded the cost for the kit. After sanding the scratches out of the cylinder wall and picking up a vintage bicycle for $30 she cruises at 25mph and had
 

Attachments

  • IMG_1208.jpeg
    IMG_1208.jpeg
    263.6 KB · Views: 91
I have a stock 05 Yamaha YZ125 expansion chamber & muffler that could be fitted to work. Ordered a G2 reed kit with a better carb and a smaller rear sprocket so brakes will be sorted out and fenders either removed or reinforced. I want to be able to cruise at 40mph using as little fuel as possible and safely as possible while staying under 50cc to be street legal. Would there be anything that would prevent the YZ pipe from working optimally? I know the diameter at the choke point at the end of the expansion chamber should be made smaller for the smaller volume of gas, any ideas about how to do that? Will have pictures showing how I plan to mount it this weekend.
 
Also ordered a 6 pack of base gaskets to lift the ports, anyone have experience with these Chinese 48cc that could give an estimate of how many base gaskets would make it run best with a pipe & reeds. Would cutting a window in the piston help it run better with the mods listed?
 
I have a stock 05 Yamaha YZ125 expansion chamber & muffler that could be fitted to work. Ordered a G2 reed kit with a better carb and a smaller rear sprocket so brakes will be sorted out and fenders either removed or reinforced. I want to be able to cruise at 40mph using as little fuel as possible and safely as possible while staying under 50cc to be street legal. Would there be anything that would prevent the YZ pipe from working optimally? I know the diameter at the choke point at the end of the expansion chamber should be made smaller for the smaller volume of gas, any ideas about how to do that? Will have pictures showing how I plan to mount it this weekend.
You need to check your local legal statutes. In my state Tennessee the legal level ground speed limit is 30 mph. Places like Arizona you're limited to 20 mph. There's several states which allows up to 35 mph.

Bottom line is it won't matter if your build is legal if you're exceeding the speed limit set for these vehicles.
 
You need to check your local legal statutes. In my state Tennessee the legal level ground speed limit is 30 mph. Places like Arizona you're limited to 20 mph. There's several states which allows up to 35 mph.

Bottom line is it won't matter if your build is legal if you're exceeding the speed limit set for these vehicles.
I'm no expert in china dolls but I'm under the impression that the reed valves cannot breathe well enough to run without a windowed piston.
Thanks for the info I will figure out how fast it can go legally! Yeah I figured since they aren’t case reed it would need a window. I plan on watching a YouTube tutorial on how to window them properly tonight while eating dinner! Also ordered this pipe in case the 125 doesn’t work for some reason, can always return it if it works https://a.co/d/ckP0Xsf
Also ordered a CNC thumb throttle since the plastic throttle tube broke, would be easier with the U shaped handlebars to use a thumb than twist at a weird angle. https://a.co/d/3hXJ5Rr
 
Links to Amazon may include affiliate code. If you click on an Amazon link and make a purchase, this forum may earn a small commission.
Match the exhaust and intake ports to pipe and intake runner. Typically the intake and exhaust ports are then chamfered. Should breathe better without touching timing.
 
Back
Top