Newbee With a Grubee in MT

[www.cowboy]

Hey from Montana. Got my kit (48cc grubee) put together on a Trek 800 mountain bike. Got a 2 questions.
1. Has any one tried a KMC z510hx bmx chain? It is rated at 2600 lbs tensile strength.
2. From 1/4 throttle to almost wot the engine four strokes. I junked the cns carb and replaced it with a speed carb. I have close to 50 miles on it. The c clip is in the middle of the needle valve. I was going to do a plug chop last time i rode it but the chain decided to chop (oem chain broke). Howerver, I did pull the plug and it is a nice brown color. The engine runs good at wot. Could the four stroking be caused by a weak spark and not a miss adjusted carb?

 

[ducedave]

Hay Cowboy I don't know about that chain-A #41 will work stock is a #415
4 stroking is most often to much gas move the clip if that doesn't work you may have to rejet---maybe let it break in some by before all that as your oil mix for the first few tanks should be more then you would use after the rings and piston seat.
I went with 16/1 then 32/1 and now I use 40/1 and my carb works differently at these mixtures

 

[www.cowboy]

Thanks for the reply. Just 'upgraded' to some mini ape hangers from my kid's old bicycle while I am waiting to get a new chain.