performance carb and reed valve options, head modification questions.


New Member
Feb 26, 2009
Columbia, SC
Well, this is my first post. I've recently assembled an "80cc" kit from bikeberry, it's on a hybrid bike with 26'' MB wheels and slicks. It's not bad, but i'd like more speed and accel. I'll eventually be building a shifter kit (or buying the SBP one) Anywho.

I've been doing tons of reading on here and other sources concerning maximizing 2stroke performance. I''ll be tearing the motor down for some porting and possibly adding some boost ports. I'll also be looking into the best way to raise compression.

With these mods I would assume that the stock carb would be horribly insufficient. So I started digging around on Ebay for some budget options. I assume that the stock carb and or reed valve from a slightly larger engine could work fine. I found a guy selling the carb and reed valve from a 100cc yamaha, and have been considering buying it. here's the link

*edit...can't post links. Ebay item # 220365271090

REED Valve
Ebay item # 220365280193

As for compression, I' know a few honda gurus (cars not bikes) have welded in "quench pads" into the combustion chambers to increase compression and optimize flame travel. OF course the head would probably warp and need to be milled. I don't know if it's a viable option for the ching chong engines but i might look into it.



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New Member
Jun 18, 2008
Lancaster, PA / Newark, DE
do you know the size of the carb? I know many have had success with carbs smaller then 20mm. I was the one to fit a reed valve to my motor but had trouble gettin my walbro carb to tune. I then fitted my stock carb and noticed little gain in power. I then noticed my crankcase oil seals have been leaking so a reed valve would currently be useless until it is repaired (maybe the reason for little power). The intake, exhaust, and transfers (and boost ports in my case) probably can out flow the carb currently fitted. As for bumping compression I know many have sanded the surface between head and cylinder and some have even eliminated their head gaskets to bump compression. As for welding the cyl head, i have not heard of anyone else doing it but I know jim at creative engineering and brains from australia are independently working on new cyl heads.