There is nothing wrong with the exhaust, that's the exspansion chamber, need a good one to run right. The dirt bikes is probably heavier, so less power to the ground. Try online at PBParts in Florida, they have parts for both your bikes.
no prob with the age i got into these when i was 30 lol i have had big bikes dirt bikes quads ect my whole life thoG-day. I might be a little older to be just starting out with these, but whatever. Anyways, i picked up a couple bikes a while back for cheap, and have been lurking around hear for a while picking up some of the lingo before i posted. The first one i got was the dirtbike. My boys (1 and 2 years old) love it, it has just enough power to tow me with one of them between my legs. The other is a cag crotch rocket. It has the zh-1 jug which I believe has bigger ports. I was surprised when I got it, what a difference in power compared to the dirtbike. Two questions I did have are for parts I can't seem to find. One, can you get lower gears for the dirtbike chaincases? I don't need any top end on it really, a little more takeoff would be nice. The second question is about the pipe. I know just enough about two strokes to know that the bubble thing on there isn't doing squat. Does anyone make a performance pipe for these?