How do you adjust the carb on a HHM80. I just purchased this motor on a bulldog 3 wheeler and the guy had put a new carb. on it, but he said he couldn't get it running for more than about 30 sec. I brought it home and removed fuel bowl and cleaned all the slime etc. out of it. The gas tank was also full of nasties. With new fuel and everything cleaned up it started but ran like crap. I removed the black plastic cap off adjuster and screwed in till seated then backed it off about a full turn before it idled right. I put cap back on and still runs a little rough. Are there any other adjustments besides that and making sure the jet in the bottom of the fuel bowl is clean?