I might not have owned one , but as one of my clubs instructors I've lost count of the number of hours I, and the other instructors, have spent trying to get a consistent run out of these things. Some are good, most are bad.

You have probably dealt with perhaps 10 MDS's in your life . I've had to try and set up at least 30+ or more. Here in the UK these things sold like hot cakes, because they were cheap.

So if you have a good MDS that's great . BUT the fact remains that these engines were not consistant in their manufacturing quality. Why should you have to change O rings in the carb ? The thing should be fit for purpose out of the box. Would you buy a new car and then tear down the engine to get it to run correct.... of course not.

And as for being clueless........... Dave as a fellow member of club Laser , you should know me better than that !