Thanks mateThere is a screw holding the baffle in, accessible through a hole on the lower inside rear of the muffler. Remove the screw and use a slide hammer with a hook to pull the baffle out. Clean off all the carbon and rewrap the perforated tube at the rear with packing material.
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The 250 runs, has developed an intermittent spark issue on the left cylinder. most engine parts are readily available and pretty cheap. The 200 needs a bit more love, but hopefully she’ll be up and running in a month or two. She needs a side cover and oil tank, paint, decals and gauge faces which are proving to be a little more difficult and expensive to get.A 1977 Yamaha RD 250 was my first bike! (bought used in 1984).
I had no riding experience other than a few laps inside a parking garage on a 4-stroke cruiser. Went to check out this bike, never having ridden a 2-stroke. On the test "ride" (you'll see why that's in quotes), I carefully let out the clutch, the engine rpms ZOOMED up, I panicked, let the clutch out and wheelied the bike across the street, dumping it the neighbors driveway. OOPS! You bet the seller made me buy it (and I quickly discovered salvage yards for used parts, some cheap tools, and how to work on a bike). Fortunately, she and her friend were roadracers (she must have been one of the first women in modern times to have been a racer), spent some time with me showing me how to ride (literally, spent a good hour with me) and teaching me the necessity of wearing safety gear (good on them for both of those things, I'm an ATGATT rider!).
Great find for you, I hope it doesn't take too much getting it into running condition. It looks great in that photo.
I'm still hoping to get a 1985 RZ350 in the Kenny Roberts/Yamaha "bumble-bee" paint scheme (my first dream bike). Unfortunately, they're pricey today and unless they've been maintained over the last nearly 40 years, all the rubber and plastic is probably in rough condition.