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1987 XR200 Timing chain change


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Take a look at the sprockets anyway. There's a good chance they're in good enough shape to keep.

You have to pull the flywheel off, but it's actually quite easy. You need the right size bolt that threads into the center of the flywheel and it pops right off. I've heard it said that the rear axle has the proper thread to do the job, but you can get the right size bolt from Ace Hardware.

- Brad

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Never changed a crank sprocket so I'm curious how to do that.

Chuck it is relatively easy. I have a power steering pulley puller that pulls the sprocket right off the crank. To press it back on I use a hardened stud that threads into the crank and on the other end I used a hardened nut and some spacers to "press" it on. Now for the helpful hints: I use a die grinder and carbide bit to grind off some of the inside of the old sprocket once removed so it slips easily on and off the crank to use as a spacer to press the new one on. There is no keyway for the sprocket so you have to align one tooth with the flywheel keyway for timing. (I think it was the flywheel keyway...take a good look to see how the old one is aligned before pulling it off...I am working from memory here) You also have to try to predict how much the sprocket will turn as you press it on since you aren't using an actual press..as you turn the nut it will spin some as you press but not much. Using the stud as a press its pretty hard on the threads in both the crank and the stud as you might expect....so I get eveything ready to go and put the new sprocket in a 400 degree oven for about an hour then press it on as fast as I can before it cools...it goes on relatively easily warm. I have done this to 3 different 200's now with good results. The first one I did I had to pull the sprocket back off and do it again because I didn't realize about the spin pressing it on... I was able to pull it back off, warm it and press it back on without problem. I also use a small 3/8 impact gun set at a low setting to press it on instead of by hand to keep the engine from spinning over. I think it is easy enough to do and the sprocket is cheap enough that it isn't worth not doing if you are putting on a new chain. On the ones I've done the bottom sprocket has always been pretty worn...the top sprocket usually doesn't look bad but again cheap enough and easy enough to do.

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