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Yamaha 74 DT 175 low compression


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A friend gave me a Yamaha 74 DT 175 that had been stored in a barn for a long time. I cleaned the gunk off and checked the tank and it was quite clean. I replaced the spark plug and it had almost no spark. I pulled the flywheel and cleaned the magneto and all of the elements of the stator plate (It looked like water might have seeped in through a small crack where the wire bundle leaves the magneto cover.) I cleaned the point and re set them. I finally got decent spark, but no fire. With a little instant start I could barely get a burp out of it. I pulled the carb and gave it a thorough cleaning (It was also surprising clean). Still no fire. I checked the compression and it registers a consistent 70.

So where do I go from here on my restoration venture? (Note to self - check compression first.) JW896

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i have a 78 dt 125 and it had very little compression,and little power. so i decided to rebuilt it. i had it bored .40 over, ported, put a new wiseco top end in it, and put in some boyesen power reeds in it. when it was all done, it really didn't make that much of an improvement. i was very dissapointed actually. and it still had the same amount of compressin. so i doubt compression is your issue. i would check things like the coil (went out on my old girl) connections, reeds................

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