i purchased a 86 trx 70 for my son. NON running. Engine is in time per flywheel and camshaft marks. i have checked valve clearances to make sure they were not overtight. They are in tolerance. Engine will not crank. Will not hit once on starting fluid either. How much compression should i get, as im checking this next. On/Off switch and neutral safety switch are both ok as well.
86 trx 70 compression
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yes, and replaced the plug w 2 others to be sure. Absolutely will not hit. DOUBLE checked the timing, everything is in time. Compression feels week, as i can turn the flywheel over by hand very easy. I will bring home my adapter tomorrow so i can check the compression. Wasnt sure what these lil trax's should read. Leaning towards a broke ring....
after removing the head and jug, i found that the intake valve isnt seating. Has a bur on the valve face, casuing it to leak. Compression read 45lbs. So thanks for the input guys, should have it running by the weekend. Replacing the rings, and top end gaskets. Valve has been re-faced.
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I know that you have already found the problem, but I want to add something. If you can grab the magneta wheel with your hand and twist it as hard and quick as you can, then turn it loose, it should bounce back when the piston comes up on the compression stroke. If it will bounce back, then the engine has enough compression to run. It might not have the compression it's supposed to have, but it will have enough to run. This is a quick way to check it when you don't have a compression gauge handy.
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