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mrfartsalot

1985 yamaha moto 4 not starting

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I have a 1985 moto 4 200 the rings aren't all that good and it has a knock but it ran great i left it outside in 20 degree weather for a couple of hours and it fired right up no problem and after a minute of it running it died as if i shut it off as if using the kill switch to kill it but i didn't and it has spark and compression and spraying carb cleaner in the cylinder didn't start it I am out of ideas any ideas of what it is?

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Piston rings and valve adjustment.

Sent from my SM-N920V using Tapatalk

Is it a knock or a tap. If it's a knock. You have to do crank bearings.

Sent from my SM-N920V using Tapatalk

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You may have a drop of water in a fuel line or filter. Open the drain on the carb to see if there is fuel in the float bowl.

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it's a knock and we have been running it all summer with the knock and it doesn't seem to be getting worse lol the rings were ruined by the person we bought it from by trying to go up a steep hill in second going 2 miles and hour. also before we bought it.

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There should be dots on the timing gears to line up with the head. Make sure your at top dead center on the intake stroke with the piston. There should be a mark on the flywheel to line up as well. Take the timing chain adjuster and loosen it so your timing chain jumps teeth on the cams. Then roll your cams to spec.

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What are the marks on the piston.  Did you scrape it like that, is that a crack ? Maybe spray it with starting fluid to clean it up  Did the valve hit the piston ? 

After you clean it up with the starting fluid be sure to spray the cylinder head with WD-40 to lube it back up before you move the piston up and down.   

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