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Idles great, mid range, full throttle fine. At 1300-1500....6mph speed sounds like running on 5 cylinders and shakes. Compression 115-120 all. Carbs cleaned no difference. New plugs same.
Any ideas?
Any ideas?
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if you are losing a cylinder at that RPM, but idles fine and runs fine at high RPM,
I would think you have an off idle port in a carb with a problem.
I cannot think of spark causing this
did you take the carbs completely apart and run then thru a heated sonic cleaner before putting back together?
did you follow the link and sync procedure in the service manual for your motor?
all the cylinders need the proper air to fuel mixture at the same time.
that old of a motor might have mechanical timing advance.
make sure it is doing what it should be when it should.
that should be part of the link and sync procedure -
I'll do link and sync again. Didn't do it after cleaning carbs last time.Comment
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Made no difference but I did look at the plugs again and all nice light brown except one almost black. I'm thinking float level high on that cylinder or failing coil?
Like I said...compression all good and even......Comment
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Found problem...coil feed wire only holding on with a couple strands...green corrosion....touched it and it disconnected. yc.jpgComment
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Great to find a hard fault like that!Comment
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I'm tempted to yank/wiggle all the other coil feed wires.....
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Was it the lowest coil on the block?Originally posted by BQUICK View PostI'm tempted to yank/wiggle all the other coil feed wires.....Comment
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Nice find.Comment
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No..... middle oneComment
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damn it, Yamaha. it's only 38 years !Originally posted by BQUICK View Post
how is your steering bracket, hard to turn?
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damn it, Yamaha. it's only 38 years !Originally posted by BQUICK View Post
how is your steering bracket, hard to turn?
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Seems good but that reminds me I didn't grease it this year......Comment
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