Kawaski FD 620 D cylinder miss

Spikeit

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This is a twin cylinder and one cylinder has a dead miss. It may run great today, for a week or a month then starts missing. I've replaced the coil/wire, plug and adjusted the valves. I even replaced the carburetor which it needed anyway. It acts like a collapsed lifter but it doesn't have hydraulics. This has been happening on/off for two years and I'm out of ideas. My guess at this point is a sticking valve yet it NEVER backfires thru the exhaust or carburetor and having solid lifters one cannot stick shut. From my experience if this was the case it would/should have a bent push rod but I've checked and neither are bent. Just a dead miss always in the same cylinder that comes and goes. When the miss is gone it starts right, throttle is very responsive and runs like a striped ars Ape, hard and strong. Any ideas, anyone? What am I'm missing? Only thing I haven't done is a compression check because my gauge was on loan and got it back just yesterday. I've had the plug out, put my finger in the hole and it'll blow my finger out. If compression how can it have it for a day or week or month then suddenly loose it then in a day wk or month it suddenly runs great again until? :confused2:
 

BlazNT

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What is a dead miss to you? Please explain.
 

Spikeit

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What is a dead miss to you? Please explain.
Seriously? I don't mean to sound like a smart ars but maybe your trying to be cute? It's a term mechanics have used since before me, and still do. Ok, how would a DEAD CYLINDER sound instead? Dead as in DEAD, doing nothing positive nor negative, piston goes up/down, valves travel up/down but produces no combustion thus produces no power, isn't earning it's keep, DEAD, at times. While dead, plug still fires, valves work and NO blow by through the filler cap. Before last Tuesday it ran fine. Cranked it last Tuesday; dead miss. I may start it today and it'll run fine. I never know.
 

EngineMan

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What did you set the valve clearance to...?
 

Spikeit

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What did you set the valve clearance to...?

Off the top of my head I can't recall but it was per Kawasaki specs. I'll start it again tomorrow to see if it still misses or runs normally. Whether it misses or runs right, I'll do a compression test.
 

EngineMan

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The valve clearance should be set at 0.25mm (0.01in) and the cylinder compression should be 170psi MIN, and the next time it goes bad check the coil resistance on that cylinder, both primary and secondary, you could have a bad connection on one of the connector block(s) so check them out, Pulser coil to Igniter, Igniter to ignition coils.
 
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7394

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Perhaps the term" Intermittent miss" would be more appropriate.
 

7394

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Either way... :laughing:
 
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