Honda GXV340K1 Smoking

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  #1  
Old 10-02-06, 12:38 PM
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Post Honda GXV340K1 Smoking

I bought a used "supposedly seized" honda harmony rear engine rider with the GXV340K1 engine. It appears to have been sitting awhile. After some investigation I found that the engine was not seized as it turned over fine though would pop thru the carb and not start. More investigation found the exhaust valve rocker arm was broken in half. Figuring that there had to be a good reason the rocker arm broke - like a stuck valve - I swapped rockers just to see if in fact the valve was free - it was. Both push rods are fine also. To make a long story short, ordered and installed replacement rockers for both valves, set the valve clearance at TDC. Changed the oil, filled the tank and it fired right up. Runs fine except that it billows blue smoke when first started, then goes away, then comes back after advancing the throttle all the way while driving. When I stop, retard the throttle it stops billowing after a minute or so.

Rings, valve seals, head gasket or all the above?

Thanks
Ed
 
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  #2  
Old 10-02-06, 11:23 PM
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Hello Ed,

While it could be a number of things, chances are it's the rings. These engines are very durable, and usually a cylinder honing and ring replacement are all that's needed to get them back in good shape for a looong time.
 
  #3  
Old 10-03-06, 10:08 AM
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Thanks

I figured as much. At least the ring replacement will also resolve the head gasket question.

My only concern is why the rocker arm broke in the first place - defective part? I would "think" that if there was something mechanical binding or locked such as a stuck valve that the pushrod would have bent long before there were enough pressure exerted on the rocker to break it in half.....

I'll just throw some "Engine Restorer" in to try and cut down on the smoke for the few remaining mows of the season here in good ole New England and rip it down over the winter - like I don't have enough projects to do this winter as is :-)

Ed
 
  #4  
Old 10-03-06, 11:33 AM
Azis
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I would guess that this "supposedly seized Honda..." actually was or did seize. Without knowing more of how or what was happening during the actual event it may not be possible to find out. Inspection of internal parts may reveal more. Perhaps too late now but inspecting the oil for metal is the easiest.
If it had been run in an extreme lean condition it may have over heated and over-reved even. Over heating can cause the piston/rings to basically weld them selves to the cylinder. Sometimes this can be freed up. Over-rev can cause the parts in the valve train to float, basically not remain in contact with each other and instead start beating each other until the weakest link gives.
If it seems to run ok cept for the smoke and inspection shows nothing obvious, rings and hone should do it. Honda's r perty tuff
 
  #5  
Old 10-03-06, 02:26 PM
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Honda

I don't know too much about the history of this machine. I bought it for a song off eBay from a small engine repair person who purchased it from a customer as-is. The story as I was told is the customers kid was mowing the lawn one day and it just died. The customer didn't want to sink the money into the repairs.

My guess would be this is probably true - due to not putting oil in it and overheating. There were a few other small items such as missing spacers on the front wheels and loose wheel bearings that make me think there was never even the slightest preventative maintenance done during the customers reign of ownership. Just drove it till it died. Sounds like my wife :-)
 
  #6  
Old 10-04-06, 12:15 AM
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Only disassembly will tell. If it did lock up, then there may be damage to contend with. I have seen a broken rocker arm or two on hondas. Right through the center at the hole for the stud. Broke for no apparent reason, and I imagine that was the case on this one too.
 
  #7  
Old 10-05-06, 11:23 AM
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Broken Rocker

Same here - right thru the stud hole
 
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