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Discussion Starter · #1 ·
I've got a 23hp FH680V AS15 v-twin. It's using a lot of oil, also oil gets black right after oil change. took air filter off and inside is all oil. took breather cover off and filter in there is half full of oil. is reed valve bad?? I couldn't tell by looking at it. sometimes there's a big puff of smoke when I first start it, but I never see it smoking when it's running, but sometimes I smell it. Engine runs perfect with more power then when it was new. 1000 hr's.
 

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I would check to see if you have a head gasket problem. Maybe a cylinder leakdown test would be in order to better pinpoint the problem as it sounds like combustion is making its way into the crankcase.
 

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Hi HayBaler,

I noticed that you posted "1000 hours". Has this motor been rebuilt recently?

If it has, maybe, just maybe a ring was installed upside down.

If it hasn't, the 1000 hours is probably the problem.

sorry,
echoman
 

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there are oil drainback holes in the cylinder head and gasket. if it blows between the cylinder and drainback hole it'll pressurize the crankcase and blow oil past the rings and out the breather tube. kohlers are famous for this, but i've only seen it on the little kawis.

combustion can also get in the crankcase past worn rings. a leakdown test will show this.
 

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It's an air cooled engine, so that theory doesn't make sence.
That theory makes perfect sence. If the head gasket blows between the cylinder and the valve train it will pressurize the crankcase and blow it back out the breather. I dont see it too often on Kawi's but have seen it a few times on kohlers and a lot on older briggs overhead valves. Being an air cooled or a liquid cooled does not make any differences but thanks for making me look smart.
 

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Discussion Starter · #14 ·
your right, liquid or air cooled would make no difference at all. I knew that one would get you guys riled up. I was just hoping you guys would tell me it's the read valve and It would be simple. I'm just gonna throw rings and head gaskets at it over the winter in my free time. I have all the cylinder hones and ring compressors from when I was a kid

That theory makes perfect sence. If the head gasket blows between the cylinder and the valve train it will pressurize the crankcase and blow it back out the breather. I dont see it too often on Kawi's but have seen it a few times on kohlers and a lot on older briggs overhead valves. Being an air cooled or a liquid cooled does not make any differences but thanks for making me look smart.
 

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Discussion Starter · #15 ·
UPDATE: I actually took the heads off and the way this engine is designed it would be impossible for cumbustion pressure to get back into the crankcase. there is a dummy port in between the cylinder and the port the valves run through that is just open to outside air. The head gaskets look brand new anyways. so now I'm back to square one.
 

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Discussion Starter · #17 ·
The engine sat overnight with the heads off and I took a look in the morning and there is oil running right out of both cylinders! the rings must be shot. I have ordered the parts. if anybody could tell me the torque on the connecting rods and heads that would be helpfull, or a link to buy a kawi engine manual cheap. Thanks in advance.
 

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The engine sat overnight with the heads off and I took a look in the morning and there is oil running right out of both cylinders! the rings must be shot. I have ordered the parts. if anybody could tell me the torque on the connecting rods and heads that would be helpfull, or a link to buy a kawi engine manual cheap. Thanks in advance.
Hi,

It has been many years since I had my shop, but I remember that it is important to measure the wear in your cylinder/s. A cylinder wears in a barrel shape (more in the middle than on the top or the bottom). If the wear in the middle is more than .0015 (one and one half thousandths) than at the top, the rings will be forced to flex extremely on each stroke and will soon fail.

Someone please bail me out of this one if I am wrong on the measurement. I am working on memory and it is somewhat worn.

If it is out of specs, then the motor should be bored and it may be better to buy a replacement from some low cost supplier like Kansas City Motors.

Good luck,
echoman
 
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