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Discussion Starter #1
Last couple of rides, there's been a bit more oil burning than usual. It's all coming from the rear cylinder. It's got 12,000 miles on it. (Front is basically new). So I figured I'd do a compression test to see how bad it had gotten. Came back at 78 psi. Front was 75. So I'm thinking one or a couple of the valve seals have popped off again. DAMN!
So should I just order some Kibblewhite spring loaded seals, and call it good? Or should I spend the big bucks and rebuild the whole cylinder? I think I know what NMK is going to say....馃槈馃槃
 

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Last couple of rides, there's been a bit more oil burning than usual. It's all coming from the rear cylinder. It's got 12,000 miles on it. (Front is basically new). So I figured I'd do a compression test to see how bad it had gotten. Came back at 78 psi. Front was 75. So I'm thinking one or a couple of the valve seals have popped off again. DAMN!
So should I just order some Kibblewhite spring loaded seals, and call it good? Or should I spend the big bucks and rebuild the whole cylinder? I think I know what NMK is going to say....馃槈馃槃
Hay now....I've gotten cheap in my old age...lol. I say confirm that it is just the valve seals and just do those. The compression is more then close enough and unless the oil ring is gone, they all should be in about the same condition. On the exhaust valve stems you should be able to see coking down the stems to the heads if the seals are leaking. Tougher on the intakes cause the fuel charge is always cleaning them off...but if it sits a while some oil will travel down the stem. Can always pop-the-top and take a look I guess. The rear cylinders usually loose the exhaust valve seals first though.
 

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Discussion Starter #3 (Edited)
Hay now....I've gotten cheap in my old age...lol. I say confirm that it is just the valve seals and just do those. The compression is more then close enough and unless the oil ring is gone, they all should be in about the same condition. On the exhaust valve stems you should be able to see coking down the stems to the heads if the seals are leaking. Tougher on the intakes cause the fuel charge is always cleaning them off...but if it sits a while some oil will travel down the stem. Can always pop-the-top and take a look I guess. The rear cylinders usually loose the exhaust valve seals first though.
Sounds like a good idea.
Sure wish there was a way to put the seals on without removing the whole head.
 

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Sounds like a good idea.
Sure wish there was a way to put the seals on without removing the whole head.
Sounds like bore and stroke time with some 30's! Oh wait.. thats what people do here to decrease their life expectancy! :)
 
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Discussion Starter #5
Well, got the rocker cover off and it doesn't look like any of the valve seals are floating. You know what that means.....馃ゴ
 

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馃槵 Time for a rebuild. Or just put some Slick50 in and run the crap outta it!!!! 馃槀
 
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Discussion Starter #8
How does the plug look compared to the other?
The front is picture perfect. The rear is nasty. Looks like a layer cake made from campfire ashes. Lol.
 

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The front is picture perfect. The rear is nasty. Looks like a layer cake made from campfire ashes. Lol.
Then it's either intake valves or rings. If there is more nastyness on the side of the plug that when tight faces the intakes, then it's probably them. If it's even all the way around...it's most likely rings.
 

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Discussion Starter #10
Then it's either intake valves or rings. If there is more nastyness on the side of the plug that when tight faces the intakes, then it's probably them. If it's even all the way around...it's most likely rings.
I'll get a better look at the plug when I get the head off.
Since it has all new valves, seals, seats, and no evidence of a seal popping off, and the fact that it has 12,000 on the piston/rings, I'd be willing to bet that it's not the intake valves doing all the burning.
The rear cylinder was not burning any oil last fall when I replaced the front piston. But slight oil burning started within 1000 miles, and gradually got back to levels it was at before I did the front. Then within the last three or four rides, it got considerably worse. The last ride I went on was 65 miles, and it burned through slightly more than half the dipstick.
 

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I'll get a better look at the plug when I get the head off.
Since it has all new valves, seals, seats, and no evidence of a seal popping off, and the fact that it has 12,000 on the piston/rings, I'd be willing to bet that it's not the intake valves doing all the burning.
The rear cylinder was not burning any oil last fall when I replaced the front piston. But slight oil burning started within 1000 miles, and gradually got back to levels it was at before I did the front. Then within the last three or four rides, it got considerably worse. The last ride I went on was 65 miles, and it burned through slightly more than half the dipstick.
Screw-it,- it's time then. :)
 

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Discussion Starter #13

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Discussion Starter #14
Finally got around to taking the head off and popping out the valves. The exhausts look like crap, the intakes look brand new, the combustion chamber looks like the tar pits. The valve seals were all on good, but it looks to me like they were still leaking down. But there is some dry stuff on them too like maybe the oil ring is bad. So at this point, I don't know if I should go forward with installing a new piston and cylinder, or just do a new set of rings with some honing, or just put in some viton seals? What say you?
75423
 

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Discussion Starter #15
75424
 

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Discussion Starter #17
To me that's even enough to be coming from below.
You're the one who can read buildup, so if you're saying it's rings, then I believe you.馃槈
To me, it just looks like shit.馃ぃ
 

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You're the one who can read buildup, so if you're saying it's rings, then I believe you.馃槈
To me, it just looks like shit.馃ぃ
Looks like a lot...be sure to check the bore from top to bottom for any oddities like washboarding or out of spec tapering, scars....ect. Those exhaust valve seals may have been leaking a little as one looks worse then the other.. but I assume you are going completely through it and giving it whatever it needs ...even guides..so..
 

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Discussion Starter #19
Looks like a lot...be sure to check the bore from top to bottom for any oddities like washboarding or out of spec tapering, scars....ect. Those exhaust valve seals may have been leaking a little as one looks worse then the other.. but I assume you are going completely through it and giving it whatever it needs ...even guides..so..
I've bought all the stuff to completely overhaul the rear cylinder, but I'm wondering if I really need to now. I guess I'll take the jug over to the machine shop and have them measure it. If it's ok, I might just throw a set of new rings on the old piston and send the sleeve and new piston back.
 

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If its that good then that's a good option but if it's anywhere close...you know what my feeling is. You ride more then anyone else I know...and I know you want the rear cylinder to last at least as long as that front one....lol.
 
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