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Discussion Starter #1 (Edited)
Sometimes, it just amazes me how my little black cloud can find me anywhere I go.

I just completed a new piston and cylinder installation and break-in, go on a couple good rides, everything is going well, and then I get to a bad spot in the trail on a hot day. It requires me to dismount and survey a path through a washout and boulder fall. At some point while it was idling and waiting for me to get back on it, the stupid little breaker box that controls the fan shorts out, and when I climb back on and go up the trail, I notice the temp light is on. @*#%!
So I shut it off and try to see how bad it is. There was no boiling over, no steam, and no loss of coolant. Just a bit of gurgling going on. I wiggle the wires to the box and get the fan going. It runs for a good 4 or 5 minutes, then shuts off. I turn the key and the temp light is still on. Wait 5 or 6 minutes and turn it on again and the light is off. Gurgling stops. I think I dodged a bullet. Start it up and it seems to run fine. Temp light never comes on again. So I ride it 20 miles out, and ride it 85 miles the next day. No problems. Then the morning of the second day after, it starts a bit hard, shakes, and idles weakly. Shit. I know something is up. So I tear into it and discover the rear intake valves have zero lash. Shit. Fronts are ok.
So, I don't have a clue how long that temp light was on, but apparently long enough to either tulip the valves, stretch the stems, or fry the seats. Or all three. Please tell me I'm wrong.
I know the valves were good and set perfect just 800 miles ago when I installed the new piston, and I hadn't had to touch them in several thousand miles before that.

And why only screw the rear and not the front? Does the rear stay that much hotter because of where it sits?

My only hope is that the valves did whatever they are going to do, and now that I've adjusted them, they will stay clearanced for many more miles. Because if I have the shrinking adjustment interval going on again, well....no, I'm not going thru that again.

Goddamnit. Of all the bad luck.馃槨

I suppose the good news is:
The plugs look good.
There's no apparent oil burning, so the piston and cylinder have been spared.
The oil looks good and smells fine.
From what I could see of the cam and chain, they looked ok.

If this was a cast iron block and heads, I don't think I'd even worry one minute. But being aluminum, and suddenly having valve issues worries me.馃槦
 

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Set the valve lash, bypass the breaker and ride. I took mine out years ago and fan works fine. I did have over heating issues a couple years ago but I solved that with a ebay radiator and a spal fan. You can also get trail tech inline temp gauge.
 
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I think it may be possible the rear intakes were getting closer then you think before the overheating. On the other hand, intake valves are cooled partly by the fuel charge coming in so they won't be as hot as the exhausts but...they can be damaged by other things first like water or particle ingestion. My own Brute got the front intake valve seats and cylinder walls slightly damaged from the breach in the base gasket caused by how the K&N mounted. That breach was on top so trash with the airflow fed into the front cylinder. Once fixed it quit but a little longer and I would have had a rear problem. So, what I am saying is I don't think the heat did this and the fact that it started after you had intake parts off says...something changed. I would inspect every piece..every boot..every seal and gasket..every part of the air filter very closely. I would also reach through and swab the intake track and look for any evidence of particles stuck to the walls. The answer is there...just have to dig deep enough. If course it could just be another shitty set of valves...:)

Something to check anyway.
 

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Discussion Starter #4
I think it may be possible the rear intakes were getting closer then you think before the overheating. On the other hand, intake valves are cooled partly by the fuel charge coming in so they won't be as hot as the exhausts but...they can be damaged by other things first like water or particle ingestion. My own Brute got the front intake valve seats and cylinder walls slightly damaged from the breach in the base gasket caused by how the K&N mounted. That breach was on top so trash with the airflow fed into the front cylinder. Once fixed it quit but a little longer and I would have had a rear problem. So, what I am saying is I don't think the heat did this and the fact that it started after you had intake parts off says...something changed. I would inspect every piece..every boot..every seal and gasket..every part of the air filter very closely. I would also reach through and swab the intake track and look for any evidence of particles stuck to the walls. The answer is there...just have to dig deep enough. If course it could just be another shitty set of valves...:)

Something to check anyway.
Well, that's somewhat of a relief. I know the fan comes on around 212 F, and the temp light comes on around 225 F, but I don't know how fast it climbs from there, or what temp does real damage.
I've already gone through all the dirty air checks a hundred times over the last few years. I've never found a bit of dirt in the tracts.
When I had all the seats cut wider last year, the valve lash problem went away completely. That's been almost 4000 miles ago now. It's just too much of a coincidence that the valve lash goes to zero two days after overheating. But stranger things have happened...
 

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Discussion Starter #5
So I took it out for a rip this afternoon. I really ran the hell out of it. Wot up every hill and flat. Ran perfect. Full power. No unusual noises. Valves ticking away. No overheating. No coolant loss.
I will let it cool down tonight and try to start it in the morning. Fingers crossed that it fires right up.馃槵
 

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Discussion Starter #6
Well it fired right up and idled fine today. I don't see any need to tear into it and check the valves at this time. I hope it stays that way for several thousand miles. Headed back into the desert soon....
 
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Well it fired right up and idled fine today. I don't see any need to tear into it and check the valves at this time. I hope it stays that way for several thousand miles. Headed back into the desert soon....
Dang man..you truly do have "wanderlust". I don't know anyone that rides as much as you do. :)
 

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Discussion Starter #8
Dang man..you truly do have "wanderlust". I don't know anyone that rides as much as you do. :)
This time of year, I ride nearly every day. It ain't a bad gig.馃槈馃槃
 

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Discussion Starter #10 (Edited)
Well, I checked the valves tonight. Front was good but the rear was tight again. Only went 180 miles since last adjustment. Guess I'm popping the head off tomorrow to see what's going on. My machine shop is going to love to see me again so soon.馃檮
 

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Discussion Starter #11 (Edited)
Started it up to run it into the garage, and didn't notice any smoke. Got in the garage and had to move it out after letting it sit 20 minutes and it made a big puff of blue smoke. Wtf?
Shut it off let it sit 15 minutes, fired it up, no smoke. Let it sit 15 minutes and fired it up again and blue smoke comes out. Double wtf?
So I'm thinking ok, the intake valves were open all the time so the compression must have blown a valve seal off somewhere. No big deal. Gotta check what's going on with the valves anyway, so I'll see if a seal is off. Get it apart today and all the seals are perfect. The intake valves are clean as a whistle. There's a really thin bit of real dry brown stuff in the exhaust valves, and the combustion chamber has carbon on it, though lighter than I've seen before. One intake valve is edged, the other ain't bad at all. Seats look ok.
So where did all that smoke come from? It has not done that at all on any rides lately. Literally just started yesterday. So confused....
Do I need to tear into the front cylinder and see if one of those seals popped?
Is this a normal amount of carbon for a freshly broken in piston? I woulda thought it should be cleaner than that for just 900 miles?
Any thoughts appreciated.
 

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Discussion Starter #12 (Edited)
....
 

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Discussion Starter #13
75618
 

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Discussion Starter #14
75619
 

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Discussion Starter #15
75620
 

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Those exhaust seats look pretty much like the valves are not seating completely ?
 

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Discussion Starter #17
Those exhaust seats look pretty much like the valves are not seating completely ?
Yeah, it's possible. There's coloration on the exhaust valve stems too. They held vacuum 900 miles ago when I installed the rear piston, but overheating it may have changed that.
 

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Discussion Starter #18 (Edited)
Those exhaust seats look pretty much like the valves are not seating completely ?
Yep, you're right. Machine shop just called and said I need 2 intakes, and two exhaust valves. The exhaust seats took a beating.
 

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Discussion Starter #19 (Edited)
What an unfortunate chain of events...
The relay for my led light bar goes out, so I'm in there pulling on wires to replace it, and accidentally wiggled the wire going to the fan breaker. That in turn shuts the fan off which makes it overheat which takes out my valves and totally ruins my day.馃が馃が馃が馃が

Kawasaki was not too smart putting a piece of shit $4 fan breaker in these machines to protect a $3500 engine!
 

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Here's what my stock pistons looked like when I pulled them to do the big bore. Stock jetting and one cylinder looks a little richer than the other but both are dry, no signs of oil burning. I think they had around 1400 miles on them but it was a few years ago so i'm not 100% on the mileage but it shouldn't matter if they have 1000 or 10000 miles on them.

75623
 
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