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Old 10-08-2011, 04:41 AM   #31
dentvet
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So did it die from water contamination or not? the sequence of events has me confused as to why the ignition or cam timing would have to be checked on an engine that was previously running fine.
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Old 10-08-2011, 03:10 PM   #32
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So did it die from water contamination or not?
Don't know... it's possible, but I don't know that it would have really killed the motor permanently since it was just at idle.

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the sequence of events has me confused as to why the ignition or cam timing would have to be checked on an engine that was previously running fine.
B/c it WAS running fine, but is no longer. I thought it was water in the fuel at first, but fresh fuel and plugs didn't fix the problem, so I'm looking to other things. If you think I should be looking looking elsewhere, I'm all ears.
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Old 10-08-2011, 05:29 PM   #33
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I have never measured compression just by turning the engine by hand, so not sure if you would get a reading or not. That said, 70 psi WOT cranking is not good. I have not measured compression on my ninja motor, but I have on similar displacement liquid cooled twin cylinder DOHC 11:1 ish CR engines and 200 psi not uncommon. Heck, old air cooled 2 valve 8.5:1 CR engines will crank out 130-140 psi.

One more thing on the compression, what altitude are u at? If you are 12,000 ft you might get a reading of 70 psi.

You could possibly make a temporary leakage check tool from your compression gauge or from an old spark plug, I have done both. Remove the gauge and check valve from the hose of the compression tool. Find some fittings and hoses to connect regulated compressed air to the gauge end of the hose. Now you can apply compressed air (100 psi is good) to the combustion chamber. Set piston at TDC and apply the air pressure. Listen and feel for air escaping through the intake, exhaust and oil fill. There should be only a very small amount of air coming from any of theses openings. This will not give you a leak % value, but will identify gross leaks. If your compression reading of 70 psi is correct, this will find your problem.

Using an old spark plug is similar. Break off the top of the plug and gut the hex and threaded part. Weld or braze a 1/8" pipe coupling to hex section (of course the weld has to hold air) and you have an adapter to get compressed air into the engine.
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Old 10-08-2011, 05:39 PM   #34
dentvet
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i think the key is that both cylinders read the same. anything catastrophic would probably only affect one jug. i guess if the cam chain jumped timing you could see this but it looks like you checked this out ok.

raw gas dumped down its throat could cause the intake backfire in a normal engine. i think spark occurs on the exhaust stroke as well and there is probably valve timing overlap so raw gas sitting there is going to go poof back through the intake

I would keep hunting for a fuel problem but if you have the opportunity, test your compression gauge on a known good running cylinder

sorry if i sounded annoyed, i was merely confused
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Old 10-08-2011, 06:39 PM   #35
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One more thing on the compression, what altitude are u at? If you are 12,000 ft you might get a reading of 70 psi.
I'm at about 10' above sea level. Ocean view, baby.

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You could possibly make a temporary leakage check tool from your compression gauge or from an old spark plug... snip.
Good idea - I'll get into it that as soon as I can. Workin' this weekend, but I'll see what I can do soon.





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Originally Posted by dentvet View Post
raw gas dumped down its throat could cause the intake backfire in a normal engine. i think spark occurs on the exhaust stroke as well and there is probably valve timing overlap so raw gas sitting there is going to go poof back through the intake
I don't think I mentioned it before, but down the intake you can see the fuel spraying (spray pattern looks good to my eye), however, for whatever reason (possibly bad timing, possibly not enough air getting sucked down the intake) fuel is accumulating in the intake port.


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sorry if i sounded annoyed, i was merely confused
No apology necessary, your point was valid to the max, and if anyone ssounds annoyed here, it's me, since I've been fighting this for the last month.

All input is appreciated.
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Old 10-09-2011, 05:58 PM   #36
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Tried out the gauge on a buddy's 70's R90/6, which registered 120psi. It's a 900cc twin with much lower compression, for those curious. Point being that I believe the gauge to be working just fine, and I really have a compression issue.

I think the head will come off soon.
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Old 10-10-2011, 09:26 PM   #37
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OK - I hooked up some air pressure to the cylinders and a good amount of air could be felt/heard in the inspection cover of the side case... so either air was getting past the rings, or to gasket was majorly jacked, or I'm doing it wrong (wouldn't be the first time ).

Right or wrong, I pulled the head. Pics below. The cylinder walls look good to me, but the pistons look a bit nasty.






Gasket is metal - can't really tell if was good or bad.

Head looks fine, though a bit nasty like the pistons. Valves look normal to me...




Anyway - I thought I'd find something obvious. So either I'm obviously missing something, or I'm barking up the wrong tree (again).

So... on to questions:

Am I missing something?

Pistons/head with so much crud - normal or not?

Should I pull the cylinders and look at the rings? I'm thinking yes, but what's the point if cylinder walls look good?

Is there a way to tell if the gasket was blown by looking at it? It's a metal gasket that looks normal to me. No water in the oil that I can see.
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Old 10-10-2011, 09:33 PM   #38
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looks,like lots of dirt to me. The cross hatch is about gone. Remove the cyl. and measure the clearence.
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Old 10-11-2011, 04:19 AM   #39
dentvet
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The head gasket would be eroded or etched at the bridge between the two cylinders if that was the cause for the low compression in both jugs.

I guess you might be looking at bad rings at this point but i would think the thing would have been burning lots of oil before it got so bad as to prevent the motor from running
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Old 10-11-2011, 06:24 AM   #40
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Pistons look ok to me, clean them, but the head looks like it has a bit of oil on the valves. You are that far, go ahead and pull the cylinders check the rings for breaks and check the ring gaps.
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Old 10-11-2011, 06:53 PM   #41
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Old 10-11-2011, 08:25 PM   #42
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Man, I'm thinking it's gotta be in the head gasket. The blowby into the crankcase usually makes me think it'd be rings, but you weren't burning oil or anything, nor was it down on power. Did you ever get the temp indication working? In other words, could you be sure you weren't overheating at all?
On the upside, now would be a good time to look into higher-comp lighter than OEM pistons
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Old 10-11-2011, 08:53 PM   #43
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Did you ever get the temp indication working? In other words, could you be sure you weren't overheating at all?
No and no.

The only temp indication is an overheat light (which probably should but doesn't turn on during the startup checks). I've never had the fan come on either... but it never really gets hot here and the KLR650/685 motor never kicked on the fan unless it was REALLY HOT, so it didn't bug me, plus, the motor was running pretty rich from the air intake being so restrictive.

My fear is that I get some sweet ass pistons and then I put it all together, and it really is an electrical problem, and it still doesn't run... wouldn't that suck.
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Old 10-11-2011, 08:59 PM   #44
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There seems to be a fair amount of wear on the top ring evident in the second from last picture. Also some strange wear on the piston just above the second ring and the second ring has strange looking vertical scratches. The cylinder also shows signs of vertical scratching (debri).

What were you using for air filters?

Maybe a combination of worn rings and then pouring gas down it would wash the oil off the cylinders and reduce ring sealing more.

When the engine was running last did it backfire at all?
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Old 10-12-2011, 07:02 PM   #45
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What were you using for air filters?
I basically had some K&N type filter material band clamped on - just a covering as there was no room for an entire cone.



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Maybe a combination of worn rings and then pouring gas down it would wash the oil off the cylinders and reduce ring sealing more.
Maybe - but it did die on its own, w/o gas down the cylinders.



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When the engine was running last did it backfire at all?
Before I did the intake, I'd get one large backfire once in a while from running too rich. After I did the intake it basically just idled ok, then sputtered and died.
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