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Discussion in 'Some Assembly Required' started by Krasniewski, Jul 27, 2011.
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
No and no. :huh
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.
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?
I basically had some K&N type filter material band clamped on - just a covering as there was no room for an entire cone.
Maybe - but it did die on its own, w/o gas down the cylinders.
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.
This is quite a gear heads brain teaser. Nothing really seems to add up. Im going to throw something out. I am not an expert on these 650 twins, but have worked on alot of similar engines. The camshaft drive sprocket is usually a press fit onto the crankshaft, nothing else holds it on except the press fit. Sometimes manufactures will use a key or pin of some type to locate the sprocket and to aid in preventing the sprocket from rotating on the crankshaft, but still the primary retension is a press fit. Some manufactures will use a "D" shaped crank OD and a matching gear "D" shaped ID, but again retension is by a press fit. Some manufactures use nothing but a round crankshaft and a round bore on the sprocket, again retained by a press fit.
I have seen engines (round bore, round shaft type) where the press fit was not to spec and the sprocket has turned and guess what the cam timing is off. This often happens during a backfire when the piston reverses travel and the inertia of the valve train keeps it moving forward.
I know you said you confirmed piston TDC with the marks. Did you confirm that while the piston was at TDC compression stroke that the cam sprockets were aligned correctly and the base circles were on the buckets (valves closed)? In the scenario of the cam drive sprocket "slipping on the crankshaft" the timing marks on crank position sensor would still be correctly timed with the piston, but the cams would not be.
Again this is just a shot in the dark, because I have no idea what method Kawasaki uses to retain the sprocket.
Also, dirt is really hard on the intake valves.
I wouldn't rule the dirt out, but the OP did not mention any dirt in the throttlebody or ports. The are some very small vertical scratchs, but the cross hatch is still visible. The another tell tale sign of dirt ingestion is blackish grey goo from very small metal particles mixing with oil, don't see any of that.
On my cam timing theory, he did not have leakage past the valves when doing his leak check, so that doesn't hold water either. Like I said before nothing adds up. Gross low compression, but no obvious leak path.
KR, you said the valves looked good how did you verify this?
I didn't... they just kind of look good. All I mean is that they look like they're seated, not cracked, etc.
Edit: I had figured that there may have been a broken cotter key or something that made the cams go off time with the sprockets, but they bolt on with 2 bolts, opposite and off center, making this impossible, as it turns out. I can post a pic later if you like.
Intakes were a bit dirty - but I think the cylinders look really quite good for dirt to be causing all this commotion.
I'm kind of hoping the head gasket was the culprit and she'll fire right up.
Ok - she's all back together and won't start. Exact same symptoms.
Hi mate firstly take a deep breath and step away from the motorbike.
There are enough people on this forum who can help you work out what the problem is.
As a mechanic most of what your saying is hard to follow and makes no sense.
To make it easier for some one to help diagnose these problems run through the following and type the results up in a list without any other views or observations.
1. is it getting fuel? (if you can get fuel pressure reading also check that the fuel is good)
2. is it getting a spark?
3. what is the compression reading on each cylinder with throttle wide open and cranked with a very good battery?
Goin' on vacation for a bit. Thanks for the tip.
Yes, yes and last one is ~70PSI. Haven't checked it since the rework though.
Pull the flywheel off and check that the key is still in one peice.
It sounds like your flywheel might have slipped and put your timing out.
Flywheel is used for charging circuit only on this engine. Ignition timing is controlled by crank position wheel and sensor on opposite side of the engine. Should verify crank position wheel is in correct relationship to TDC, I think OP said this was done already. Cam position to TDC should also be verified.
KR should recheck compression, determine if it is still low.
OK, so what I did before was take a long screwdriver and put it in the spark plug hole, when the that cylinder was TDC, I checked the crank timing indicator to make sure it was correct - it was. I checked the cam timing off the crank timing and made sure that was good as well. With the recent work I had to reset the cams obviously, but I'm 100% certain they're back to correct, original timing.
What I'm not certain about is the timing of the spark and/or fuel spray. It should all be ECU controlled and non-adjustable anyway, but it would be interesting to see if the she's sparking on time.
I do wonder if the low compression wasn't just from the motor being cold. The manual calls for to check the motor once it's been warmed up - but maybe the blanky and warm cup of milk wasn't enough and I really need to get it to run. Wouldn't that be nice.
did you pull the codes? can be done without a OBD scanner if you have the instrument cluster. doesn't cover everything, but it would be interesting to see if anything comes up.
dust/dirt you reported in the throttle bodies is not good, they should be spotless.
Check ignition timing with timing light. Watch crank timing indicator if the timing is between 40 - 0 degrees before TDC it should be ok to start.
Good point on compression, not sure if being cold will account for 100 psi drop. Pour a small amount of oil into spark plug hole, crank engine over without plugs in to cover cylinder walls, then do compression test. The oil will seal the rings perfectly and the cold engine condition is no longer a factor.
Whats the compression now?
i think a cold engine wold have more compression than a hot one
Is it possible you have the coils hooked up wrong?
Thanks for the info.
Do these motors use auto decomps on the camshafts?