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-   -   Flushing Engine with Diesel (https://www.horizonsunlimited.com/hubb/kawasaki-tech/flushing-engine-with-diesel-25880)

oldbmw 6 Mar 2007 20:35

Quote:

Originally Posted by mollydog (Post 128891)

But two strokes are different than four strokes. Still, I don't think it will hurt it. The difference using motor oil is you can RUN the bike and really circulate the oil and heat it. This should give a better flush through the entire motor,
top end, oil feed lines, pump, clutch et al.

Patrick

What would worry me using diesel is most two strokes have ball or roller crank bearing (both big ends and mains) whereas fourstrokes (especially multicylinder ones) usually have white metal bearings which need oil pressure to run safely. But that is theory, I have no idea how it would work in practice. So I agree, use engine oil ( even thin engine oil)

lecap 12 Mar 2007 09:42

Mollydog: The decompressor is controlled by the rpm of the exhaust camshaft and a spring only.
If the engine rpm is below approx 600/min the spring pulls a weight in which in turn turns a plate with a pin making the pin protrude out of the base circle of the cam.
The system is quite ingenous and more important: Fail safe.
The KLR starts easily with the decompressor deactivated or removed. A broken spring will also only cause the decompressor not to decompress.
I will have a look into more "exotic" possibilities of decompressor failure. Must go to the workshop and have a closer look at a KLR camshaft later today and let you know.

OldBMW: Not too much need to worry about the white metal journals. They have quite good emergency running capabilities (which they need for cold start for example). Flushing with Diesel should not cause problems as long as you only crank but not run the engine. I would worry a bit about how to get the Diesel out of the engine afterwards.
No need to worry about white metal journeys on a KLR as it has none. Like the majority of four stroke single the KLR's main shaft runs in roller bearings same as the con rod big end.

Mr. Ron 12 Mar 2007 21:01

Quote:

Originally Posted by Paul Thoreson (Post 128836)
Andy! Hey, somebody's got to live the dream! Anyway, that's what employees are for! It's all about being a good delegator.

PatrickOT - Very interesting about the flush. I'm glad to hear that somebody has done it before. One (or two) side question(s): how did you get the bike back to civilization in order to do the flush? Or do you always travel with 5 liters of diesel fuel and 2.5 liters of oil just in case you tip over in a river crossing?

Thanks tons for your input guys. Well, MollyD, the hammer didn't work so I'm going to try something else.

Just a few side notes. It's a 2002 KLR650. The piston cracked between the first and second rings and was welded and machined down as good as possible. The problem began about 8.000 km later - just about enough time for the weld to start breaking apart. Every oil change the oil filter has lots of silver and black particles. The oil gets really really dirty more quickly than it should. I was using Castrol GP 20/50 mineral oil. (Just switched to Castrol semi-synthetic, which should give me a better range before having to change the oil again.)

About 1.500 km after each oil change, and the bike running perfectly with tons of power, it just dies. From one moment to the next it looses all of it's power and dies, literally. From running at 100km/hr, to the engine dying, but it's still in 5th gear, so it slowly slows down to a stop. I usually try to use the momentum that it has and release the clutch to push-start it, to no avail. Once we come to a complete stop, I try starting it for a few minutes without any luck. I turn the key off every once in a while and let it sit, then resume with the start button. Eventually it will fire and run perfectly for a few kilometers (sometimes until 10 or 20km), and then die again in the exact same way. After 3 or 4 of these episodes it won't fire again until I change the oil and clean the filter - then it starts up like she was new and runs perfectly for about another 1.500 km or so.

So to recap: the problem started after a piston weld. Now she runs perfect after every oil change, until the oil looses something of it's viscosity, then the problem returns. I change the oil and the problem goes away, temporarily.

For me, the problem is definately oil/particle related. I'm going to try to diesel fuel flush that PatrickOT used, and see what happens. If that doesn't work, I'll try some of the other suggestions.

It's pretty late here and I've got another long ride tomorrow, so I'm going to hit the hay right now.

Don't worry guys, I'll get back to you to let you all know how it all turns out. What I try, and what (hopefully!) fixes the problem.


This problem reminds me of an old DR125 i had when i was a kid. Would run fine, then die. Then run fine again, then die! WTF?? Turns out it was the electronic ignition module, it had a small crack in it. Sometimes it would work, then when it got hot, it died. Then it cooled off and would work again. A new one fixed the problem immediately.
I really can't see how the engine oil would cause this, or change it for that matter. My first guess is ignition, then fuel. The oil thing is just wierd luck?? in my opinion. I hope you work it out, keep us informed!

lecap 13 Mar 2007 09:13

Quote:

Originally Posted by mollydog (Post 128888)
...Maybe somehow it is being activated. No idea.
Patrick:scooter:

(talking about the decompressor)
I had a look at the decompressor yesterday and it's a no - no.
The decompressor can not start to decompress while the engine is running. The camshaft has to stand still (no force on flyweight) to engage the mechanism.

Although the engine seems to be busy eating its guts :-o I also think that this is not what actually causes the engine to cut out.
Have you tried to check if the spark plug fires when the bike does not start?

I don't think the case of a "magnetic shortcut" is very likely. The particles would rather accumulate on the flywheels magnets at low RPM causing the bike to cut out when idling.

Frank Warner 14 Mar 2007 03:31

To find out if temperature is the cause -
If the bike runs in rain ..
Then a good temperature reduction test for the electrical components is a splash of water - cools them down and if that makes it run .. then next time throw smaller bits of water on just one componet at a time to time which is the faulty one..

Paul Thoreson 22 Mar 2007 02:26

Sorry I didn't get back to you guys sooner on this, MollyD, it's just that I was a little busy doing, wait, what was it again...oh yeah, traveling.on.my.motorcycle, camping out, getting lost on purpose... I hope you can understand and forgive my tardiness.

Update: 2.600 km since the diesel fuel flush and the bike's still going strong. That's not bad considering that the last two times I changed the oil I was only getting about 1.000 km before the problem resurfassed. We'll see how long it lasts, but it should be good as new since the problem was definately oil/particle related. And it continues to look that way since the problem appears to be gone after an engine flush.

Method:

Empty Oil.

Clean/replace oil filter.

Add 5 litres diesel fuel to engine. Disconnect spark plug. Set bike on it's side and press start button a few times. Repeat on other side. Back upright hit the start a few times again. Drain diesel.

Check diesel for particles. If necessary, repeat process with another 5 litres (remember my case was pretty severe with tons of metal particles). Make sure to have patience and drain as much diesel out as possible.

Now add a _light_ engine oil (I used 30), reconnect spark plug and fuel lines, and start engine. Let run for 10 minutes or so. Empty oil and clean/replace oil filter.

Add oil of your choice and you're off!!! Enjoy the ride!

Like I said, 2.600 km into the new oil and she's running great. No sign of any problem, which is logical considering that the majority of the particles are out of the engine - tons of particles showed up in the used diesel and oil filter.

My word of advise: next time you're stuck in the middle of nowhere with a piston problem, either leave the problem piston in the engine until you can replace it, or, if you're going to weld the piston, change it out as soon as possible.

I'd like to leave this oil in the bike at least until the specified range just to see if the problem is solved 100%, but I think I'll do another oil/filter change here pretty soon just in case there are more particles in there doing damage. And then I'll just have to ride, ride, ride! as much as possible to see if the problem is still there. So, ladies and gentlemen, back to work!

Thanks for all the advise team. I'll keep you updated.

Mr. Ron 23 Mar 2007 14:55

Hey Paul, i'm staying in your Hostal now and using your internet service to write this letter! Small world, eh? Glad you sorted things out. Molly's right, wierdest thing i ever heard of!
BTW, great garage! I rebuilt my carbs and had some liners built for my panniers from the kind fellow next door. Maybe i'll see you on the road!
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