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Old 10-19-2010, 07:40 AM   #46
bmwktmbill
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Quote:
Originally Posted by Tseta
See here.

-T
Thats what I suspected, a huge main jet so too much fuel when running.
You would guess that with all the carbon.

Not sure if that is the cause of the piston problem/failure but I don't think it helped anything.

As for the metal pieces you found, maybe they are left over from changing the transmission mainshaft bearing long ago and they just found a home inside the cases.

I don't have much experience shimming a ball bearing crank but my son and I did one on a bevel drive Ducati. There were all kinds of instructions but we just put the cases together with too many shims and the crank would not spin freely so we took out the smallest shims and put it together again and it was free so that was 'good'.

That was many years ago, the engine still runs fine.
I have to read about shimming the 640 engine.
Thanks again Tseta for your work and pictures.
You are writing the 640 Bible.
bill
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'02 KTM 640 Adventure-lowered
"On the road there are no special cases."
Cormack McCarthy-The Crossing

The faster it goes the faster it breaks.
And high performance=high maintenance.
Bill Shockley

bmwktmbill screwed with this post 10-19-2010 at 07:58 AM
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Old 10-19-2010, 08:16 AM   #47
gunnerbuck
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To measure the crankshaft for shimming, the races must be off the shaft and sitting in place in the case bearings.... You then measure the depth of each case half from the gasket surface to the face of the bearing race... Add the 2 case half measurements together + the thickness of your new gasket and then you have the target measurement to shim to....

Now you measure the width of the crank with no races or shims in place and subtract this measurement from the above case half measurement...

With this number you arrived at after the subtraction you then will be able to figure out what thickness of shims you need to bring the play down to 0.03 - 0.12 mm....

You only need to reshim if you are going to replace the crank end bearings...

The races should be tight to the shaft and have no wiggle or movement... The one you show in the pictures that has movement should for sure be replaced... What could of happened is a chunk of debris may have gotten between the rollers and caused the bearing to spin it's race on the shaft...

When you replace the bearings measure the shims you take out from behind the old races... It is very likely that the shims required for the new bearings will be very close if not exactly the same as what you took out....

gunnerbuck screwed with this post 10-19-2010 at 08:24 AM
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Old 10-19-2010, 08:32 AM   #48
gunnerbuck
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Quote:
Originally Posted by Dirtybill
Not to rain on your parade but wouldn't it be cheaper and easier to get rid of the KTMs and get a good bike like a Husky?

That's what I did after my KTM grenaded and it was stuck in a KTM dealership while under warranty for 3 months of prime riding season.
Bill, You have made yourself unwelcome on many forums, I wonder why?

While Husky's are great bikes they are not perfect and have their problems as well...
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Old 10-19-2010, 09:00 AM   #49
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bmwktmbill: The large main jet may in fact have something to do with the bike's troubles. However, the owner says that the bike pulls cleanly and strongly with reasonable consumption. I have also read here (can't find just the thread now) on suggested settings for the Dell'Orto, and most seemed to recommend a main jet around this size, especially with a open exhaust and intake. This bike has a Wings aftermarket muffler and the airbox top has been hacked away almost completely (all by previous owners).

gunnerbuck: Thank you very much for the explanation. It makes the procedure clear to me now. The KTM manual is a bit vague on multiple points. I guess I will have to go out and buy a depth gauge with an exceptionally wide base. I have a depth micrometer, but it won't reach all the way across the crank cavity to the sealing surfaces to measure the case depth. I guess I'll also need vernier calipers with very long jaws, as none of my calipers reach onto the crank bearing surfaces.

KTMs versus Huskys.... How do you say it over there, across the pond? Haters gotta hate?



-T
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Old 10-19-2010, 09:21 AM   #50
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So, I took the crank to a few places to have them look at it. The verdict basically was that the crank is done.

The local KTM shop was friendly enough to remove both of the bearing races from the crank for me, using the official KTM heater/puller tool. Nifty piece of equipment, I must say.

For some reason, the bearing has spun here on the crankshaft.



The mechanics think that there is some heat damage as well. When you try the surface with your fingernail, you can feel that it is rough.

The other side has these kinds of marks.



The bearing race inner surfaces look like this for the "loose" side:



And like this for the "ok" side:



The outer surfaces and the rollers look just fine on both bearings.

The mechanics also told me something more about the upper conrod bearing.



Because the bearing shell is not centrally located, the oil holes in the conrod and the bearing don't line up anymore. This means that the piston pin was not receiving adequate lubrication, causing additional friction and heat here.



So, there are basically two options now. A new complete crankshaft with bearings is the easy and sure way out, but means also big bucks. One of the mechanics suggested that the crank could perhaps be welded back up, and then ground to size. Provided that I could find somebody with the knowhow and equipment to do this, it would still require new bearings and perhaps a new conrod (?). The cost with this option is a big question mark...

I checked out the transmission gears more carefully but found nothing alarming there.





Quote:
Originally Posted by bmwktmbill
As for the metal pieces you found, maybe they are left over from changing the transmission mainshaft bearing long ago and they just found a home inside the cases.
I have now come to a similar conclusion, as everything else checks out fine, there is really no place else the metal bits could have come from.

One additional thing I found. I measured some of the clutch components. The steel plates and the friction plates all measure like new, no wear there. However, the clutch springs were not ok. Three of them were within spec, while three others were noticeably shorter. I don't have the exact measurements with me, but the difference was enough that it couldn't reasonably be explained with just the springs wearing or fatiguing.

Perhaps the root cause of many of the engine problems lays in insufficient lubrication. Dirty and contaminated oil was floating around the engine, damaging the oil pumps and the bypass piston. The bypass piston spring has also been left unchecked for too long, causing even lower oil pressures in the bike. This in turn has led to spun bearings, and the rest is history...

Any input is appreciated.

Cheers,

Tseta
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Old 10-19-2010, 09:22 AM   #51
gunnerbuck
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Rather than buy an expensive depth gauge you could use a straight edge and a small dowel to do the measuring....

Put the straightedge across the case and then trim the dowel a little longer than needed to fit between the straightedge and the bearing race surface....

Take and file the dowel down carefully until it just fits in between the race/straightedge... You can then measure the length of the dowel with your regular caliper to get the # for that case half...

Use a second dowel to measure the other case half...
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Old 10-19-2010, 09:38 AM   #52
gunnerbuck
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Was your bypass piston spring sacked and below tolerance?

I wouldn't mess with trying to weld/repair the old crank assembly... A new one, while expensive {$414 US} would be the best and probably cheapest route in the long run ...
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Old 10-19-2010, 10:36 AM   #53
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Quote:
Originally Posted by gunnerbuck
Was your bypass piston spring sacked and below tolerance?
Oops, I thought I posted this info already. Yes, the piston spring was below tolerance and the piston itself had some scratches on it.

Good idea about the straightedge as well. I think I could fab something up.

I have an additional question about replacing the bearings in the case. The KTM manual instructs to heat the case (in an oven) to 150 degrees Celsius. The bearings then supposedly fall out. With this bike, I wouldn't want to replace any other bearings than the actual crankshaft bearings. So, how do I make sure that the other bearings don't fall out as well? I think a removed bearing should not be reinserted. Or will the heat harm the bearings anyway, making it so that I should replace all the engine bearings at the same time?

Cheers,

Tseta

-T
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Old 10-19-2010, 11:02 AM   #54
gunnerbuck
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When I removed the bearings out of the case I heated the case area around the bearing with a heat gun and then used a pin punch to drift the bearings out... The tapping on the roller and roller collars damages the bearing but it was going in the garbage anyways...

To install new bearings, put the new bearings in the freezer, warm the case and then the bearings slip in with little persuasion... Don't forget to replace the crank seal in the left case half...
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Old 10-19-2010, 11:11 AM   #55
makazica
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Tseta,

let me go back to the metal pieces you found on the magnet for a moment....
When I did the main bearing swap, I drilled some of the rivets on the bearing to make space to attach the hooks. I'm pretty sure that on my next oil change I found a metal piece similar to what you found ( the suspected gear tooth ) on my magnet. I went through all my photobucket galleries but can't find a pic...I'm not even sure I took one.

Could it be possible that the previous owner used a similar technique to change that bearing and that one piece of the bearing races facing towards the inside broke off...?

Still don't know what the other thing may be.

You started all this because the engine consumed oil....with that crack on the piston, the misaligned small end bearing and the shot crank bearing race...do you think that all this could cause the bike to consume 0,5L of oil?

Quote:
I have an additional question about replacing the bearings in the case. The KTM manual instructs to heat the case (in an oven) to 150 degrees Celsius. The bearings then supposedly fall out. With this bike, I wouldn't want to replace any other bearings than the actual crankshaft bearings. So, how do I make sure that the other bearings don't fall out as well? I think a removed bearing should not be reinserted. Or will the heat harm the bearings anyway, making it so that I should replace all the engine bearings at the same time?
Don't you think that you would be able to it with a heat gun or a propane/butane torch?

Code:
Yes, the piston spring was below tolerance and the piston itself had some scratches on it.
How often do you think the bypass spring and piston should be checked?

M.

AND YES, THIS IS GOING TO BE A CLASSIC!!
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Old 10-19-2010, 11:32 AM   #56
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Mak,

It is the orange 2007 LC4 Adventure that has the oil consumption problem. This bike (blue 1998 LC4 Adventure) has been with its current owner such a short time that no oil consumption trend has been seen.

It is possible that the pieces are from the previous mainshaft bearing change. The small cylindrical rivet looking thing probably is from that swap. The other pieces, I don't know. There are just so many of them. And more were found inside the cases when I split them.

Bypass piston check, maybe every 20 000 kilometers? I don't really know.

Gunner & Mak,

I am concerned about getting even heat when using a hot air gun. Is there danger of distorting the cases?

-T
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Old 10-19-2010, 12:39 PM   #57
gunnerbuck
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With the heat gun I don't think I really warmed the cases up much more than they get under normal operating temps, so there was no issues... I'm still running on those same bearing now and they have nearly 90,000 km on them...

If you chilled the bearing first and then warmed the case this method would work even better with less heat required...
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Old 10-19-2010, 07:32 PM   #58
chico33
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Tseta, Use caution when heating clutch side case to remove main bearing ,
transmission output shaft roller bearing has a plastic cage which can melt.
( don't ask how I know this ) .

chico33 screwed with this post 10-19-2010 at 08:12 PM
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Old 10-19-2010, 11:00 PM   #59
bmwktmbill
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Tseta, I have never checked my relief valve spring and I have an oil change coming up. There is a thread on removing it and checking it?

Could you post the specs and write a short explaination...and comment if it can be checked with the engine in the frame(if you have the time).

Thanks,
bill
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'02 KTM 640 Adventure-lowered
"On the road there are no special cases."
Cormack McCarthy-The Crossing

The faster it goes the faster it breaks.
And high performance=high maintenance.
Bill Shockley
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Old 10-20-2010, 03:37 AM   #60
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Well, the owner of the blue adventure has now committed "for the long run". Which means that I went and ordered lots of expensive parts from my local KTM dealer. The order included a new complete crankshaft assembly ($$$), a Pro-X piston, new crank bearings, new oil pumps etc. etc.

Bill, there was some mention about the oil bypass valve in Creeper's LC4 oil change thread. However, I will take some pictures and write a few lines about it, possibly already tonight.

Cheers,

Tseta
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