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Old 08-12-2014, 07:19 PM   #1
Umarth OP
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Joined: May 2011
Location: Tramping arround the world for a bit with Big O
Oddometer: 348
LC4 100,000 preventive rebuild

Hi all!

Back from my trip from Canada to Ushuaia and then Brazil. Trip got cut short due to injuries but will resume at the end of next summer!

My 2006 KTM 640 Adv, aka 'Big O', is now at the 100,000 km (60k miles) mark and since i'm planning on putting on another 100k on it the next few years (Africa and Mongolia be a calling) I figure now would be a perfect time to tear into it, check every nut & bolt and change what needs to be changed.

Two things are pushing me to due a full teardown:
- the 'bad reputation' of lc4's as far as lomgevity goes,
- back in argentina, the bike started detonating more and more.

So at the moment, here is how Big O stands...





The first surprise, when tearing the engine open, was the state of the cylinder bore: the nikacil coating was in perfect shape! No perceptible scratches or anything. Still, I sent it to get measured for wear and see what size piston i'll put in.

The piston and rings where in perfect shape with just some slight scuffing marks on the piston sleeves. Talking with my dealer, it seems that the carbon deposits on the piston and the head was sufficient to actually cause detonation. Next time i'll know and just treat it to some carbon remover every once in a while. Good news is: nothing cracked or damaged!

With the engine case split, i started checking the parts for wear...

Both oil pumps are at half the tolerated clearances so there good to go. But there is some scuffing and marks on the inside part of the cover and at the bottom. Hard to see in the pic but some of the grooves are deep enough to catch your nail.



Read the rebuild by Gunnerbuck, he had a few pumps to choose from and commented that he passed on one that had less wear than an other because it had a history of seizing. Wondering, what causes them to seize?

Speaking of oil, one of the two oil 'jets' that keep the connecting rod lubricated was partially clogged. Would really have been nice if they had made it cleanable with out taking the cylinder off!

The connecting rode's bearing showed NO WEAR. But, i'm having it serviced anyway as i want another 100kkm trouble free out of it. This is good example of why i'm doing this preventive maintenance: contrary to when your 'close to home', where breaking down just means you loose your week end, an engine failure in the middle of Africa or some other remote land, can put you in danger. So, a few bucks now for peace of mind later sounds like a good trade to me.

The clutch disks had NO measurable wear! These things will definitely outlast me! The clutch basket does show some wear. Wondering if I should leave it alone or try to buff the marks out?






The transmission gears, on the other hand, do show some wear and tear: some pitting and some surface erosion. Some teeth look to me like they wore away the hardened surface. But i'm just guessing here. What do you guys think? Time to replace some gears or are they fine?







The main shaft's shows only slight scuffing.





The kick starter gear are mint. Mind you, i've not had to use it much.


And, lastly for this post, the splines for the counter sproket show some wear. This an issue you think?




All in all, so far i'm beyond impressed at how very little wear i'm seeing! Really starting to think that KTM's bad rep is BS... but then, a sampling of one is nothing more than that... ;)

More to come soon...
-J
Ps: any and all comments are more than welcome!
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Old 08-12-2014, 10:32 PM   #2
NevBlu
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Location: Carson City, NV
Oddometer: 46
Full engine rebuild - me too

Quote:
Originally Posted by Umarth View Post
Hi all! My 2006 KTM 640 Adv, aka 'Big O', is now at the 100,000 km (60k miles) mark and since i'm planning on putting on another 100k on it the next few years … I figure now would be a perfect time to tear into it, check every nut & bolt and change what needs to be changed.

Two things are pushing me to due a full teardown:
- the 'bad reputation' of lc4's as far as lomgevity goes,
- back in argentina, the bike started detonating more and more.

With the engine case split, i started checking the parts for wear...The connecting rod's bearing showed NO WEAR. But, i'm having it serviced anyway as i want another 100k km trouble free out of it.

All in all, so far i'm beyond impressed at how very little wear i'm seeing! Really starting to think that KTM's bad rep is BS... but then, a sampling of one is nothing more than that... ;) Ps: any and all comments are more than welcome!
Wow, now that's a ride to the tip! Glad you had success with the LC4.

I have a 2001 KTM LC4 640, that I am doing a full engine rebuild after 20,000 miles. I just finished posting the rocker cam rebuild.

Picked up my crank from the machine shop today. Here is the original connection rod bearing seize that started my reason for a motor tear down. I still want to determine how much is the riders fault and how much was missed preventive maintenance too. I will follow along with your rebuild.

The obvious items to rebuild are water pump, valves, piston, and heavy wear bearings. Good luck.
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Old 08-13-2014, 11:33 AM   #3
gunnerbuck
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Quote:
Originally Posted by Umarth View Post

Both oil pumps are at half the tolerated clearances so there good to go. But there is some scuffing and marks on the inside part of the cover and at the bottom. Hard to see in the pic but some of the grooves are deep enough to catch your nail.



Read the rebuild by Gunnerbuck, he had a few pumps to choose from and commented that he passed on one that had less wear than an other because it had a history of seizing. Wondering, what causes them to seize?


-J
Ps: any and all comments are more than welcome!
The one oil pump I had mounted and then took off my rebuild was very stiff to turn, even with oil on the shaft.. It measured the tightest tolerance but I worried that with it being so stiff to turn it would generate heat and possibly seize... The biggest cause of pump seizure will be from debris making its way into the pump..

As you have the engine ripped down completely you can go expensive and replace all the bearings, or go economy and replace the ones that are prone to wear...

If it was my project I would replace the 2 needle cage case bearings, one on the mainshaft, the other on the countershaft... I would take the countershaft and slip a new sprocket over the spline and see if there is much wiggle play, if the play is minimal I would reuse the shaft... I would also replace the countershaft roller bearing as it is pretty cheap and takes a lot of stress as often these bikes get run with a too tight of chain at some point in their life... As for the mainshaft bearing, if it is still looking in good shape, tight and spins freely I would leave it be plus the new one is around $120 now... If you do remove it and replace it you risk expanded the case as to where the bearing may rock and move at some point from clutch action in the future... If you still decide to replace it use retaining compound on the new bearing before you press it in to help lock it in position.. I would leave the crank end bearings if they still run smoothly, these things are massive and have a long service life... For the top end, if the cylinder does not show hone marks from top to bottom I would have the shop run a couple passes with a diamond hone and measure.. Reuse the same piston and replace the rings, make sure you check and set the ring end gap before assembling.. Last would be to perform a valve job as the sealing properties are probably far from perfect after the miles logged...
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Old 08-13-2014, 01:26 PM   #4
clintnz
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Interesting stuff, at 95K my gearbox was fine but the piston was well worn & the big end was on the way out.

Some great advice from Gunner above, I'd measure up & inspect the piston very carefully before putting it back in though... would probably splurge on a new one myself.

Cheers
Clint
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Old 08-13-2014, 08:36 PM   #5
NevBlu
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Location: Carson City, NV
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Endorse crank rebuild

[QUOTE=Umarth;24833600]Hi all. My 2006 KTM 640 Adv, aka 'Big O', is now at the 100,000 km (60k miles) mark and since i'm planning on putting on another 100k on it the next few years (Africa and Mongolia be a calling) I figure now would be a perfect time to tear into it, check every nut & bolt and change what needs to be changed.

The connecting rode's bearing showed NO WEAR. But, i'm having it serviced anyway as i want another 100k km trouble free out of it. This is good example of why i'm doing this preventive maintenance: contrary to when your 'close to home', where breaking down just means you loose your week end, an engine failure in the middle of Africa or some other remote land, can put you in danger. So, a few bucks now for peace of mind later sounds like a good trade to me.[QUOTE=Umarth;24833600]


I am glad you had so many miles and no doubt cool experiences with your long ride. From my perspective, I will endorse rebuilding the crank just as a preventive measure. Really Africa and Mongolia in your future does NOT need extra mechanical problems. Murphy's law will arise, yet you can fend off some of this law.

From my side, I am pleased to take delivery yesterday of my new crank, so I have too share. Crank out-to-out dimension is 2.557" without the crank races. It looks good and I am awaiting getting it together for a possible Baja ride in Nov. 2014. Whoopee!

This will be my first engine rebuild since the Bultaco days. Ok, so I've ridden since before a car driver's license.
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Old 08-13-2014, 08:49 PM   #6
_cy_
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better fixing ahead of time with you deciding when/where vs it breaking down and deciding for you.
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Old 08-13-2014, 08:55 PM   #7
ragtoplvr
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The gears are shot. any of them with the surface pitted are gone, and the mating gear needs replaced.

Rod
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Old 08-13-2014, 10:15 PM   #8
bmwktmbill
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For the clutch basket, I've buffed mine several times with a Dremel and no issues, smooth as silk.

I am running a BMW airhead with close to 200K miles on the piston and chrome rings, Nikasil bore. It still runs fine.

Wish I new more about transmission gears, maybe they could be sprayed if that's cheaper?

The detonation would bother me too and the why?

bill
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The faster it goes the faster it breaks.
And high performance=high maintenance.
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Old 08-14-2014, 04:51 AM   #9
davesupreme
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find a steel clutch basket... they don't do that.....
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Old 09-13-2014, 12:33 PM   #10
NevBlu
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Thumb Oil passage on LC4 cylinder case vs. gasket blockage

Quote:
Originally Posted by Umarth View Post
My 2006 KTM 640 Adv, aka 'Big O', is now at the 100,000 km(60k miles) mark Speaking of oil, one of the two oil 'jets' that keep the connecting rod lubricated was partially clogged. Ps: any and all comments are more than welcome!
I am rebuilding my 2001 KTM 640 and in addition to general mileage, heating, and oil issues, I would like to determine 'probable' contributing factors that caused the crank rod bearing to completely disintegrate. I suspect that several contributing factors occurred that will be large lessons for increasing my awareness and preventive maintenance. Simply stated better care and quality clean oil.

Discovery and question. I recently noticed the cylinder base gasket covering an apparent oil passageway on right side case, see red arrow in photo. I haven't yet looked at the repair manual, but look at the photo below. I will be looking at the oil circulation diagrams too. There is a recessed oil jet located just interior from where arrow is shown. I will try to remove this and clean with compressed air and cleaner too. After speaking with the KTM parts man, it is apparent that under the gasket there is a machining recess, plugged with a brass set screw. Now I feel better and won't worry too much more.
So any tips for the proper removal of the oil jet? Are there different sizes?
Well it seems that asking a question then allowing yourself to ponder even the simple things, answers and good methods lie right in front of us. Just a spray of penetrating oil, letting it rest, then with a flat blade screw driver with crescent wrench for torque, this little brass jet spins right out. It looks just like a Mikuni main jet, even stamped '80'. Verified that this oil passage way is clear and sprayed some compressed air through it. Guess it is good to go after reinstalling with some blue, Permatex threadlocker.
What advise do others offer when reassembly begins regarding the gasket?
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NevBlu screwed with this post 09-13-2014 at 05:46 PM Reason: new information
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Old 09-13-2014, 06:49 PM   #11
NevBlu
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Oil passage ways & crank case oil jet

The right side case has an oil jet that sprays oil to the crank area and thus splash lubricate the connecting rod bearing. The passageway has a brass screw stamped '80' that looks very simllar to a Mukuni jet. The jet is displayed on the top of the case. Verify that this passageway is clear while rebuilding the lower end.

Photo shows some safety wire to allow a better understanding of the oil passageways. The Oil jet is threading into the right side where wire extends out.

The left machined hole allows oil to drip into the right side crank bearing. Look at the tiny bit of light that illuminates in the crank bearing area.
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Old 09-13-2014, 10:00 PM   #12
gunnerbuck
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Quote:
Originally Posted by NevBlu View Post
The right side case has an oil jet that sprays oil to the crank area and thus splash lubricate the connecting rod bearing. The passageway has a brass screw stamped '80' that looks very simllar to a Mukuni jet. The jet is displayed on the top of the case. Verify that this passageway is clear while rebuilding the lower end.

Photo shows some safety wire to allow a better understanding of the oil passageways. The Oil jet is threading into the right side where wire extends out.

The left machined hole allows oil to drip into the right side crank bearing. Look at the tiny bit of light that illuminates in the crank bearing area.
The jet stamped 80 is sized accordingly to give the max spray stream to the underside of the piston without robbing from the line that feeds the backbone which passes through the spin on filter and on to the crank ... In 03 they replaced the mikuni style jet with a jet nozzle and in 05 they went to a dual setup where they used 2 smaller sized jet nozzles to spray the underside of piston..

You should have really started your own build thread as your interesting observations and questions are better kept together that way instead of being spread out through several different threads..
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