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Old 12-31-2010, 04:33 AM   #151
Roarin
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Quote:
Originally Posted by Tseta View Post
Thanks for all the praise on the frame welding. I'd like to point out a major flaw and weakness in the frame weldings and fixings that I have done. KTM uses chrome-molybdenum-steel alloy as the frame material. The gussets, studs and bushings I have made, as well as the filler wire in the MIG-welder are just regular, mild steel. This is far from optimal. Keywords here are hydrogen embrittlement. TIG-welding, pre- and/or post-welding heat treatments and ChroMo-filler material are all recommended.

However... I have chosen to call this "good enough". Time and resources are always limited. Acquiring said equipment or materials is not always convenient or even possible. In reality, welds might hold even if they are made in non-optimal conditions with non-optimal materials and processes. I have done similar "fixes" on my bike and the third KTM in the stable as well, and they've held up well (so far...). The owners of the other bikes and I are willing to accept the risks of failure associated with this welding process.

Mak: Thanks!

Cheers,

Tseta
Nah -you'll be fine. You will only get Hydrogen embrittlement if you introduce water or hydrocarbons into the molten weld pool. Pretty hard to do with MIG or TIG. About the worst you may have done is dropped the ultimate tensile strength of the area from somewhere round the 800 Mpa range down to 600 odd. At a guess. At worst. Pretty sure a lot of race car chassis fabricators use 250-350 grade sheet for gussets etc. If you do any more TIG welding, just use ER70S2 filler. It will be close enough (and also reccomended) for the CrMo used in a bike frame.
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Old 01-01-2011, 10:05 AM   #152
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Roarin: Thanks for your reassuring words. I'm sure the welds will be "good enough".

Bmwktmbill: I blame the Finnish education system for my English skills...

-----

The first "smokes" were drawn from the 1998 LC4 engine today. It purred beautifully. Next week I will take it to the dyno for some running in.

-----

I also went for a new year's ride today. Things did not go so well...









-T
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Old 01-01-2011, 10:49 AM   #153
B-Rod
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Originally Posted by Tseta View Post

I also went for a new year's ride today. Things did not go so well...

I noticed your images contained the words 'smothered/carnage'. What happened?
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Old 01-01-2011, 11:08 AM   #154
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B-Rod: You'll notice that all of my images in this thread are in the directory /smothered/carnage/... Carnage is this winter mayhem, three times the fun with three LC4's. Smothered is just a word I once (a long time ago) came up with, when setting that directory up.

I left the previous post intentionally open-ended, a cliffhanger of sorts. I've understood that this type of drama might be enjoyed by some.

Today's ride was nice, up until the point the bike stopped working. I am fine, no damage to me or the bike. In fact, there wasn't even a crash. The bike just died on a straight section and refused to start anymore, even though there was plenty of fuel, the obvious electrical connections were ok, etc. (as much diagnosing as could be done in the cold). The good thing was that we were already heading back to the garage, and were already on plowed "main" roads. If the bike would have died in the forest, I would probably still be pushing it out from there.

Cheers,

Tseta
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Old 01-02-2011, 11:30 AM   #155
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Well, I figured out why my bike won’t start…

The sparkplug was my first suspect, or the plug connector and the ignition wire. There was something funky there, the plug’s thread-on SAE-connector had corroded and the threads on the plug had almost completely disintegrated. I installed a new plug, cleaned up the connector, and snapped a few mm’s off of the ignition wire to get a good contact onto the connector. A big fat spark was produced when the sparkplug was grounded outside the engine. No effect on the starting issue, though.

Next thought was fuel. I verified that the tap indeed was operational, and that the fuel was reaching the carb. It seemed that the problem might lie there, as the plug didn’t smell at all like gasoline, even after continued cranking (with the choke and or throttle at various positions). I emptied the float bowl and cranked the bike again. When opening the drain screw again, more fuel would come out of the drain hose. Thus, fuel was definitely reaching the carb. Perhaps the jets were somehow clogged. This did not seem plausible, as the bike had just died, all of the sudden. A clogged jet or such would have produced more gradual and progressive stumbling. I took the carb out anyhow, and gave it a once-over. Nothing of note was found, everything looked clean enough. I then reinstalled the carb and turned my eyes to the valves.

The valve clearances, at first, seemed to be quite ok, a tad on the loose side. However, I had great difficulties with the intake side. I simply could not get the clearances correct there. Thus, I decided to remove the cylinder head top section. Much to my horror, the following was found:













This would surely explain why the bike wouldn’t start. It also explains why the plug didn’t smell like gasoline. No combustion mix is able to enter the cylinder if the intake valves won’t even open.

The cam follower rollers are a known weak spot on the LC4. For this reason, I changed both of them last winter. It really frustrates me that the intake roller failed now, despite all the preventative maintenance I’ve tried to do. Many stories here and on other forums tell that the intake roller may seize and grind on the cam, but this type of damage, where the rocker arm itself and the cylinder head top section are damaged seems to be much rarer. My concern is also that where did all the needles from the roller and the corner of the rocker arm go, and more importantly, what kind of damage have they done while traveling through the engine internals?

This damage calls for a complete teardown of my engine. Everything should be fresh in my memory, as I’ve just finished rebuilding the ’98 LC4. I was certainly not planning anything this major for my bike during this winter. Ah, the joys of LC4 ownership…

Cheers,

Tseta
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Old 01-02-2011, 12:50 PM   #156
gunnerbuck
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Wow, sorry to see that!

I don't recall ever seeing a pic of the rocker roller carriage coming apart before... I wonder if the roller axle slid out and hung up to cause the breakage?

Hopefully that is the extent of the damage and lets hope the needles migrated to the drain magnets and no where else...
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Old 01-02-2011, 01:04 PM   #157
wrk2surf
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so will you be doing 3 or 4 motors this winter...

How did you peen the shafts last?

Did you drain your oil or pull the cylinder yet??
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Old 01-02-2011, 02:08 PM   #158
makazica
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Pffff....I really hoped it's something minor.....

I suppose you peened the shafts using a punch, but how many marks did you make? I did it that way on mine (twice) and on a friends bike with no problems. I went with 8 punchmarks....

I did, however, change the rollers this winter also as they seemed quite worn (surface wear, shafts were perfect)...which was strange as they were changed last winter.....

How do you explain the wear marked on the pic in the att.?

Anyway, I wish you a less stressful New year!

M.
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Old 01-02-2011, 09:21 PM   #159
Tseta OP
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Thanks for all the good wishes.

I will start diagnosing the engine more closely today. I will know much more once I pull the oil plugs and check under the clutch cover.

I changed both cam follower rollers last winter (Routine maintenance). I originally had peened the shafts with only 4 marks, but based on Gunnerbuck's advice, I went back and added 4 more punch marks, making it 8 dots total per side.

It seems that the peening in fact did not hold. The central shaft was able to slide out some, allowing it to flop around. This would explain the grooving in the middle of the shaft, and also the damage on the inside of the rocker cover. The roller must have also seized momentarily multiple times, perhaps this is the root cause of the damage. Once the shaft slid out far enough, it hung up under the cam bearing seat and through leverage action, broke off the mounting tab on the rocker arm. It must have been at this stage the engine finally quit working, as the effective valve clearances instantly became something in the magnitude of 10mm.



-T
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Old 01-02-2011, 10:44 PM   #160
wrk2surf
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http://cgi.ebay.com/ebaymotors/Camsh...Q5fAccessories
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Old 01-03-2011, 01:56 AM   #161
makazica
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Is there maybe another/different way to peen the shafts?

M.
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Old 01-03-2011, 02:48 AM   #162
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(This picture shows that a pen magnet soon filled up with swarf after swooshing it around in the oil drain pan...)




I opened up the clutch cover and...



... found "about" three of the needles at the bottom.

-----

wrk2srf: Thanks for the link. Once I figure out the extent of the damage, I will surely be looking at e-Bay for used parts. However, due to shipping and customs hassles, my searches will have to be limited to European sites.

Makazica: The factory does the peening with a "full-circle" profile tool, probably in a hydraulic press or such. The LC4 engine manual does not make a mention of the preferred peening method when replacing the rollers. I think that the factory-style tool could be made, but it could take a few iteration rounds to arrive at such a tool that produces adequate peens. This could be cost-prohibitive for most home mechanics. My opinion is that the center-punch method should be "good enough" and that I've now just ran into a case of bad luck...

Oh the drama...

Cheers,

Tseta
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Old 01-03-2011, 10:34 AM   #163
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So I lifted the engine out of the frame and onto the engine stand.



I took a closer look at the camshaft area and was able to pull those pieces. This is good news, sort of... I now have about 12 of the needles accounted for. I counted that a new intake roller has 16 needles. The corner of the roller mounting tab is almost a perfect fit onto the rocker arm. This means that it has not rattled around inside the engine for very long, and conversely, there isn't much metal flakes in circulation from that.

When I replaced the cam follower rollers last winter, the intake side was just about done (click here). The replacement now failed almost catastrophically...

I'm dreading the thought of opening up the engine, as some chipped teeth or loose bearings are bound to be found. It's always expensive to split the cases: "might as well change those as well, while I'm here...". On the other hand, I don't know if I'll be able to sleep soundly knowing one or two needles might still be knocking around in the cases.

Decisions, decisions...

-T
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Old 01-04-2011, 12:07 AM   #164
bmwktmbill
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Tseta,
Maybe the engine needs a kerosene enema(before you decide to split the cases).

What a 'frikkin' mess!!!!

My congratulations to the Finnish education system.
I am an English teacher by education(and a registered nurse).
bill
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Old 01-04-2011, 12:29 AM   #165
Luke
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Wow, that sucks. I did about the same thing and don't want to remember how much it cost. The first time I peened the shafts I put in divots a little bigger than yours- but they were centered at about the same distance from the edge of the shaft as the factory ring. The second time, I made the divots about 2mm in diameter - really pounded them, and they've held since.

I'd suggest that you pull the clutch and inspect the gears that are hidden by it. I had a chipped tooth on the little clutch basket gear which would have worn the oil pump gears out quickly if I'd left it. One of the kickstarter intermediate gears was also damaged. I also found a piece of the decompression cam in a hidden shelf above and to the right of the mainshaft. You can dig in with a magnet to get parts out of there. If they sit on the shelf for too long then they will be washed into the trasmission by the oil.
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