Lord help me, I just bought a basket case LC4

[slackmeyer]

I couldn't pass it up. Somethin's wrong in the engine- the piston hits the sparkplug, nobody knows anything else. Otherwise a decent 640e, 16k miles, two sets of wheels, bill mayer seat, for a grand.

I suspect that the main bearing behind the clutch basket has disintegrated, or the conrod is stretched/broken. I just got it tonight, I'll start taking things apart in the next week or so. This is meant to be a winter project, so no big hurry.

Guess I better start taking pictures, huh.

zak

 

[little_twin]

I'm pretty sure KTM's eat up bottom end bearings. Thant is more than likely the problem.

 

[wsmc831]

I think it's common in the pre 04 models. Should find plenty of info about it on ktmtalk.

 

[slackmeyer]

I think it's common in the pre 04 models. Should find plenty of info about it on ktmtalk.

Yeah, that's what I read. But I don't want to jump to conclusions before I take out the clutch and look for myself. And I still don't know how much damage that bearing could have caused.

Zak

 

[slackmeyer]

Yeah, that's what I read. But I don't want to jump to conclusions before I take out the clutch and look for myself. And I still don't know how much damage that bearing could have caused.

Zak

Ok, I jumped to a conclusion too soon- the mainshaft bearing is fine, the bottom end is fine, and I think this has something to do with the problem:

The piston went kablooey. The head doesn't look so hot either, but it may be cleaned up and put back into service until I find a good used one:

(there are pockmarks on the aluminum, but the valves and seats look just fine).
Of course the cylinder is damaged, even thought the little nicks and scratches don't show up on the photos. It's a nikasil coated aluminum bore, I'm going to ask around about having it overbored for the rallye 660 piston, or sleeved and bored for a new 640 piston. Looks like they changed from cast pistons to forged pistons in 2003- I wonder why. I've got a friend that's done this exact same repair, so it was in the back of my mind as a possibility.

Oh, and the bent sparkplug was a result of engine shrapnel, not of the piston hitting it.

zak

 

[boney]

zak, what year is it? The 02 and older LC4 have a ball bearing behind the clutch. If you have that, you should upgrade it to a roller bearing that the 03 and later came with. It's a straight swap, but you need to be creative about getting it out without cracking the case. There was a travelling tool kit on KTM Talk a few years ago when I did mine. Look for specifics there.

Look up Luke on ADVRider. He just did a re-build and piston swap on his LC4. He may have some useful information. I think he had the cylinder re-coated too.

 

[slackmeyer]

Thanks boney- I'll PM luke about the cylinder recoating. It's a 99 or 2000- the title says 2000. It still has the ball bearing on the mainshaft behind the clutch, and I'm planning to put in the roller bearing, but that's not what caused the problems.

zak

 

[Calikatoom]

Hi Zak,

This is Gail, the previous owner of the LC4. I'd love to stay in the loop on the repair side of things. Since this began, I have wondered if I overlooked any maintenance issues. I knew about the crank bearing issue, but was told by a dealer that the 2000 models specifically were not affected.? That piston looks bad! I'd hate to think this was caused by anything I failed to do to the bike.

Anyway, I LOVED that bike! I have owned two LC4E bikes and put aprox 10K on each.

If you have any questions about the bike's history, feel free to email me at sales@cyclespecialties.com. I don't check BARF tooooo often.

Good luck with the repairs!

Gail Weaver

 

[GetaGripGreg]

I was inside the 640 from my '01 Duke II last year. It had a failed big end bearing at about 15 K Miles. My piston was fine and I reused it, didn't even change the ring.

You should seriously consider replacing the crank at your mileage, if you're doing the top end. For SURE if you are going up in bore size.

You also want to replace the mainshaft bearing, and while your at it, replace the spring on the starter sprag clutch (mine is apart for that now).

Check the water pump shaft and seals.

Nothing else in my motor showed any wear. I only replaced the crank bearings and rebuilt it with a rod kit (and all seals and gaskets). Still totaled $500 in parts.

ADV is your friend:
http://www.advrider.com/forums/showthread.php?t=86958

Also KTMtalk
http://ktmtalk.com/index.php?showforum=8

Cheers,
Greg

 

[Ironbutt]

Let me know if you need a arbor press to get the cases apart or any other shop tools.. or a place to rebuild it at..

 

[slackmeyer]

Thanks Greg and Ironbutt!
I still haven't sent off the cylinder yet (right now I need to fix the waterpump on my 950), but the more I read, the more I think that I should do some preventative repair on the bottom end. I've heard a couple stories about the big end bearing going out, and I'm also at about 15,000 miles on this bike.

Zak

 

[Ironbutt]

Thanks Greg and Ironbutt!
I still haven't sent off the cylinder yet (right now I need to fix the waterpump on my 950), but the more I read, the more I think that I should do some preventative repair on the bottom end. I've heard a couple stories about the big end bearing going out, and I'm also at about 15,000 miles on this bike.

Zak

I find it hard to believe that at 15k these motor's come apart.. You sure this isn't a Harley Davidson your working on? :laughing

 

[boney]

I find it hard to believe that at 15k these motor's come apart.. You sure this isn't a Harley Davidson your working on? :laughing

God I hope not. That means I'm gonna be due for a rebuild soon. :wow

 

[slackmeyer]

I find it hard to believe that at 15k these motor's come apart.. You sure this isn't a Harley Davidson your working on? :laughing

That's true, I've heard many stories of high mileage 640s with no bottom end work. I've also heard of a couple 640s with a rod knock at this mileage, and considering the stress that crunching up chunks of piston could put on the bottom end. . . well, I'll at least have someone with a bit more experience look at it. I think I'm going to take the head up to EDCO in Petaluma to get cleaned up, I may drag the whole motor up there, see if he'll give it a once over.

I'd love to just put this back together, but I'd also like to not take it apart again for 20k.

As far as the piston goes, I'd think about replacing any cast piston (pre 2002 bikes, I think) with a forged one (stock or wossner), if you really depended on your bike getting you home. But that's just based on anecdotal evidence at this point.

zak

zak

 

[SuperMike]

I was registered at your forum. I have printed the test message. Do not delete, please.
Just wanted to say thanks to everyone for the warm/scary welcome,I'm really looking forward to talk about anything and everything horror related.

:wtf

 

[slackmeyer]

Uhhm, back to our original topic-
cylinder sent off to L.A. Sleeve, so I won't be doing much on the bike until the cylinder, piston, and gaskets get back to me. Probably a good time to get the updated main shaft bearing and put it in. . . we'll see if I get around to it.

Hey, this is a winter project, so I've got to stretch it out over the whole winter, right? (Even if it could be done in a couple weekends)

zak

 

[brichter]

:wtf

Spammer, check sig...

 

[SuperMike]

Spammer, check sig...

I know! But posting HERE?!? It just doesn't make sense! :laughing

 

[brichter]

Spammers aren't interested in the subject of the thread they post in, it may even be automated.

 

[slackmeyer]

Allllllllll righty then. Time to get this thread back on track- I finally have all the parts I need mostly, and the time to start puttin them together:

(Parts and the bike with a hole in it).

Last night I lapped the valves very lightly, put on new valve stem seals, and scraped off all the old gasket residue from the head, cylinder, and engine. Managed to cut my thumb pretty good while doing it, too.

The head still shows scars from it's close encounters of the piston kind, but the valves were in great shape- 30 seconds of lapping left a nice polished valve and seat. :thumbup

Wossner forged piston replacing the KTM cast one:

Nicely honed cast iron sleeve, from LA Sleeve:

Piston in cylinder, base gasket coated with hondabond, and it's time to retrieve the wrist pin from the freezer (where I put it last night).

Everything's coming together:

Tighten down the cylinder nuts:

No room to get a torque wrench in there, so calibrated my brain before tightening:

Check that all the TDC indicators are where they should be:

And put on the head gasket and head:

I put in the cam and cam bearings too, but I need to double check timing before those are in there permanently. Next up, rebuilding the water pump, and then installing that and the rocker cover.

zak