'02 mainshaft bearing

**neil.larsen** · #1 20 Apr 2005

I gather that the gearbox mainshaft bearing on the '02 640 engine is weak...anybody out there changed theirs?
What are the symptoms of the bearing breaking up? My clutch has been noisy since I bought the bike, several thousand miles ago.
Is it possible to replace this bearing without splitting the crackcase halves, or is a full strip necessary?
In which case, any other mods worth doing to improve the '02 engine?

thanks in advance
Neil

**Ian** · #2 20 Apr 2005

I just had the bearing replaced on my 2002 640LC4. I was very lucky - the inner part of the bearing that holds the balls in had started to come apart and the balls were damaged - the stray bits were recovered fortunately. The bike has about 13000 miles on it, although I don't know if mileage makes a difference.

I had the replacement done as a precautionary measure - there were not untoward noises before. Both LC4s I've had have been noisy with the clutch engaged.

It was done by Swampy at Marsh Performance in Saltash (01752 844456) - he didn't need to do a full rebuild.

The only other mods I've done to the engine unit itself are to fit clutch springs from a rally bike. I've also fitted the KTM open airbox door (this might be undone if it increases fuel consumption too much), a replacement silencer (Akrapovic slip-on, but I think the SXC version is also worthwhile) and the dual-curve ignition box.

**miles murray** · #3 20 Apr 2005

Check out this thread on advrider.com
http://www.advrider.com/forums/showt...ht=KTM+bearing

it gives a great 'how to' on changing the bearing - pics and all.

**neil.larsen** · #4 21 Apr 2005

Thanks, Ian -
I'll have a peek behind the clutch soon - I'm on a very similar milage to that, so a good precaution, I reckon. Will give Swampy a ring too, thanks for the details.

**neil.larsen** · #5 21 Apr 2005

Excellent link - always helpful to let other people find the problems before doing a job yourself!
Thanks v much -
I'll at least have a quick look in there soon, just to put my mind at rest.

Neil

**neil.larsen** · #6 23 Apr 2005

Well, surprise, surprise, around 10k miles and the mainsaft bearing has about one mm of radial play! Completely shot bearing, but not yet dropping bits into the gearbox. Time to make a bearing puller I think.
Strongly recommend other '02 owners to have a look - only takes 15 minutes or so to get to it.

**Tommo** · #7 27 Apr 2005

Neil..

I had mine changed by swampy marsh in Plymouth, he reckons he can do in in 20 minutes without spilling any oil if necessary. I had mine done along with a full service and a change of fork seals and it cost me £200 all in....a lot easier than making tools..:-)

**neil.larsen** · #8 28 Apr 2005

Follow up -
If you have an '02 check your bearing - mine was definitely unwell at less than 10k miles. The clutch rattle it's had since I bought it has now gone (or at least become a lot quieter)

Total cost £43. Doesn't take much time, once you have a puller.
The advrider link is very good, but to add to it...
Lie the bike (almost) on its side - then you dont spill any/much oil.
Use plenty of protection to minimise the metal filings getting in the engine. Rags with grease on are good - the stuff sticks to the grease.
I left a magnet just beneath where I was working to try and catch some more..
Best tool I found to use in a Dremel is a small ball nosed burr.
I will change the oil & filters very soon - wish I'd done the fix BEFORE my recent oilchange.

Doesn't take long, doesn't cost much - you know it makes sense.

Thanks to all for your help

If anybody needs a pulletr, let me know, I hope I'll never need it again!

Cheers
Neil