KTM LC4 (640) Thread Index

[theGrinch]

Originally Posted by CBR

Struggling to find the right info.
Chain and sprocket replacment time.

I currently have a 16/45 setup on the 2004 model 640 Enduro.
I would like to be able to switch between a 15/16/17 front sprockets and keep the 45 rear.

The thing is I am not sure how many links to leve in the chain. I have a 120 link ready to go . Any ideas?


If left to my own devices i will always stuff it up..hahaha

thanks

On my 99 LC4 I have 118 link with 16/45 and it looks like the 17 won't work, no more adjustment left.
I would try the the 120 and work my way down.

[CBR]

Originally Posted by CBR

Struggling to find the right info.
Chain and sprocket replacment time.

I currently have a 16/45 setup on the 2004 model 640 Enduro.
I would like to be able to switch between a 15/16/17 front sprockets and keep the 45 rear.

The thing is I am not sure how many links to leve in the chain. I have a 120 link ready to go . Any ideas?


If left to my own devices i will always stuff it up..hahaha

thanks

Well good plans gone by the wayside...lol..I know I would stuff it up

I know I had a 48 rear sprocket but something has made me think 45 for some reason...so I have a new 45 to put on the bike..I also have a 15 front but not sure if its a OEM KTM sprocket..The shoulder on the sprocket isnt as wide as the other 2 OEM sprockets...now Ill probably need to find a spacer or something..the smallest jobs end up turning into nightmares..

Havent got to the chain length yet..lol

[dirty_sanchez]

Originally Posted by CBR

Well good plans gone by the wayside...lol..I know I would stuff it up

I know I had a 48 rear sprocket but something has made me think 45 for some reason...so I have a new 45 to put on the bike..I also have a 15 front but not sure if its a OEM KTM sprocket..The shoulder on the sprocket isnt as wide as the other 2 OEM sprockets...now Ill probably need to find a spacer or something..the smallest jobs end up turning into nightmares..

Havent got to the chain length yet..lol

OEM fronts sprockets are strongly encouraged.

If you measure the thickness of an aftermarket and an OEM they are not the same. The thinner aftermarket front sprockets don't allow the countershaft shoulder nut to bring enough compression onto the sleeve and the countershaft O-Ring, which makes a seal, and it soon springs a slow leak.

Dirty

[Ricardo Kuhn]

The stupidest question ever.


What size socket wrench do I need for the sparkplug, I ask because a few weeks back we had the house painted and looks like the painters when away with a few more things than just paint cans, Including my socket for the KTM sparkplug along with all my other long sockets, three ratchets, etc

[meat popsicle]

Originally Posted by Ricardo Kuhn

The stupidest question ever.


What size socket wrench do I need for the sparkplug, I ask because a few weeks back we had the house painted and looks like the painters when away with a few more things than just paint cans, Including my socket for the KTM sparkplug along with all my other long sockets, three ratchets, etc

Dang... the socket for the spark plug on the LC4 needs to be "thin walled" as it is a tight recess. Not sure if one can be had on the open market that suits this problem - maybe check the KTM price to see how motivated you are to search.

[Ricardo Kuhn]

Originally Posted by meat popsicle

Dang... the socket for the spark plug on the LC4 needs to be "thin walled" as it is a tight recess. Not sure if one can be had on the open market that suits this problem - maybe check the KTM price to see how motivated you are to search.

Yeah tell me about it, I feel more sad about loosing that One than the rest of the other sockets and tools, Even if they where Snap on any everything.

So do you have any idea of the size, Maybe I can "Shave" a stock socket...?

Maybe I just wait until I get my new sparkplug, Then again I want to have the valves done by the time I get the new sparkplug

[meat popsicle]

Originally Posted by Ricardo Kuhn

Yeah tell me about it, I feel more sad about loosing that One than the rest of the other sockets and tools, Even if they where Snap on any everything.

So do you have any idea of the size, Maybe I can "Shave" a stock socket...?

Maybe I just wait until I get my new sparkplug, Then again I want to have the valves done by the time I get the new sparkplug

I've gots a link for ya: http://www.advrider.com/forums/showthread.php?t=132981 - lots of good, and not so good (but funny!) ideas in it.


Motion Pro might make one that works too.

[Ricardo Kuhn]

Originally Posted by meat popsicle

I've gots a link for ya: http://www.advrider.com/forums/showthread.php?t=132981 - lots of good, and not so good (but funny!) ideas in it.

Man end up been way more complicated than I realize, Thanks for the link..

Motion Pro might make one that works too.

I check them up, I bet they have it, If I was in San Francisco I just go to Scuderia and I'm sure they will have it in stock here in Salt lake city the KTM Dealer does not even sell 640's or 950 for that matter

[slackmeyer]

I've heard people talk about using a Yamaha plug wrench on a 950- which, as you know, has harder to reach sparkplugs than the 640. For my 640 enduro, a normal 5/8" plug socket, slightly ground down, works fine. It could be that the later Hi-flow heads have less room though.

[Ricardo Kuhn]

Originally Posted by meat popsicle

Motion Pro might make one that works too.

I got the 18mm Motion pro socket (Stock plug is 16mm) at the local "Motocross" shop and I also got a nice feeler gauge for less than $6 made by them too.

[Lortdadu]

For the rocker arm rollers, I've got an axial play of 0.30mm on both of the rollers, not the rocker arms. Should I change the rollers? There is no significant wear for the rollers on the outside, but in the manual it does say that no axial play should be on the rocker arm rollers. Also, the exhaust rocker arm has an axial play of 0.50mm, and the intake rocker arm has an axial play of 0.40mm, should I reshim these to the values of 0.20-0.30mm?

One final question, how the h*** do I get the rocker arm rollers out of the rocker arms?

I found the problem to my KTM not having enough power to rotate the engine here, the parts are worn, and especially the autodecomp system, it doesn't function the way it's supposed to.

[dirty_sanchez]

Originally Posted by Lortdadu

For the rocker arm rollers, I've got an axial play of 0.30mm on both of the rollers, not the rocker arms. Should I change the rollers? There is no significant wear for the rollers on the outside, but in the manual it does say that no axial play should be on the rocker arm rollers. Also, the exhaust rocker arm has an axial play of 0.50mm, and the intake rocker arm has an axial play of 0.40mm, should I reshim these to the values of 0.20-0.30mm?

One final question, how the h*** do I get the rocker arm rollers out of the rocker arms?

I found the problem to my KTM not having enough power to rotate the engine here, the parts are worn, and especially the autodecomp system, it doesn't function the way it's supposed to.

Lort- the rocker arm roller pins are pressed out. The pins the rocker arm rollers ride on have a history of wearing. When I replaced the exhaust side roller (the part of the exhaust rocker arm assy. which is actuated by the exhaust lobe of the cam) at 20k miles, the portion of the pin supported by 16 or 17 needle rollers was worn approximately 0.030". I used an old antique arbor press and a suitable socket slightly smaller in diameter than the pin and with some effort pushed right out. A bench vise likely won't have the strength to push these pins out.

Once you push the pin out and replace with new, you'll have to peen each end of this replacement pin to hold it in place.

When you mention axial play are you referring to the back and forth side to side movement, OR the movement/play/looseness between the inner diameter of the roller and the outer diameter of the pin?

If it's the side to side movement you mentioned, I wouldn't be overly concerned with that side slip movement.

Now the two rocker arm shafts must be properly shimmed.

One more word to the wise- If you're into the engine as deep as you appear to be replace part numbers 21 (Rocker Arm Shaft O-Rings) and #12 all 4 valve lash Adjustment screws. The wobble head on one of the Adjustment Screws on the intake side broke at 15k. Reference the "Engine" and "Valve Drive" page on a parts schematic for reference.

Dirty

[Lortdadu]

Yeah, I was planning on getting the shims. It's weird, I can only see 0.50mm and 1.00mm shims on the OEM fiche? I'm doing a good upgrade on it, so I'm gonna buy the bearings for the camshaft and the autodecmp spring as well. Also gonna Upgrade everything that I can open on the rocker arms. Meaning that I'm gonna upgrade the rollers, o-rings, adjustment screws...

I wanna be safe and sound for the first few hundred KM's at least.

Now that I read info about the LC4's, it seems more like a machine between a 2 and a 4 stroke, the maintenance intervals are pretty crazy! Thank god it's so easy to get my hands on different parts of the engine without having to remove the damn thing!

[dirty_sanchez]

Originally Posted by Lortdadu

Yeah, I was planning on getting the shims. It's weird, I can only see 0.50mm and 1.00mm shims on the OEM fiche? I'm doing a good upgrade on it, so I'm gonna buy the bearings for the camshaft and the autodecmp spring as well. Also gonna Upgrade everything that I can open on the rocker arms. Meaning that I'm gonna upgrade the rollers, o-rings, adjustment screws...

I wanna be safe and sound for the first few hundred KM's at least.

Now that I read info about the LC4's, it seems more like a machine between a 2 and a 4 stroke, the maintenance intervals are pretty crazy! Thank god it's so easy to get my hands on different parts of the engine without having to remove the damn thing!

As you shim the axial play on each rocker arm shaft make sure you position the wobble heads on the valve lash adjustment screws directly over the valve stems.

Unless you enjoy spending money, buy your bearings from a real industrial bearing business. You'll get better quality bearings at a lower price-same for the two bearings and seal if you happen to rebuild the water pump.

Dirty

[clintnz]

Originally Posted by Lortdadu

I'm gonna buy the bearings for the camshaft and the autodecmp spring as well. Also gonna Upgrade everything that I can open on the rocker arms. Meaning that I'm gonna upgrade the rollers, o-rings, adjustment screws...

Be aware this might not solve the starting problem - my decomp spring was still good, the decomp cam was ok, but the small pin in the camshaft that the decomp cam engages on was worn, this cannot be replaced easily, you may need either a good machine shop or a new cam.

This amount of wear made a big difference to ease of starting:



Re shimming the rockers, on mine I could move the rocker shafts in their bore a little for fine adjustment of the play before the cover is torqued down, tap them in with a tiny hammer, there is clearance around the bolts that locate them.

Cheers
Clint