KTM LC4 (640) Thread Index

[Lortdadu]

Originally Posted by Alik

Lort,

standard settings according to the manual:

MJ 147,5
Needle jet 689 X-6
Idling jet 45
Jet needle 6G5
Needle position 3rd from top + 1 mm
Mixture control screw open 2.25

Start from the standard setup and work it up one size a the time.
I would start with a 150 MJ and go no more than 152,5 MJ.
Also the standard needle postition for a 400 seems to be different than normal 640 setup which is on 3rd clip. There seems to be an additional 1mm washer involeved.
Turn down the mixture control to stock setup. And start to reasses the transition effect by turning it about ¼ increments at the time.

I think You should better post in the BST-40 Bible thread. you will find some more geeks lurking there ;)

Alright, thanks. I'll try those, and post more in the BST-40 Bible thread if I need any more help! :)

[TaxMan]

Originally Posted by Tonicu

500 kms. done after my rocker bearings and camshaft change, the engine seems to be back in good shape. However, I've noticed that when ridden quite hard at steepy&narrow slow enduro tracks the stripes on the panel go quickly up from the 2 or 3 to five, then the fan kicks in. Everything normal so far, but when at those five stripes, it expulses some coolant through the cap hose that goes to the chasis. I thought it'd be a mere question of too much coolant added after fixing the cam&timing gear, but it apparently isn't the case. Maybe some air got in?
What temperature - how many stripes - do you normally see in your panel both running smoothly and as if you'd had stolen it?

This sounds like mine. Riding in traffic after a stretch on the freeway would bring the temp up and would also cause some coolant belching. Never overflowed but made a mess and caused billows of steam on occasion. Got tired of it spitting and was worried about running low on coolant out in the sticks of NV. After reading a thread somewhere in the Index, i added a coolant recover tank here: http://rlrproducts.com/. Perfect fix, no problems since install and no worries about losing fluid today that I need tomorrow.

[Sumi]

Originally Posted by TaxMan

This sounds like mine. Riding in traffic after a stretch on the freeway would bring the temp up and would also cause some coolant belching. Never overflowed but made a mess and caused billows of steam on occasion. Got tired of it spitting and was worried about running low on coolant out in the sticks of NV. After reading a thread somewhere in the Index, i added a coolant recover tank here: http://rlrproducts.com/. Perfect fix, no problems since install and no worries about losing fluid today that I need tomorrow.

I've also had this problem.. Turned out that the radiator cap wasn't holding the pressure well.. A new cap solved the problem:)

[Tonicu]

Originally Posted by TaxMan

This sounds like mine. Riding in traffic after a stretch on the freeway would bring the temp up and would also cause some coolant belching. Never overflowed but made a mess and caused billows of steam on occasion. Got tired of it spitting and was worried about running low on coolant out in the sticks of NV. After reading a thread somewhere in the Index, i added a coolant recover tank here: http://rlrproducts.com/. Perfect fix, no problems since install and no worries about losing fluid today that I need tomorrow.

I thought too about adding a coolant recover tank, but after riding the bike a bit more it seems the cause was an overfilled radiator.
This sorted out, a couple more things are annoying me. The first one is that sometimes it seems I'm running out of fuel - but I'm not - and even the engine comes to a stop. It takes a while to restart it, and then the problem disappears ... until it comes again out of the blue. I haven't found time to check the fuel filter; I also thought I may have an air intake somewhere, but as I don't have any other symptoms it's not the most likely option. Any ideas or do I take the carb out see if there's a frog inside misbehaving?
The second issue : could be the sprag clutch, but let's listen to what you experts opinion is. The engine starts fine, always fine when cold, at the first touch of the button. But when hot, about 30% of the times, it suddenly seems the starter motor finds it's too hard to turn the engine, until it passes TDC and it finally the engine starts. The starter motor is in good shape, so is the battery and the sprag clutch doesn't make any weird noise at all. To my unexperienced ear, that is.
Otherwise, great fun! Fitted a pair of Continental TKC 80 and although for just enduro use or mud there are (far) better options that last 5 times less, I think they indeed are a good allround tyre, easy to control, fun to drive and more important, that inspires a lot of confidence, both on dirt and tarmac. We'll see how much they last, the rear has only 500 kms. of dirt use and wear is quite noticeable. However, the front one still looks brand new.

[Sumi]

Originally Posted by Tonicu

The second issue : could be the sprag clutch, but let's listen to what you experts opinion is. The engine starts fine, always fine when cold, at the first touch of the button. But when hot, about 30% of the times, it suddenly seems the starter motor finds it's too hard to turn the engine, until it passes TDC and it finally the engine starts. The starter motor is in good shape, so is the battery and the sprag clutch doesn't make any weird noise at all. To my unexperienced ear, that is.

They all do that:) It's even mentioned in the owners manual. Give it a little help with the manual decompressor, and thats it:)

[Tonicu]

Cheers!
I have to replace the decomp lever cable. Now I can't remember which end goes which way ...
Anyhow, if even with my mechanical idiocy I was able to change the camshaft, rocker bearings and rebuild the water pump I should be able to find out what goes where. ;)

[Low594]

Originally Posted by Tonicu

500 kms. done after my rocker bearings and camshaft change, the engine seems to be back in good shape. However, I've noticed that when ridden quite hard at steepy&narrow slow enduro tracks the stripes on the panel go quickly up from the 2 or 3 to five, then the fan kicks in. Everything normal so far, but when at those five stripes, it expulses some coolant through the cap hose that goes to the chasis. I thought it'd be a mere question of too much coolant added after fixing the cam&timing gear, but it apparently isn't the case. Maybe some air got in?
What temperature - how many stripes - do you normally see in your panel both running smoothly and as if you'd had stolen it?

I wrestled with mine blowing coolant, but without overheating, til it was very empty. Turns out 3 of the 4 head bolts were stripped out and the compression was blowing past the head gasket and over pressurizing the radiator! There has been an upgrade in radiator cap pressure since mine was built, not sure when it was updated tho. Thinking of adding that nice overflow tank tho!

[Thumper996]

I simply added an after market overflow tank last year. We run the same setup on our off road dirt bikes, nah sayers will comment that this will mess up the radiator or fins, but after years and years of having these on dirt bikes i have yet to have an issue mounting it directly to the radiator with the provided zip ties through the radiator fins.

[Lortdadu]

Those overflow tanks look nice. How well do they fit with the tank on?

[Pistolero]

I have a 2000 640 Enduro and the previous owner trimmed the bars for woods riding. I personally don't like the narrow bars because I ride on the street more. but I would prefer if I could replace the bars with a stock replacement if available because I have hand guards on it already and I don't want to have to buy more..

I was wondering if the stock handlebars part number 58302001400 are 1-1/8... the bars on my bike are sort of a off silver color and of course say KTM on them... I don't mean to be captain obvious ... just want you guys to know what I'm talking about.

Thanks and advance!

[MNCherryinCA]

Originally Posted by Pistolero

I have a 2000 640 Enduro and the previous owner trimmed the bars for woods riding. I personally don't like the narrow bars because I ride on the street more. but I would prefer if I could replace the bars with a stock replacement if available because I have hand guards on it already and I don't want to have to buy more..

I was wondering if the stock handlebars part number 58302001400 are 1-1/8... the bars on my bike are sort of a off silver color and of course say KTM on them... I don't mean to be captain obvious ... just want you guys to know what I'm talking about.

Thanks and advance!

i have stock bars off my 04 625 SXC that I don't use anymore. They are tapered from 1 1/8 in the middle to about 7/8 on the outside. if interested, PM me. I can let them go cheap.

[christian]

Originally Posted by MNCherryinCA

i have stock bars off my 04 625 SXC that I don't use anymore. They are tapered from 1 1/8 in the middle to about 7/8 on the outside. if interested, PM me. I can let them go cheap.

My 2000 had 7/8 bar all the way

If he does take the 1-1/8 I maybe interested in them

[Pistolero]

Originally Posted by christian

My 2000 had 7/8 bar all the way

If he does take the 1-1/8 I maybe interested in them

That's what I was afraid of. I have heard several people tell me theirs came with 7/8.

I'm pretty sure I'll grab those bars if the price is right but I'm sure he will let you know if I pass

Thanks for the feedback guys!

[slackmeyer]

Those SXC bars are a nice bend, IMHO. Maybe a bit low without risers, though.

If your bar clamps are 7/8", it's pretty easy to get fatbar clamps off of the many other KTMs that use them- my 99 LC4-E came with 7/8" clamps, I got some clamps from a 250-EXC.

[Pistolero]

Originally Posted by slackmeyer

Those SXC bars are a nice bend, IMHO. Maybe a bit low without risers, though.

If your bar clamps are 7/8", it's pretty easy to get fatbar clamps off of the many other KTMs that use them- my 99 LC4-E came with 7/8" clamps, I got some clamps from a 250-EXC.

My bike has 1-1/8 clamps with 2" 1-1/8 rox risers.. what I'm worried about is my hand guards fitting the different bars