duke 640 lc4

[bigalex40]

hi everybody

i am looking to buy a 640 lc4 year2002-03 and i would like to know more about this bike, good or bad


is it reliable

how much km have you done on yours

somethings to check when buying a used one?

what about the chain adjustment, is it well done?

i am 6,1 and 250lbs, will i feel like an elephant on a big wheel?

[bajadog]

I have an '02, enduro, and I have almost 11k miles.

Have taken my bike off road from San Diego to Cabo (60% off road),
twice now.

No major issues at all. Just keep up the valve adjustments, oil changes (synthetic ONLY).

If I had a choice between the '02 and '03, I would take the '03.
'03 and newer has the upgraded transmission roller bearing, and
the high flow head.

Here are some pointers to look for when you find a used bike:

Get down on hands and knees with a flashlight and look for leaks:
Beneath the countershaft sprocket.
Around the upper left corner of the head rocker cover.
Around the front left exhaust flange.
Around the head and base gasket area.
Around the kickstart/shift shaft area.

These are the most common leak locations for any LC4.

Look also for:

Weepy fork seals.
Leaky shock absorber.
Condition of brake pads and rotors.
Condition and tension of spokes.
Front/rear wheel/axle alignment.
Exhaust system cracks and leakage.
"If the air filter looks like a botany experiment gone awry, don't buy"
Fuel system leakage and signs of staining.
Condition of all rubber hoses... cracks and leakage.
"Vehicle alignment". Meaning... sit on the bike and look at bars, forks etc... does it all look straight to you?
Condition of the engine oil.
When you're on the bike, and you bounce up and down on the suspension... does it squeak and squawk or is it quiet and "fluid sounding".
Check that all hand controls and lighting work.
Check the adjustment and condition of the clutch cable, throttle and de-compression cables.
Check for headlight lens cracks... they are expensive lights.

When you start the bike, bear in mind that LC4s are noisy engines on a good day... but you shouldn't hear any "defined" loud noises, just a bunch of general muffled clicks and clacks.
Put a rag over the muffler with the engine runnning... the engine should have some noise, but not sound like it's eating itself alive.

Ask about valve lash adjustment frequency and if the owner has noticed any trends in valve recession or any surprise increases in lash.
Ask about oil and filter change frequency... at least every 3K miles or less is preferable.
Ask about steering head bearing service, rear suspension linkage service... and about water pump seal failure and repairs.
Does it have the recall front wheel? (This applies to '01 thru '03 only)

[bigalex40]

oh nice you are exactly the guy i'm looking for


thank you for your fast reply

can you tell me which years are these bike and what are the changes they made through the years. for better or worst also.

thanks


oh by the way i called a guy that had one for sale and he told me he had to change a bearing in the transmission, can you explain me this please. did they had a recall on this or is it a common problem of these bikes. and did they changed it over the years.

[bajadog]

Originally Posted by bigalex40

can you tell me which years are these bike and what are the changes they made through the years. for better or worst also.

thanks


oh by the way i called a guy that had one for sale and he told me he had to change a bearing in the transmission, can you explain me this please. did they had a recall on this or is it a common problem of these bikes. and did they changed it over the years.

The 03 and up 640 motor did not change.

The suspension on the certain '02s and up went to
48mm forks, from 43mm (I have 43mm and love them).

The transmission bearing is a topic of much debate.
It was said that in the Paris Dakar races, the 660 LC4 bikes in 1999
lost transmissions, because the output shaft bearing was a ball type
bearing.
This bearing was used up to 2002.

I did the upgrade myself to the newer roller bearing, but the
old bearing I pulled out looked fine.

There was no bearing recall.

On 2001 - 2003 640's, the front wheel had a spoke getting loose
issue. Some guys were getting flats as the spokes got loose, and
poked their tubes.
If you call KTM (440-985-3553) with your VIN number, they can tell you if the recall was done.
Some guys get brand new wheels. I just got spoke clamps to tie each pair
together.

[Dmitry]

I have 11K miles on my '01 SuMo LC4, just had to replace fork seals and last year re-sealed the rocker box, (couple hours of my time and few bucks in sealant and gaskets) This bike is my work horse!

My friends '00 Duke LC4 needed same rocker box service but he also replaced started clutch around 15K miles ($300 in parts)

Another one of my friends has '00 LC4E and he replaced the pitted cam at 30,000 miles, also same as above, rocker box leaked and starter clutch failed around 15K. Many sets of fork seals cause he rarely has front wheel on the ground.

If you looking at Duke (as title says) there is no spokes!

Best mod I ever put on the bike was a pumper carb.