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Old 8 Jul 2008
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Thumbs up My first impression on the Adv 640 2004


I have a day off in Mongolia after seven days of riding and thought I'd post my impressions on the bike. I bought the bike with about 13000km six weeks before leaving for Mongolia. I have put on all kinds of after market stuff.

The bike handles great after one gets used to the high point of gravity (with luggage). Very good suspension also. Saved my as when I hit a 50cm high wall of gravel in the desert which made the bike jump a couple of meters :-)

This is probably the best bike for Mongolia I think.

However two things I am not very happy with that KTM is responsible for:

1. Lower front fender. I got off the main track a few days ago and got on a track with some muddy sections. The mongolian mud is more like clay, and will clog the tire and the fender. After some minutes (probably because of the heat from the sun and from the tires) it dries and after not to long the front wheel locks up and off you go :-( I tried to take the fender off, but there is a brake line that goes from one side of the wheel to the other side, so it wasn't possible. Therefore I had to stop every ten minutes to clear the mud from the tires and under the fender so that the front wheel woudn't lock up.

How do you deal with this problem? Some kind of modification to the fender and brake line?

2. Front rim. I have had the front tire pressure at 18-22 psi and the other day after riding a road with a lot of potholes (speed was 50-70kmph) I discovered that the edge of the front rim had bent a bit. Nothing seriously. But rather disappointing, since that has never happened on my previous bike (the old F650) running much higher speeds at similar roads with same tire pressure. I travelled 2004 in Iceland with a guy from Belgium and he had a new 950 adv and this happened to him also. Though he was riding much higher speed at that time (100kmph) so the rim was bent a bit more. I have now put in some more air and will be running the front at 22 psi just as i do with the rear (which hasn't had any problems).

Somewhere I have read that some people have gotten a new front rim from warranty, was that for the 640 Adv 2004 model?

How do you deal with this problem? Higher tire pressure?

Two other things I am not happy with, but can only be blamed on the previous owners:

1. The jetting is to rich for the high altitude in Mongolia 1500-2500m. The bike has had the snorkel removed. The sommer needle and jets installed. And an aftermarket exhaust put on (XRacing?). The bike was (I think) running a bit on the rich side back home at sea level. ANyway I droped the needle down a notch and trimmed the mixture and got the fuel consumption down from 8 litres to about 6 litres for 100km. The bike runs ok at lower rpms, but stil bad on high rpms. I guess I should change to smaller jets to get it right. When I get back home I'll fiddle more with this. Rather have a bike that consumes less fuel and is quieter, then a bike that has a few more hp and is very loud (it's loud even with helmet and earplugs...)

2. I had to rebuild the engine before I left because there was a problem with some components of the electric starter. The first owner put in a racing cam (G1?) and removed the autodecomp a few years ago. Trying to start the bike not using the manual decomp has (or perhaps even using that???) has ruined some part of the electric starter mechanism. The cam chain was also very worn for a bike with so little milage. Now I opnly yse the kickstart which is just fine. I am thinking of changing back the engine to original when i get back home (removing the race cam and install a auto decomp).

Anyhow a great bike for off road riding :-)
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Old 8 Jul 2008
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A couple of thoughts:

1. Electric starter - before you assume the problem is caused by the lack of auto-decompression, make sure you check the starter clutch, which is located behind the flywheel. The problem is that the spring in the starter clutch becomes loose. On a 2000 Adv I have had to replace this part twice after the electric starter failed and I got sick of kicking. Adv Rider has a write up on how to repair this without actually replacing it. Otherwise you will probably just need to buy this KTM part;

58440026000 FREE-WHEEL FWD 332008 BLS

LC4 640 starter clutch fix - ADVrider

2. Low fender - I think KTMs rationale is that in sand a low fender wont clog, but clearly in muddy conditions it is an issue. Changing to a high fender will most likely involve converting to a single disc. Again there is lots of detailed info on Adv Rider on the conversion.

KTM LC4 (640) Thread Index - ADVrider (This is the index page - scroll down to 3c and there are half a dozen threads on the conversion)

3. Behr Rims - I assume you have a stock Behr rim on an 04 Adv? Apparently there have been all sorts of problems with the front rim bending. Might want to upgrade it to an Excel rim. There was a recall on some front rims, but I am not sure if it affected the 04s as well.

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Old 12 Jul 2008
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Hi Matt.

I am back in the Internet zone :-)

I got the bike back 4 days before the departure from the mechanic, so I haven't dug any deeper in to the cause, but will do that when I get back. He showed my a part that was damaged. I have the partnumber back home on a papper and will post that when I get back. I'll read a little more on the advrider site also about your tip.

Yeah it's behr rims and after some more days of riding - plenty of minor dents in the edge of the rim. In other words - they really suck!!! KTM should be ashamed. (probably some designer that made some miscalculations after a hard night out :-)

I'll check in to the fender mod when I get back home. In Sweden I wouldn't need it, since I don't ride the KTM in mud. That's left for my Husaberg :-)

Greatings from Ulan Bator!
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Old 29 Jul 2008
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Hi Spakur,

I had exactly the same problem as you with the front fender back in 2006 (Venäjä - Mongolia 2.7. - 30.8.2006). Fortunately we were stuck in the mud only for a day so what I did was to remove the fender altogether. Unfortunately I don't have a picture of that but if I remember correctly what I noticed that only problem was that brake line which went to the cylinder on the right side and that cable I secured with some line so that there was enough slack for suspension but not so much the line to get stuck by the tyre. Before the trip I had made raisers for the fender but never got to install them and I did not want to have the fully raised version because of those long and windy roads of Russia.

And for the too rich mixture go for the smaller main jet.

Enjoy your tour!
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Old 30 Jul 2008
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I read somewhere that the new LC8 adventures have the low fender mounted a bit higher to help with mud. Might want to look into that.

Alternatively you could just get a €20 standard high mount fender, you will easily get twice that for your low mounted one on Ebay.
Currently on a RTW ride:
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Old 3 Aug 2008
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Thanks for the tip Lukas!

I'll look in to it when I get back to Sweden in 2 weeks.
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Old 3 Aug 2008
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Originally Posted by LukasM View Post
Alternatively you could just get a €20 standard high mount fender, you will easily get twice that for your low mounted one on Ebay.
Yes, and if you are worried about the brake lines, you could just run two separate lines from the master cylinder (double banjo bolt), one down each leg? - Goodrich braided etc.

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