Thanks, good info there

Its a bit of detective work, I like to start with the easy stuff first and tick them off the check list before going more in depth and pulling the top end.

Once you get everything set up properly the 03 + 640s will go quite a while between top end service intervals...

Happy New Year :)

Well here's a quick update as I got the bike back:

Compression test - all good

Throttle Position Sensor - was apparently miles out, now adjusted (was showing that the throttle was wide open when in fact it was closed)

Timing - all ok

Carb - opened up and checked, very clean and nothing untoward noted, some minor adjustments made.

Air filter - despite claims from the previous KTM guy (see below) that this was cleaned, the filter was actually deteriorating and I suspect some of this had gotten into the carb earlier

SM Motech side stand fitted - damn that thing is fierce! But it works well and there's no danger of ever riding off with it down haha

Radiator - had used a little bit of fluid, guess this went out the overflow as no leaks noted

Backfiring/popping - apparently its doing this less now and only in low gears


Only got it back last night but my initial thoughts was it was going better so will try to get out on it over the next week to so see what has improved and will also check on the fuel economy.

Another issue that popped up recently (actually when I plugged in a USB adapter for charging my phone) was that the instrument cluster display got 'weaker' (now its hard to read) and the clock (time) disappeared - any thoughts?

Have you wired your USB into the clock loom ??

There's a standard accessory socket on the front panel

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If your lights are dimming its due to voltage drop. Due to a drain which the circuit can't support or a bad earth. Try it with the engine running.

Some USB devices can perhaps pull more juice than KTM intended.

I'm not sure it's that. This happened when it was plugged that one time and ever since even when nothing is plugged in.

The time display disappearing is just weird too, I mean why not the odometer or trip readings too as they all display in the same part of the screen

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Gremlins. You need an exorcist.

My money's on aliens

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If it is doing this permanently rather than intermittantly, then possibly age related.
Car instrument panels can show similar symptoms; IIRC, some Nissans had a habit of losing the digital clock display or parts of the electronic numeral display(s).

TPS? Wow, forget your bike had one! Hope it's the source of the problem!

IIRC, KTM instrument clusters are KNOWN to go bad for no obvious reason. So you may be on the hook for a new one and I believe they are very expensive.
:(

If you remove it ... you risk messing with wiring and screwing up CDI as a lot of the wiring goes through the CDI, so I'm not sure you can just unplug it and throw it in the bin ... but there may be a way, if you know how.

If the cluster has gotten WET ... you may try drying it slowly in the Sun (FACE DOWN!) for couple days. Never face LED display directly into Sun ... this will ruin it for sure ... and that could be what's happened to yours. :oops2:

Good Luck! :D

yeah, but it can't be a coincidence that both things (screen fade / disappearing clock) happened at same time as using the accessory power socket for the first time. I read somewhere that a fuse could have gone or that there might even be a watch battery somewhere on the cluster for the clock but not convinced has haven't seen anything in the manual about that. Will check the fuses though.

Incidentally the clock DOES reappear if I hold both the Mode and Set buttons while ignition off, then turn on again. I can reset the clock and it works fine while I'm riding but it goes away again next time I turn off lol.

It's definitely running better, much more lively than it was. Will keep monitoring and will check what the fuel consumption is doing. Hoping it was just a combination of all these things plus $hitty maintenance from the previous owner (not forgetting the incompetent work from the KTM mechanic..)

[QUOTE=mollydog;525951]TPS? Wow, forget your bike had one! Hope it's the source of the problem!]

The early technology used in digital displays is possibly at the heart of the issue.
+ you don't know the history of the machine - for instance, water entering the display could have short circuited some of the electronic "mother board".

Certainly, we are talking herein about electronics, not electrickery.
Computer mother boards have built in "button batteries" (that maintain memory functions while not powered up by any other means) and modern CANbus machines that have ECUs may also contain such technology; I doubt that the 640 has this and your handbook doesn't mention such?

I had a 2008 990 that has the same "Tonka toy orange" display and never had issues with that; I also had a 2003 Nissan car which had part of the digital display missing especially within the clock digits; some of the latter worked and some did not. There were other things of more importance however.

Well clock issue is formally resolved - found 2 blown 10A fuses (no 2 & 5). Works fine now :) - all fuses were checked a while ago though so guess something blew when the accessory socket was used

I took the opportunity to check the sprocket sizes today as have been meaning to make sure they are standard - but interestingly they're actually 40T / 16T. The rear should be 42T right? Its not in great condition (the front is totally fine though..) so will replace with a 42. Any ideas how the 40/16 combo would affect the performance?

You need to check the tech specs for the original information for the bike.

A bigger number of teeth at the back will lower the gearing overall, for increased acceleration and lower top speed, all else remaining the same.
Your existing combination is vice versa.

Great news on the dash display! :thumbup1: Easy, simple fix!

I'd look up standard sprocket sizes and go with that to start. 16T front sprocket seems BIG to me. If you cruise highway over 70 mph a lot then maybe OK, but for general riding, light trail riding, lower gearing will feel stronger with crisper acceleration.

15T/42T may be the way to go. Remember, one T change at front equals "around" 3 T at the rear. So sounds like your bike was geared quite HIGH.

Less vibes may be why PO did this, as your bike has some of the worst vibes of any bike I've ever owned (over 50) ... although my Duke ll was really not bad. (Man, wish I'd not sold that one! doh)

KTM rep said the Duke's dual exhaust calms vibes. No idea how he came up with that. But compared to my 640 dual sport, the Duke felt like a Lexus.
bier

If replacing fuses brings the clock back then you likely have a short in the system... Most likely areas to check are the cluster wrap harness of wires that are zip tied to the dash support bar and the wires that run to to the accessory outlet... Check the wires where they bend as they come out of the harness for abrasions to the shielding and check that they have not rubbed raw against the dash bar... Check the wires for the same where they go to the cluster plugs on the right side dash support strut... Another thing to check is the soldered terminals inside the ignition keyswitch as they will sometimes pop loose and cause erratic electrical problems.. To get at the keyswitch you have to remove the base by taking out the 2 phillips head screws and then pry and pop the base apart as it is a slip fit plastic sleeve.. Once apart you will be able to see if any terminals are broken and resolder them back to their posts...

I still have all the original electrical components on my bike at 210,000+ km but have had to fix worn wires and such on several occasions... Sometimes the buttons stop working on the speedo.. When that happens I remove the faceplate and spray electro contact cleaner in at the same time working the buttons, this bit of a wash always restores the function of the buttons..

16/42 with a 110 link chain is the OEM standard gearing for this bike and works well for all around riding... A lot of guys that do a bit more technical riding will go with the 15/42 that Mollydog mentioned... As KTM uses flip around axle adjuster blocks you can drop 2 teeth on the countershaft or rear sprocket without having to shorten the chain... A word of warning, do not buy the OEM aluminum sprockets, they are crap and last about 7000 KM... Instead ask for the KTM steel sprockets which last 3 times longer or go with aftermarket steel sprockets...

I run 17/45 or 17/44 on my bikes which is close to stock gearing but allows a slightly bigger bend radius to the chain giving it a little longer lifespan.. With the bigger bend radius the chain also rubs a slight bit less on the rub block so that lasts longer too... This gearing requires a 112 link chain... I run this gearing all the time for all types of riding, in the real tight tough stuff slipping the clutch is my low gear...

That is good strategy to extend chain/sprocket and rubbing block life! :thumbup1:

On some bikes its hard to go with a BIG front sprocket because of clearance issues. (DR650) I can go up ONE T but no more. Going to a tiny front sprocket to achieve lower gearing also has it's problems (i.e. rapid front sprocket wear, rubbing block wear)

The beauty of your set up is if you get into technical conditions you can simply pull over the put on a 15T front sprocket. 10 minutes later you've got Mountain Goat low gearing! bier

Quality aftermarket sprockets are the way to go to save a few bucks.
JT sprockets (Thailand) are pretty good in my experience, nearly as good as OEM. As said, Steel only!

Just thought I'd post a little update seeing as we seem to have resolved the issues now.

My mechanic friend believes that the KTM workshop opened up the head, replaced the 2 intake valves, realised they didn't know what they were doing, stuck everything back together (without replacing the head gasket), wrongly set the timing chain and the valve adjustment. Also the throttle position sensor was a mile out set in the complete opposite setting.

Long story short, we had to replace the head gasket as there was signs of radiator water getting into the head. Whilst it was opened, we overhauled the water pump but all the rockers and cam follower bearings etc were fine, no play at all :)

So the list of work done would be something like the following:
Chain/sprocket replacement
New air filter (old one was actually disintegrating)
Fork seals
Throttle position sensor adjust
Top end overhaul and gasket
Compression test - all good
Intake valves replaced
Water pump overhaul
New radiator fan (bearings were seizing, not 'cool' in Malaysian temps..it's now wired to be on all the time with the ignition)
New battery
Wiring around the radiator was damaged which was causing the frequent fuses blowing - repaired
Accessory socket connections were the wrong way round...adjusted

So all in all, quite a bit of work was needed in the end (not helped by the KTM shop..)

Took it out for it's first proper run yesterday (after checking the headbolt tension last week after a few short local runs), did about 200kms and no issues :)

However the non-original (no name) exhaust is bloody loud and is still popping on deceleration. Won't change it straight away but think will look into alternatives, any suggestions for a replacement can?

It was doing 160km/h at 7,000 rpm. But still think it could do with a bit more 'oomph' in acceleration although it's way better now. Is replacing the can essential or can this be done by removing the snorkel and changing the jets?

ps thanks for the great info, all of which was useful :)

pps after a couple of out of town rides and some dirt roads, fuel economy was around 19-20km/L which is up on the previous 13.5km/L when it wasn't running well

.

Nice work Mike! Beautiful bike! Worth the investment I'd think. bier

De-Cell popping is normal but really noticeable when running a loud pipe. Ditch that pipe! Changing jetting can alter popping but for the most part it will be there
no matter what.

Best look to 640 experts for suggestions on opening air box, changing needle and re-jetting. If done right, the BST40 carb has a lot of potential to get the most out of your bike ... and still get decent fuel economy. Lots of options. :thumbup1:

There must be other pipes you can run that breath well but aren't obnoxious.

Good luck, keep an eye on the head gasket, rockers and valve clearance.

Got a FCR 41 installed some weeks ago on my 2002 640 Adv, a much better bike!

Little update since I relocated to Penang a couple of months ago. I got a local mechanic recommended to me re-jet it without changing the exhaust and there was huge difference in the power delivery and also a reduction in the exhaust popping.

Just been for a 5 day jaunt to Thailand and it behaved very well on and off the highway. Still getting around 19km/L running the 16/42 sprockets. Couldn't tell you what jetting was used (I did ask..) but happy with results although I am curious on the FCR41 and different gearing options..I guess it's all a work in progress ;)