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Old 12-16-2008, 08:56 AM   #211
potatoho
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Quote:
Originally Posted by Tappet
Hey Creeper,

Re: these usual mods we discussed above Would it be advisable for me to put on the racing airbox cover & snorkel but NOT do the BST mods? or is the airbox cover useless without the carb work?

My view on tinkering with the carb (myself) is akin to witchcraft, so ideally I'd just to do the airbox cover. Worth it or not?

Thanks
Mark
YMMV. It depends mostly on how well the slide spring is balanced for low rpm. Sometimes opening the side cover can screw up the pressures just enough to make the low rpm slide movement less agile. The simplest way to determine this is to hook up an AFR and watch the part throttle delivery with roll on. If you can balance it so that the mixture is consistent, the BST runs very well. With airbox mods, this may require an increase in pilot or even a slightly lighter slide spring. Also inspect the needle for indications of wear.
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Old 12-16-2008, 08:20 PM   #212
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I know this threads been around for a while and I would just like to thank the Creeper and all else for the great info on our bikes in this thread.As a 06 640 adv owner, this thread really comes in handy.Keep it going boyz Thanks again PBD
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Old 12-17-2008, 07:58 PM   #213
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Yeh I'll second that - thanks Creeper & the gang. I've now done all of the usual suspect mods in this thread & my bike is on fire
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Old 12-18-2008, 11:09 AM   #214
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Hi Doug and Tappet,

Your welcome. Glad we can help.

C
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Old 12-18-2008, 08:10 PM   #215
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Merry Christmas, you creep.

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Old 12-28-2008, 02:57 AM   #216
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OK planet-sized LC4 brain people,

I have all the 'usual suspect' mods & loaded's mixture screw, however I'm having trouble finding the right mixture setting.

With the bike warm, the entire range between 2 to 3.5 turns out I have a slight stutter off idle when grabbing a handful of throttle, which at times kills the engine.

By this detailed description, does it sound to you whether the mixture is too lean or too rich? This may help me narrowing down testing of each .25 turn out.

Or does this suggest something else is wrong BST-wise. Carb & jets are spotless BTW.

Thanks
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Old 12-28-2008, 05:52 AM   #217
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Quote:
Originally Posted by Tappet
OK planet-sized LC4 brain people,

With the bike warm, the entire range between 2 to 3.5 turns out I have a slight stutter off idle when grabbing a handful of throttle, which at times kills the engine.

By this detailed description, does it sound to you whether the mixture is too lean or too rich? This may help me narrowing down testing of each .25 turn out.

Or does this suggest something else is wrong BST-wise. Carb & jets are spotless BTW.

Thanks
I had the same frustrating issue on my 2004 640A.

IMHO. The most likely solution is ?................Drill your slide to 3mm

Check out this thread.

KTM 640 Adventure LC4 - Bogs off idle

Best of luck! Happy New year to all!


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Old 12-28-2008, 06:15 AM   #218
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One more other relevant link

Look at Post #7

KTM 640 Adventure hesitation or stalling just off idle
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Old 12-28-2008, 07:42 AM   #219
Tappet
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Quote:
Originally Posted by positionsize
I had the same frustrating issue on my 2004 640A.

IMHO. The most likely solution is ?................Drill your slide to 3mm

Check out this thread.

KTM 640 Adventure LC4 - Bogs off idle

Best of luck! Happy New year to all!


.
Thanks positionsize, that's a great thread. Surprised its not in the index. Like others I was hesitant to drill the slide but will give it a shot now.

Cheers
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Old 12-29-2008, 06:28 AM   #220
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Old 12-30-2008, 07:45 AM   #221
meat popsicle
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Quote:
Originally Posted by Tappet
Thanks positionsize, that's a great thread. Surprised its not in the index. Like others I was hesitant to drill the slide but will give it a shot now.

Cheers
Join the club... many useful threads likely escape my notice, especially now that I am workin' at a job that requires my F/T attention, my lil' one is almost 4yo, and - shite I hardly get to ride! Nominations in the index thread would be welcomed.

Oh, the slide drilling will allow the needle jet/jet needle combo (1/4 to 3/4 throttle as I recall) to respond more rapidly to pressure changes, improving throttle response to a point (bigger holes is better, but only to the size noted in creeper's tuning thread).

Off-idle should be the pilot circuit, although I am no sexpert and have heard that all the jets (main, needle, and idle jet) all interact to some degree.
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Old 12-30-2008, 08:40 AM   #222
NICO
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Quote:
Originally Posted by meat popsicle
Join the club...especially now that I am workin' at a job that requires my F/T attention, my lil' one is almost 4yo, and - shite I hardly get to ride!
Sounds like my world. Gotta figure out how to eliminate the work part of that equation.

Also gotta figure out how to get my 4yo to quit saying my bike is "pretty".
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Old 06-08-2009, 09:05 PM   #223
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Anybody seen this for sale online?

Quote:
Originally Posted by creeper
3. The air box is easy... either buy or make a copy of the KTM high flow air box side cover. Do not remove the snorkel on top the air box. Bear in mind that if you clean and re-oil the air filter, you bike will run richer than normal until the excess oil on the filter dissipates.
This mod improves air flow to the carburetor without upsetting the pressure balance required for it to work. Removing the snorkel is a recommendation made only when certain carb and exhaust conditions are met.

"584.06.003.200 LC4 (Small Airbox) Better airflow rate"


I've checked Munn and a search on KTM Talk with no luck. I did find it here http://www.ktm-parts.com/mm5/merchan...de=58406003200.

Are these things really $60? Anybody seen it somewhere else?

Edit: Bought one at KTMcycles.com and the purchase was hassle free and prompt.

I purchased one of the $225 Big Gun systems advertised here http://www.advrider.com/forums/showt...=465734&page=2 and am working on getting the bike set up for more air and fuel . Also looking at a db killer as mentioned in the Big Gun thread. Probably be a homemade job.

This setup thread has been great for a guy who's got more experience plugging in a powercommander than swapping jets. Thanks creeper
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Old 06-09-2009, 01:31 AM   #224
Norwegian Moose
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KTMcycles.com has the airbox cover for 29.99. No experience with them yet.
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Old 06-14-2009, 11:55 PM   #225
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Another satisfied customer. I did all the changes at once, which is poor technique for performing mods but I'm an impatient and busy guy. I just wanted it to run better and didn't care (as much) which change made the difference. There was some faith thrown in as well since these mods are now well tested. Below is a summary of my results.

Quote:
Originally Posted by creeper
'02 and earlier BST40 equipped bike info too, ...
Yup, that's what I have, a 2000 LC4E.

1. Main jet.
(2002 and earlier bikes have a 142.5 main jet stock... a good place to start there is a 150.0 to 152.5)
Started with a 150.0.

2. a. Changing the needle clip.
Put the clip on the fourth level.

2. b. Drilling the slide.
Did that.

A note about cutting springs.
Didn't do that.

2. c. Pilot fuel and air jets.
(some 2002 and earlier bikes, those that are not equipped with the "high flow" cylinder head do seem to benefit from a slightly richer pilot circuit)
Put in the bigger pilot fuel jet.

3. The air box is easy... either buy or make a copy of the KTM high flow air box side cover. Do not remove the snorkel on top the air box.
Bought the screened side cover & left the snorkel in place.

4. Modifying the stock muffler.
My stock muffler and pre-silencer were stolen. Bought a "tube" pre-silencer (part #58305175400) instead of the stock bigger pre-silencer and a "sparky" SXC main silencer (part #58305082100)

5. Fine Tuning
The idea here is to use the screw to optimize the transition from the pilot circuit to the needle circuit... not get a perfect idle mixture.
This has to be one of the best pieces of advice I've read in a while. Go back to page 1 and read this part again. While Creeper's words seem obvious, I don't think they appear anywhere else in print. All the advice you'll read from any source is to set the pilot circuit to acheive the best idle. When I did that I would get a delay when blipping the throttle from closed or starting from a stop. By turning the pilot screw in 1/2 turn I went from ideal idle mixture to ideal transition mixture. Thanks again Creeper!

Loadedagain has made a quantity of extended screws (like the ZipTy FCR ones) for the BST40.
Got one. Quality stuff and makes life easy.
Overall throttle response is greatly improved with an instant reaction to a twist of the wrist. My last bit of work was fiddling with the Loaded's pilot screw to get it right. By using Creeper's advice on how to set the pilot screw (focus on transition from idle and not on the best idle) my old LC4 is running fine indeed.

I had a bit of a time figuring out how to choose a main jet. Everybody seems to do it differently http://www.advrider.com/forums/showthread.php?t=469753 The advice here runs all over the place and folks tend to forget to say whether they are talking about an '02 and earlier or '03 and later when giving advice. Also, I tried a full range of main jets (150 - 157.5) and I just couldn't tell enough by seat of the pants testing.

I ended up using a different method that I think turned out well. Near my home is a straight stretch of highway with about 5% grade. After some test runs I found landmarks so the road, grade, and distance allowed me to start at 50 MPH in fourth gear and accelerate to about 80 MPH by the end. Each run took about 13 seconds and the stretch turned out to be about 1/4 mile. With my 16:45 gearing in fourth gear this starts at about 5,000 RPM and goes to about 7,500 RPM which should coincide with the range between max torque and max horsepower.

Just running it with the different main jets didn't really give a clear picture. The differences were too subtle. I can see why different people end up all over the place with a final choice. What did work was taking the average top speed for 3 runs with each main jet and using a GPS to check speed.

These buggars are a wonderful tool for this purpose. With the GPS you can start each run with +/- 0.5 MPH consistency. Then using the "max speed" screen you get a top speed for each run to 0.1 MPH. Just re-set max speed and take another run. As I said, the actual differences are too small to really detect by seat of the pants or with a speedometer.

The total average difference in top speed at the end of the section was just over 1 MPH between the worst (150) and best (155) main jet. My results with the different main jets were: 150=80.17 MPH, 152.5=80.25 MPH, 155=81.20 MPH, and 157.5=80.57 MPH. Not much difference. Just to check I repeated the test a second day with similar results and the 155 main jet came out on top again.

A dyno and air/fuel instrument would be ideal but I don't have access and I don't have a shop in the area I trust enough to do it right.

The tube pre-silencer and SXC muffler worked out OK. They're just a little louder than I like but I like quiet. They are not much louder than the SuperTrapp setup at idle and cruise but have a voice when the throttle is opened up. Even then they are not loud. I'll have to look elsewhere to save lives.

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