ADVrider

Go Back   ADVrider > Bikes > Thumpers
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-08-2004, 02:59 PM   #1
Barry OP
Just Beastly
 
Barry's Avatar
 
Joined: Oct 2002
Location: Fredericksburg, Va.
Oddometer: 7,146
OK - I searched, really... I did. But I STILL have a jetting question on 2001 640

I found a nice thread on jetting, and it made sense.

But, I still have a question....

I have a 2001 640 Adventure. I opened the airbox, have a IDS2 can on order, and my question is....

What jets sizes should I have on hand to properly tune/jet the thing? I believe the 2001 has the Mikuni.

Also, when popping in jets, other than sputtering (lean?) or maybe blowing black smoke (rich) (note - I've never jetted anything) how do I know I've got the optimal configuration beyond dyno and exhaust gas analyzing???

Thanks to all of you for your patience and indulgence. I'm so stoked about uncorking this beast.

Barry
__________________
Tail of the Dragon at Deal's Gap... Avoid it now, do a trackday.

Do not do business with Myrtle West Cycle... Not a reputable vendor by a long shot.
Barry is offline   Reply With Quote
Old 11-08-2004, 04:03 PM   #2
laramie LC4
crash test dummy!
 
laramie LC4's Avatar
 
Joined: Sep 2004
Location: Tucson, Az
Oddometer: 2,345
#1- yes, your bike has the Mikuni BST-40 CV Carb, unless of course it's been changed from stock

#2- you will probably be running a 165-175 main jet, they run in units of 2.5 (ie. 160, 162.5, 165, 167.5, ... ) , and make sure you get the large round headed jets, not the small headed ones.

#3- you may want to also jump to the larger secondary jet of 47.5, the stock is 45. these are the only 2 options.

#4- here is a great site for explaining how to jet, it is for a Kawasucki but the principles are all the same http://justkdx.dirtrider.net/carbtuning.html

#5- since messing with the stock jetting, replacing the stock silencer (IDS2 with 12 disks), using racing airbox cover instead of stock, my bike always pops on decel. i've asked about this several times and read manya post about it and have come to the conclusion that it's due to the CV carb and not poor jetting.

good luck and have fun! your bike is going to feel like and sound like a monster when your done!!

laters,

laramie
__________________
DON'T TRUST CUT 7! HE IS A CROOK! ASK ME HOW I KNOW.

'12 LC8 990R, '02 LC4 640, '05 WR 450f (part-out), '98 XR400R, '76 KE100, '05 525 (Step-Child)
laramie LC4 is offline   Reply With Quote
Old 11-08-2004, 05:52 PM   #3
ChrisC
Molon Labe
 
ChrisC's Avatar
 
Joined: Feb 2003
Location: Prescott, Arizona USA Earth
Oddometer: 6,313
Jetting

Barry,

Head over to ktmtalk.com and search the dual-sport area for "jetting". You'll have hours of fun.

Here's one thread started by Laramie hisself....

LC4 jetting

p.s. I'm guessing the right main jet for your bike at sea level will be about 157.5 (everybody here tends to go a little fat... )
__________________
Chris
'03 KTM Adventure 640
'43 BSA M20WD
ChrisC is offline   Reply With Quote
Old 11-09-2004, 02:41 AM   #4
Barry OP
Just Beastly
 
Barry's Avatar
 
Joined: Oct 2002
Location: Fredericksburg, Va.
Oddometer: 7,146
thanks guys...

I figured you guys had already decided on the optimal configuration.

More ????s:

1) What does the secondary jet do???

2) If I remove the floatbowl, I'll just see the jets there and be able to unscrew them?

Thanks again,
Barry
__________________
Tail of the Dragon at Deal's Gap... Avoid it now, do a trackday.

Do not do business with Myrtle West Cycle... Not a reputable vendor by a long shot.
Barry is offline   Reply With Quote
Old 11-09-2004, 06:23 AM   #5
meat popsicle
Ignostic
 
meat popsicle's Avatar
 
Joined: Feb 2004
Location: Circumlocution Office of Little Dorrit
Oddometer: 14,160
Quote:
Originally Posted by Barry
I figured you guys had already decided on the optimal configuration.

More ????s:

1) What does the secondary jet do???

2) If I remove the floatbowl, I'll just see the jets there and be able to unscrew them?

Thanks again,
Barry
matey peeps gotcha covered:

http://www.advrider.com/forums/showt...31#post1015631

http://www.speedskater.info/modules....ownload&cid=11

schweet!
__________________
Kronreif Trunkenpolz Mattighofen LC4 640

Its not so much staying alive; its staying human that counts.
meat popsicle is offline   Reply With Quote
Old 11-09-2004, 07:03 AM   #6
Arch
Incurable Gearhead
 
Arch's Avatar
 
Joined: Dec 2001
Location: Katy, TX
Oddometer: 11,705
Quote:
Originally Posted by Barry
I figured you guys had already decided on the optimal configuration.
The "optimal configuration" is bike specific, but we can get you close. I've posted the following before, but the search engine awaits tweaking, so I hope the inmates will pardon the repetition.

First of all, just for reference, your stock main jet should be a 142.5. I'm near sea level and run a 157.5 (open airbox, SXC muffler) most of the time. For our mountain/desert adventures, I drop in a 155 or so, depending on the season. A selection of sizes say from 150~ish to 165 will give ya plenty to work with to dial yours in. Stock up - they're cheap.

Getting at the main is easy on the '01 because there's plenty of clearance beneath the carb, so just remove the big nut on the bottom of the float bowl and there's your main jet right there. There'll be a little collar that comes off with it, so be careful not to lose that. I've done it a bunch of times with a stubby screwdriver, but using Motion Pro's main jet wrench makes it even easier. "8mm Round Part Number: 08-0024" as shown on http://www.motionpro.com/Docs/convtools_2.html. After a few times, you should be able to swap a main jet out in a couple of minutes, start to finish.

The air jet is located in the carb's bellmouth, recessed into one of a couple of holes, with its screw slot facing the airbox. You'll wanna put a 1.1 in there. Here's an easy carb access tip: Remove the exhaust mount bolt just above the chain roller, along with the muffler's springs. Then loosen the clamp that secures the airbox to the carb and remove the subframe's upper mount bolts. Slowly pivot the subframe down towards the tire while watching to see which (if any) of the electrical connectors need to be unplugged to avoid pulling. The airbox will pop off the carb and you'll be able to remove it (the carb) with ease. Be VERY careful with the tiny air jet's threads and screwdriver slot.

Then just dial in the mixture screw like on most any other bike. Turns are counted outwards from lightly seated. Here's a handy guide...
http://204.71.0.3/motoprof/moto/mcycle/carb101/carb101.html

Some relevant threads...
http://www.advrider.com/forums/showthread.php?t=43593
http://www.advrider.com/forums/showthread.php?t=36558

I believe in supporting your local shop, but here's a nice online resource for part numbers and schematics...
http://www.ktminfo.com/partscat/catalog.asp
Specific to your carb...
http://www.ktminfo.com/partscat/Parts.asp?Page=01584312&Cat=320827&CatID=127

Also, since the bike is new to you, here's a blurb about friendly gearing in case you ever feel the need: To keep your chain length the same and be able to easily swap street/dirt gearing as needed, go up one tooth in the front, and down two in the rear.

17t countershaft sprocket, ktm part # 58033029017.
40t rear sprocket, ktm part # 58310151040.

You'll need to take a belt sander to the removable case protector to fit the larger countershaft sprocket, or order up the one that they use on the duke (ktm part # 58430047000). Either way it's a no-brainer.

Soooooo, long story short, here's my typical setup and few part numbers...
17t countershaft sprocket, KTM part #58033029017.
40t rear sprocket. KTM part #58310151040.
KTM SXC muffler is part #58305081300.
Open airbox cover is part # 58406003200.
Main jet 157.5-ish, air jet 1.1.
Euro tool carrier thingy is KTM part #58012058000.

YMMV, and then some.
__________________
Arch
Arch is offline   Reply With Quote
Old 11-09-2004, 07:16 AM   #7
Barry OP
Just Beastly
 
Barry's Avatar
 
Joined: Oct 2002
Location: Fredericksburg, Va.
Oddometer: 7,146
THANKS ~!


but, what does the 1.1 jet thingy do? is that idle?
__________________
Tail of the Dragon at Deal's Gap... Avoid it now, do a trackday.

Do not do business with Myrtle West Cycle... Not a reputable vendor by a long shot.
Barry is offline   Reply With Quote
Old 11-09-2004, 09:06 AM   #8
meat popsicle
Ignostic
 
meat popsicle's Avatar
 
Joined: Feb 2004
Location: Circumlocution Office of Little Dorrit
Oddometer: 14,160
Quote:
Originally Posted by Arch
I've posted the following before, but the search engine awaits tweaking, so I hope the inmates will pardon the repetition.
That's not repetition that's helpful, especially with the search engine down.
__________________
Kronreif Trunkenpolz Mattighofen LC4 640

Its not so much staying alive; its staying human that counts.
meat popsicle is offline   Reply With Quote
Old 11-09-2004, 10:13 AM   #9
dirtrider
Dusty Adventurer
 
dirtrider's Avatar
 
Joined: Nov 2003
Location: Kalispell, Montana
Oddometer: 3,314
Quote:
Originally Posted by Arch
The "optimal configuration" is bike specific, but we can get you close. I've posted the following before, but the search engine awaits tweaking, so I hope the inmates will pardon the repetition.

First of all, just for reference, your stock main jet should be a 142.5. I'm near sea level and run a 157.5 (open airbox, SXC muffler) most of the time. For our mountain/desert adventures, I drop in a 155 or so, depending on the season. A selection of sizes say from 150~ish to 165 will give ya plenty to work with to dial yours in. Stock up - they're cheap.

Getting at the main is easy on the '01 because there's plenty of clearance beneath the carb, so just remove the big nut on the bottom of the float bowl and there's your main jet right there. There'll be a little collar that comes off with it, so be careful not to lose that. I've done it a bunch of times with a stubby screwdriver, but using Motion Pro's main jet wrench makes it even easier. "8mm Round Part Number: 08-0024" as shown on http://www.motionpro.com/Docs/convtools_2.html. After a few times, you should be able to swap a main jet out in a couple of minutes, start to finish.

The air jet is located in the carb's bellmouth, recessed into one of a couple of holes, with its screw slot facing the airbox. You'll wanna put a 1.1 in there. Here's an easy carb access tip: Remove the exhaust mount bolt just above the chain roller, along with the muffler's springs. Then loosen the clamp that secures the airbox to the carb and remove the subframe's upper mount bolts. Slowly pivot the subframe down towards the tire while watching to see which (if any) of the electrical connectors need to be unplugged to avoid pulling. The airbox will pop off the carb and you'll be able to remove it (the carb) with ease. Be VERY careful with the tiny air jet's threads and screwdriver slot.

Then just dial in the mixture screw like on most any other bike. Turns are counted outwards from lightly seated. Here's a handy guide...
http://204.71.0.3/motoprof/moto/mcycle/carb101/carb101.html

Some relevant threads...
http://www.advrider.com/forums/showthread.php?t=43593
http://www.advrider.com/forums/showthread.php?t=36558

I believe in supporting your local shop, but here's a nice online resource for part numbers and schematics...
http://www.ktminfo.com/partscat/catalog.asp
Specific to your carb...
http://www.ktminfo.com/partscat/Parts.asp?Page=01584312&Cat=320827&CatID=127

Also, since the bike is new to you, here's a blurb about friendly gearing in case you ever feel the need: To keep your chain length the same and be able to easily swap street/dirt gearing as needed, go up one tooth in the front, and down two in the rear.

17t countershaft sprocket, ktm part # 58033029017.
40t rear sprocket, ktm part # 58310151040.

You'll need to take a belt sander to the removable case protector to fit the larger countershaft sprocket, or order up the one that they use on the duke (ktm part # 58430047000). Either way it's a no-brainer.

Soooooo, long story short, here's my typical setup and few part numbers...
17t countershaft sprocket, KTM part #58033029017.
40t rear sprocket. KTM part #58310151040.
KTM SXC muffler is part #58305081300.
Open airbox cover is part # 58406003200.
Main jet 157.5-ish, air jet 1.1.
Euro tool carrier thingy is KTM part #58012058000.

YMMV, and then some.
Awesome post Arch! Very informative.

I did the carb mods on my bike when it had over 8K on it and wondered why the hell I hadn't done it sooner. The bike runs much smoother and has more power. A couple of other things I have done to my carb are to drill the slide holes to 3mm and cut two coils from the diaphram spring. Both of these mods increase throttle response as the slide moves quicker and easier. On my engine, I also installed a thinner base gasket to increase compression which made a noticeable difference.
__________________
2013 Husky TE511
2014 KTM 350 XC-F
2006 KTM Adv 950
2001 KTM 640 LC4 Sold
I only like two kinds of women, foreign and domestic
dirtrider is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 06:57 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014