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 01-06-2012, 12:15 PM   #2056
Mo-Tarded
Gnarly Adventurer
 
Mo-Tarded's Avatar
 
Joined: Jun 2008
Location: Show Low, AZ, USA
Oddometer: 162
Lord: I dunno... 155 may be marginally small. Not a direct comparison, but my FCR jets on my (450cc) dirt bike are about 175. If you go bigger on the main, you may need to drop the needle.

It should be regulating from about 1/4 to 3/4 on the pilot jet. With your mods and symptoms, it may be slightly lean (my guess).

BTW... My BST does almost the same thing. However if I roll through the dead zone it feels mostly normal.

Whatever you do let's not go test it under load on ice.

Here is the BST Bible guideline thread: http://www.advrider.com/forums/showthread.php?t=347184

Others here know more than I do. Do one small change at a time.
__________________
"Our lives can be spent carrying out actions that we hope will lead us to a greater sense of purpose, accomplishment and meaning, but all these are secondary to the need to feel alive." - AntiHero ADV Rider
Mo-Tarded is offline   Reply With Quote
Old 01-06-2012, 12:49 PM   #2057
Lortdadu
Joe Cool
 
Lortdadu's Avatar
 
Joined: Aug 2010
Location: Finland
Oddometer: 207
Quote:
Originally Posted by Mo-Tarded View Post
Lord: I dunno... 155 may be marginally small. Not a direct comparison, but my FCR jets on my (450cc) dirt bike are about 175. If you go bigger on the main, you may need to drop the needle.

It should be regulating from about 1/4 to 3/4 on the pilot jet. With your mods and symptoms, it may be slightly lean (my guess).

BTW... My BST does almost the same thing. However if I roll through the dead zone it feels mostly normal.

Whatever you do let's not go test it under load on ice.

Here is the BST Bible guideline thread: http://www.advrider.com/forums/showthread.php?t=347184

Others here know more than I do. Do one small change at a time.
Thanks for the tips. I've read the BST Bible a few times already, it seems as if the BST is filled with mysteries and magic!

Today strangely, I fired it up, coolant got to about 40C, then it shut off, didn't want to fire up without choke, so I put on the choke and it ran for a few seconds and died again. Going to make a few trials during the weekend, see if the plug gets wet etc..
Lortdadu is offline   Reply With Quote
Old 01-06-2012, 01:24 PM   #2058
gunnerbuck
Island Hopper
 
gunnerbuck's Avatar
 
Joined: Nov 2005
Location: N.V.I, B.C.
Oddometer: 3,716
Yes, it is likely that a 155 will cause your 400 to be on the rich side...

I have a high flo 640 and run a 155 with an opened pipe + sidecover on and switch to 157.5 with open sidecover...

With your 400 I would think 147.5 or 150 would be ballpark, what did it come with stock?
gunnerbuck is offline   Reply With Quote
Old 01-06-2012, 02:30 PM   #2059
Lortdadu
Joe Cool
 
Lortdadu's Avatar
 
Joined: Aug 2010
Location: Finland
Oddometer: 207
Quote:
Originally Posted by gunnerbuck View Post
Yes, it is likely that a 155 will cause your 400 to be on the rich side...

I have a high flo 640 and run a 155 with an opened pipe + sidecover on and switch to 157.5 with open sidecover...

With your 400 I would think 147.5 or 150 would be ballpark, what did it come with stock?
Those were exactly the two jets I was thinking of buying. My bike came with a 142.5 stock, and the package I bought with an open side cover and a jetting and carb tuning guide was 155 and a 160 (though the jets were meant for a 640 ). So I put in the 155 to test how it runs.

I'm hoping to push out about 45HP with these performance upgrades.
Lortdadu is offline   Reply With Quote
Old 01-07-2012, 08:58 AM   #2060
Tonicu
Gnarly Adventurer
 
Joined: Dec 2011
Location: Spain
Oddometer: 161
Coolant temperature issue 640 LC4 Enduro '03

500 kms. done after my rocker bearings and camshaft change, the engine seems to be back in good shape. However, I've noticed that when ridden quite hard at steepy&narrow slow enduro tracks the stripes on the panel go quickly up from the 2 or 3 to five, then the fan kicks in. Everything normal so far, but when at those five stripes, it expulses some coolant through the cap hose that goes to the chasis. I thought it'd be a mere question of too much coolant added after fixing the cam&timing gear, but it apparently isn't the case. Maybe some air got in?
What temperature - how many stripes - do you normally see in your panel both running smoothly and as if you'd had stolen it?
Tonicu is offline   Reply With Quote
Old 01-07-2012, 10:30 AM   #2061
gunnerbuck
Island Hopper
 
gunnerbuck's Avatar
 
Joined: Nov 2005
Location: N.V.I, B.C.
Oddometer: 3,716
Quote:
Originally Posted by Tonicu View Post
500 kms. done after my rocker bearings and camshaft change, the engine seems to be back in good shape. However, I've noticed that when ridden quite hard at steepy&narrow slow enduro tracks the stripes on the panel go quickly up from the 2 or 3 to five, then the fan kicks in. Everything normal so far, but when at those five stripes, it expulses some coolant through the cap hose that goes to the chasis. I thought it'd be a mere question of too much coolant added after fixing the cam&timing gear, but it apparently isn't the case. Maybe some air got in?
What temperature - how many stripes - do you normally see in your panel both running smoothly and as if you'd had stolen it?
My 640 runs constantly at 4 bars and once in a while will climb to 5 bars on slow tight trails or slow steep climbs... It never spews coolant unless I fill the rad to the top... The rad coolant level should sit about 1cm above the tubes and well below the top of the filler neck...
gunnerbuck is offline   Reply With Quote
Old 01-07-2012, 12:46 PM   #2062
Tonicu
Gnarly Adventurer
 
Joined: Dec 2011
Location: Spain
Oddometer: 161
That should be it, then. I filled it up to the filler neck.
Cheers!
Now looking for some spare time for the sprag clutch spring change. You never get bored with a LC4!
Tonicu is offline   Reply With Quote
Old 01-07-2012, 01:06 PM   #2063
MNCherryinCA
KTM Noob
 
Joined: Mar 2011
Location: Santa Clarita, CA
Oddometer: 577
Quote:
Originally Posted by Tonicu View Post
That should be it, then. I filled it up to the filler neck.
Cheers!
Now looking for some spare time for the sprag clutch spring change. You never get bored with a LC4!
I think this must be the same problem on my 625SXC. I just got it back from the shop and its just barely above the tubes, well short of the neck. Hopefully no more spitting!
MNCherryinCA is offline   Reply With Quote
Old 01-07-2012, 10:43 PM   #2064
caribooster
Not enough time...
 
Joined: Oct 2006
Location: Langley & Cariboo, BC
Oddometer: 42
Quote:
Originally Posted by gunnerbuck View Post
My 640 runs constantly at 4 bars and once in a while will climb to 5 bars on slow tight trails or slow steep climbs... It never spews coolant unless I fill the rad to the top... The rad coolant level should sit about 1cm above the tubes and well below the top of the filler neck...
My 640E runs the same temperature, I have some of the AmsOil special coolant treatment that I will be running this year to see if it makes any difference. I have occassionally run the temperature guage into the red but by that time I by own blood pressure is ready to blow a head gasket.
caribooster is offline   Reply With Quote
Old 01-07-2012, 10:54 PM   #2065
slackmeyer
Don't mean sheeit. .
 
slackmeyer's Avatar
 
Joined: Jul 2007
Location: Berzerkeley, CA
Oddometer: 2,911
Quote:
Originally Posted by Tonicu View Post
That should be it, then. I filled it up to the filler neck.
Cheers!
Now looking for some spare time for the sprag clutch spring change. You never get bored with a LC4!
I just fixed my sprague clutch! Just tighten the spring (unthread the male end, cut 20-30mm off female end, reinsert), no reason to replace it unless it's all fubared. I was getting embarrassed about all the noise my bike was making trying to start it. . .

On a related note, my bike has trouble starting when cold on the electric start- the starter seems to work great, the battery is new, but the bike turns over and doesn't quite start. I follow the standard procedure with the kicker, and it starts up within a few kicks- and then the starter works with the bike warm. Any advice? I'm thinking I left the bike to sit a bit too long this fall, and I'm due for another carb cleaning.
__________________
Zak

ktm
old bmw
others
slackmeyer is offline   Reply With Quote
Old 01-08-2012, 06:15 AM   #2066
KTM AL
Gnarly Adventurer
 
Joined: Jun 2007
Oddometer: 104
are there any threads on cam shaft replacement

Zac, not sure if your having the same problem I am, Mine won't turn past tdc on compression(yes I use the manual lever and it spins, but stops when released), after a lot of testing and reading many threads, I'm pretty sure the autodecomp is worn down and not working, can anyone show me a thread about cam replacement on the LC4, thanks.

Al
KTM AL is offline   Reply With Quote
Old 01-08-2012, 06:19 AM   #2067
Lortdadu
Joe Cool
 
Lortdadu's Avatar
 
Joined: Aug 2010
Location: Finland
Oddometer: 207
Quote:
Originally Posted by KTM AL View Post
Zac, not sure if your having the same problem I am, Mine won't turn past tdc on compression(yes I use the manual lever and it spins, but stops when released), after a lot of testing and reading many threads, I'm pretty sure the autodecomp is worn down and not working, can anyone show me a thread about cam replacement on the LC4, thanks.

Al
The cam may not necessarily have been worn out. The spring under the autodecomp mechanism may have worn out, the repair manual says it should not be less than 7mm in length. Mine was worn out, got it fixed by changing the spring under the autodecomp mechanism.

Also, this thread might tell you a bit about the cam as well. http://www.advrider.com/forums/showthread.php?t=670733
Lortdadu is offline   Reply With Quote
Old 01-08-2012, 08:15 AM   #2068
meat popsicle OP
Ignostic
 
meat popsicle's Avatar
 
Joined: Feb 2004
Location: Circumlocution Office of Little Dorrit
Oddometer: 14,132
Quote:
Originally Posted by KTM AL View Post
Zac, not sure if your having the same problem I am, Mine won't turn past tdc on compression(yes I use the manual lever and it spins, but stops when released), after a lot of testing and reading many threads, I'm pretty sure the autodecomp is worn down and not working, can anyone show me a thread about cam replacement on the LC4, thanks.

Al
Hey Al,

with all the chatter in here its really hard to keep up with the actual Index Thread questions, so sorry if I've missed any. So if you search something like Google for:

site:www.advrider.com lc4 camshaft

You'll get a bunch of hits like:
http://www.advrider.com/forums/showthread.php?t=713833
http://www.advrider.com/forums/showthread.php?t=596666
http://www.advrider.com/forums/showthread.php?t=286283 (indexed already)
http://www.advrider.com/forums/showthread.php?t=412931
http://www.advrider.com/forums/showthread.php?t=114049
http://www.advrider.com/forums/showthread.php?t=399867
http://www.advrider.com/forums/showthread.php?t=564466
(just the first page of search results)

you're best source of advice on engine work is gunnerbuck, although tseta and a host of others seem to know their shit, and Laramie's LC4 teardown thread in the index should help too.
__________________
Kronreif Trunkenpolz Mattighofen LC4 640

Its not so much staying alive; its staying human that counts.
meat popsicle is offline   Reply With Quote
Old 01-09-2012, 03:31 AM   #2069
Alik
viertaKTMotor *****
 
Joined: Nov 2010
Location: Poznan, Poland
Oddometer: 199
Quote:
Originally Posted by Lortdadu View Post
Mkay, so I successfully did the main-shaft bearing change, installed my new parts (new exhaust, KTM SXC muffler, airbox side cover mod), and it fired up very well. Mines a LC4 400 with a Mikuni BST-40.

Now, here's what my set up is currently (Finland).

Main Jet: 155
Idle Jet: 45
Air Screw: 3 turns out
Needle clip: 4th position

When I throttle and reach about 1/4th of the throttle, it starts to bog. If I slowly give it more gas, it will get over the bogging and get better, and at high rpm's it responds well. Oh, and when I let go of the throttle between 1/4-5/8th? throttle, the exhaust pops quite nicely... I'm having a hard time believing that the mixture would be too lean for a 400cc LC4.. I'm going to grab different main jets tomorrow, I got a 155 & 160 from Schneider Cycles when I ordered the exhaust and another airbox cover.

The annoying part is I can't get my bike jetted properly for the summer because it's quite slippery to ride right now...

Any tips on adjustment?

EDIT: Bogging can be caused both by a lean and a rich mixture, am I right? And popping can be caused by one as well? Any recommendations on main jet sizes, I'm thinking that the 155 is way big.
Lort,

standard settings according to the manual:

MJ 147,5
Needle jet 689 X-6
Idling jet 45
Jet needle 6G5
Needle position 3rd from top + 1 mm
Mixture control screw open 2.25

Start from the standard setup and work it up one size a the time.
I would start with a 150 MJ and go no more than 152,5 MJ.
Also the standard needle postition for a 400 seems to be different than normal 640 setup which is on 3rd clip. There seems to be an additional 1mm washer involeved.
Turn down the mixture control to stock setup. And start to reasses the transition effect by turning it about increments at the time.

I think You should better post in the BST-40 Bible thread. you will find some more geeks lurking there ;)
Alik is offline   Reply With Quote
Old 01-09-2012, 07:24 AM   #2070
Lortdadu
Joe Cool
 
Lortdadu's Avatar
 
Joined: Aug 2010
Location: Finland
Oddometer: 207
Quote:
Originally Posted by Alik View Post
Lort,

standard settings according to the manual:

MJ 147,5
Needle jet 689 X-6
Idling jet 45
Jet needle 6G5
Needle position 3rd from top + 1 mm
Mixture control screw open 2.25

Start from the standard setup and work it up one size a the time.
I would start with a 150 MJ and go no more than 152,5 MJ.
Also the standard needle postition for a 400 seems to be different than normal 640 setup which is on 3rd clip. There seems to be an additional 1mm washer involeved.
Turn down the mixture control to stock setup. And start to reasses the transition effect by turning it about increments at the time.

I think You should better post in the BST-40 Bible thread. you will find some more geeks lurking there ;)
Alright, thanks. I'll try those, and post more in the BST-40 Bible thread if I need any more help! :)
Lortdadu 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 05:42 AM.


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