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 05-05-2013, 01:49 PM   #1
MrBob OP
Jambo!
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,391
KLX won't idle

My KLX 400 has the Keihin fcr39 carb. I bought the bike in southern CA, at a pretty low elevation. Most of my riding here in N.M. is 7,000 feet or above.
I haven't made any changes to the carb and until recently all seemed copacetic but thrashing through the mountains today the engine began to run rough and then refused to idle. It starts okay but I need to give it a little bit of throttle when starting. Normally, it's hands off of the throttle when starting with this carb. It accelerates as usual - strong.
Obviously, something changed in the idle or pilot circuit. I'm going to pull the tank and look for loose stuff because the bike has been ridden hard on rough trails lately, but what else am I missing.
If you wish to make suggestions, it would be more helpful if you know something about this particular carb, which is new to me.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad

MrBob screwed with this post 05-05-2013 at 02:46 PM
MrBob is offline   Reply With Quote
Old 05-05-2013, 02:38 PM   #2
Beezer
Beastly Adventurer
 
Joined: Oct 2004
Location: Anchorage, formerly Spenard (hub of the universe)
Oddometer: 5,376
could be just some krud in the idle jets. drain the carb & catch the residue for inspection. if you find none it could still be clogged

or mebby the float is stuck and/or the needle isn't quite seated (or has a flake missing). this would let extra fuel in that screws up the low end the most due to high fuel level. you can test by drain the bowl. when it quits draining, turn on the fuel and bypass (or activate) the vac operated petcock. if more fuel comes out its not right

or run it at as low a RPM as you can for a few minutes & then check the plug for soot.

also, I have seen where guys have bypassed the vac petcock all together and didn't block the nipple on the manifold (or the hose comes off) and that gives an air leak. it screws with low speed the most because the percentage of extra air diminishes as the throttle is opened (lean mix throughout the range)
Beezer is offline   Reply With Quote
Old 05-05-2013, 02:49 PM   #3
MrBob OP
Jambo!
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,391
I just pulled the plug and it's wet and sooty - too much fuel. I'm wondering if I can lower the needle a notch without pulling the carb.
I should pull the carb and inspect it thoroughly and get the jet numbers but this is prime riding season, before the summer heat, and I want to spend every minute I can riding. Besides, Santa Fe absolutely sucks for finding parts and nearly everything needs to be ordered.
I also re-cleaned the air cleaner.

Edit: Yes you can access the needle pulling the carb. It's quite an easy task.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad

MrBob screwed with this post 05-05-2013 at 05:33 PM
MrBob is offline   Reply With Quote
Old 05-05-2013, 04:53 PM   #4
Beezer
Beastly Adventurer
 
Joined: Oct 2004
Location: Anchorage, formerly Spenard (hub of the universe)
Oddometer: 5,376
needle affects mostly the mid range (unless you change the taper)

if it was working ok & suddenly crapped pout it's prolly not a jet thing. on the other hand, at 7000 feet you will be rich with sea level jetting. the idle circuit you can probably adjust with the pilot screw... the top 1/4 throttle is controlled by the main jet

if it was a sudden event, ran good then not... I'm gonna stick with needle/float problem

maybe call Fred....

http://www.angelfire.com/ut/moab/parts_frames.html


he might have parts & is very quick on shipping
Beezer is offline   Reply With Quote
Old 05-05-2013, 09:24 PM   #5
MrBob OP
Jambo!
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,391
Quote:
Originally Posted by Beezer View Post
needle affects mostly the mid range (unless you change the taper)

if it was working ok & suddenly crapped pout it's prolly not a jet thing. on the other hand, at 7000 feet you will be rich with sea level jetting. the idle circuit you can probably adjust with the pilot screw... the top 1/4 throttle is controlled by the main jet

if it was a sudden event, ran good then not... I'm gonna stick with needle/float problem

maybe call Fred....

http://www.angelfire.com/ut/moab/parts_frames.html


he might have parts & is very quick on shipping
I basically agree with you, I've just been hoping to buy time during our prime riding time. It's crazy to ask a carb to operate at a 6500 foot elevation increase without adjustments but riding conditions in the Santa Fe area are near perfect right now.
I cleaned the plug and air cleaner and it's running per normal at the moment.
I've been shopping for jet kits and James Dean and 6Sigma are looking good. J.D. has a good reputation and the 6Sigma kit did wonders for my KLR 250.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad
MrBob is offline   Reply With Quote
Old 05-12-2013, 08:17 AM   #6
MrBob OP
Jambo!
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,391
Coughed up a hundred bucks for James Dean jet kit and remote mixture screw. Report to follow.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad
MrBob is offline   Reply With Quote
Old 05-12-2013, 08:26 AM   #7
DirtDad
Green Chile Guru
 
DirtDad's Avatar
 
Joined: Apr 2006
Location: Albuquerque NM
Oddometer: 1,540
Good move. I coughed up some money for a JD Jet Kit for my KLR,
last year. What a huge improvement. I waited on my previous KLR's,
to do the jet kit, and all I can say is Why?
__________________
Current rides:
2014 YZ250F 05 KTM300EXC 11 KLR65007KTM450EXC
04 GasGas 280, finally, my perfect stable.
DirtDad is offline   Reply With Quote
Old 05-18-2013, 07:42 PM   #8
MrBob OP
Jambo!
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,391
James Dean jet and needle installed - and they really woke up the mid-range. There may be still more power there but I don't think I'll need it. I'll know for certain when I get up to 10,000 feet.
The installation process was not much fun in that cramped space and after the first effort the float bowl leaked so I got to do it again. During the process I found a sticker on the frame saying it was a product of the Suzuki Motor Company.
I also installed the Scott external mixture adjustment screw and I haven't made up my mind about that 30 dollar expenditure yet.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad
MrBob 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 07:18 AM.


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