Elevation and effect on carb/exhaust mods - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

 12Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 33 Old 03-04-2017, 11:46 AM Thread Starter
1st Gear
 
Join Date: Feb 2017
Posts: 45
Elevation and effect on carb/exhaust mods

I'm a new '16 KLR owner and appreciate having so much info available on the forum. The KLR loyal following was the final factor in my decision.

I live at 7,000' in CO and will be spending a lot of trail time at higher elevations, 11k - 12k. I'm not an aggressive rider and am closer to 50/50 pavement/trail.

The bike is stock with no mileage. However, I have a lot of basic mods sitting here and ready to go, including SW crash bars, skid plate, Moab shock/DDC package, KLR dash, ZG windshield and Lexx MXe exhaust.

So regarding performance mods, I would like to know more about the theoretical influence of elevation in common mods, including the .22 mod and need for air flow mods for the lexx exhaust. In theory, would the combination of shimming the needle and thinner air create an overly rich mixture? I feel doing the mod and then adjusting mixture is the best option but would like experienced opinions.

Also, what's the take on any beneficial mods combined with the new exhaust? Elevation would only influence combustion and not be a factor in the exhaust, correct?

I appreciate all of the help and experience!!

Thanks!!
Jhawker23 is offline  
Sponsored Links
Advertisement
 
post #2 of 33 Old 03-04-2017, 12:55 PM
5th Gear
 
Join Date: Jan 2011
Posts: 4,333
The trick exhaust (gracious, I hope you don't get any trails closed from the increased noise!) increases gas flow through the engine (more accurately, reduces flow restriction). The effect is a modest fuel-leaning; perhaps to the good at your altitude.

22-cent mod? You might not need it; the effect is fuel-enriching the mixture in mid-range throttle operation.

Fuel screw adjustment? Affects mixture from idle to maybe 1/8-1/4 throttle; might need to tighten it somewhat.

Main jet? Maybe go a little smaller than stock. An exhaust gas analyzer would go a long way in answering your questions; maybe a dyno run with air/fuel ratio plot would tell a lot.

Realize: Even with OPTIMUM air/fuel ratio, some power loss remains inevitable at altitude.
Jhawker23 likes this.
Damocles is offline  
post #3 of 33 Old 03-04-2017, 01:34 PM
4th Gear
 
GoMotor's Avatar
 
Join Date: May 2014
Location: Texas
Posts: 1,250
The diaphragm mechanism in the constant velocity carburetor on the KLR helps it adjust to the air density at different elevations and keep the proper fuel/air ratios. I have ridden my KLRs with the 0.22 mod from below sea level in Death Valley up to 13,000 feet on California Pass in Colorado with no no adjustments and no problems.

Obviously if there is 30% less air/oxygen per cubic foot, the engine will produce 30% less power, but that applies to all engines.
shinyribs and Jhawker23 like this.
GoMotor is offline  
 
post #4 of 33 Old 03-04-2017, 06:31 PM Thread Starter
1st Gear
 
Join Date: Feb 2017
Posts: 45
Thanks for the help! If I'm watching for a too rich mixture, what symptoms should I expect? Other signals aside from watching plugs?
Jhawker23 is offline  
post #5 of 33 Old 03-04-2017, 06:38 PM
4th Gear
 
GoMotor's Avatar
 
Join Date: May 2014
Location: Texas
Posts: 1,250
Black smoke from the exhaust indicates a rich condition for a gasoline engine. The richer the more smokey.
Jhawker23 likes this.
GoMotor is offline  
post #6 of 33 Old 03-04-2017, 06:49 PM Thread Starter
1st Gear
 
Join Date: Feb 2017
Posts: 45
Quote:
Originally Posted by GoMotor View Post
Black smoke from the exhaust indicates a rich condition for a gasoline engine. The richer the more smokey.
Thanks GoMotor... makes sense...
Jhawker23 is offline  
post #7 of 33 Old 03-04-2017, 09:52 PM
5th Gear
 
Join Date: Oct 2011
Location: Lac La Biche Alberta Canada
Posts: 3,205
The KLR comes from the factory jetted very lean to meet emission regs. I'll bet yours will be just about perfect to run as is at 7 to 12000ft! Much better than than sea level bikes!
JJ

It's not a Tractor....It's a LOCOMOTIVE!! Chugga Chugga
Woooo WOOOOO!!!!!
justjeff is offline  
post #8 of 33 Old 03-05-2017, 08:42 AM Thread Starter
1st Gear
 
Join Date: Feb 2017
Posts: 45
Quote:
Originally Posted by Damocles View Post
The trick exhaust (gracious, I hope you don't get any trails closed from the increased noise!) increases gas flow through the engine (more accurately, reduces flow restriction). The effect is a modest fuel-leaning; perhaps to the good at your altitude.

22-cent mod? You might not need it; the effect is fuel-enriching the mixture in mid-range throttle operation.

Fuel screw adjustment? Affects mixture from idle to maybe 1/8-1/4 throttle; might need to tighten it somewhat.

Main jet? Maybe go a little smaller than stock. An exhaust gas analyzer would go a long way in answering your questions; maybe a dyno run with air/fuel ratio plot would tell a lot.

Realize: Even with OPTIMUM air/fuel ratio, some power loss remains inevitable at altitude.
I've already drilled out the slide to 7/64. If I don't use the spacer, are there any concerns or just potential to be a little leaner?
Jhawker23 is offline  
post #9 of 33 Old 03-05-2017, 11:18 AM
5th Gear
 
Join Date: Oct 2011
Location: Lac La Biche Alberta Canada
Posts: 3,205
Nope! All the slide drilling does is enable the slide to move a little quicker as you open and close the throttle for better throttle response.. Drilling the slide has no effect on jetting.
JJ
Jhawker23 likes this.

It's not a Tractor....It's a LOCOMOTIVE!! Chugga Chugga
Woooo WOOOOO!!!!!
justjeff is offline  
post #10 of 33 Old 03-05-2017, 12:49 PM Thread Starter
1st Gear
 
Join Date: Feb 2017
Posts: 45
Quote:
Originally Posted by justjeff View Post
Nope! All the slide drilling does is enable the slide to move a little quicker as you open and close the throttle for better throttle response.. Drilling the slide has no effect on jetting.
JJ
Thanks JJ! What about downsizing the main jet? I have a lexx mxe going on shortly.

I'm trying to sort out what mods are beneficial vs. detrimental because of elevation.

Last edited by Jhawker23; 03-05-2017 at 01:00 PM.
Jhawker23 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki KLR 650 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
A question concerning carb and exhaust mod. Two Dogz 2008+ KLR650 Wrenching & Mod Questions 14 05-14-2014 11:01 PM
Carb jetting with DG exhaust wvstumpjumper 2008+ KLR650 Wrenching & Mod Questions 1 03-08-2014 10:50 AM
Exhaust Mods biglar 2008+ KLR650 Wrenching & Mod Questions 4 11-25-2012 09:26 PM
effect of 685 upgrade on gas mileage? Dwell 1987 to 2007 Wrenching & Mods 7 09-02-2009 10:12 AM
Rejetted for Elevation 4wheeldog KLR & Other Motorcycle Related Discussion 1 06-20-2007 11:36 PM

Posting Rules  
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome