Jet kit 40mpg - 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.

 
LinkBack Thread Tools Display Modes
post #1 of 7 Old 03-16-2011, 11:39 PM Thread Starter
new
1st Gear
 
Join Date: Jul 2009
Posts: 30
Jet kit 40mpg

I installed a dynojet stage 2 kit and I'm getting 40MPG. I dont think it worth the lost of mpg, there is several jets that come with the kit. Does anyone know which jet work better for MPG and still have some power gains.I'm running stock gears and a drilled out muffler, snorkel removed. I put the bigger jet for stage 2 there a smaller jet for stage 2 and there is still stage 1 jets also.Does anyone have any input on this dynojet kit. Thanks
new is offline  
Sponsored Links
Advertisement
 
post #2 of 7 Old 03-16-2011, 11:55 PM
Pretty in Pink, dunno why
 
Tom Schmitz's Avatar
 
Join Date: Feb 2009
Location: Redondo Beach
Posts: 7,611
Garage
There are two ways that a jet kit can reduce your mpg.

First, it works real good and you use more throttle to get more thrills.

Second, it ain't working right and it's too rich.

I'm betting you're too rich. Reduce jet size and check again.

See, the only reason to increase jet size is because you've made some intake/exhaust mods and are running lean. Increasing the jet size brings you back to a proper mixture. Going overly large on a jet, such that it runs rich, does nothing but waste gas. It can't make more power without more air, which means more aggressive mods. I have no idea what the actual DJ jet sizes are that you're referring to. Do you have a cross reference to Keihin jet sizes? The most extreme mods that can be made to the KLR - intake, head, exhaust, are hard pressed to need more than a 147.5 jet with a KLX needle.

If you are at the proper mixture, the bike will not use more gas for a given situation. If you were getting 45mpg before the mods you should get 45mpg after the mods, as long as you don't change your driving style. The extra power that the mods made is potentially there, but doesn't come on (and use more gas) unless you twist the throttle.

T

Tom [email protected]

The kid poured him another straight rye and I think he doctored it with water down behind the bar because when he came up with it he looked as guilty as if he'd kicked his grandmother. -Philip Marlowe

'Why' and 'How' are words so important they cannot be too often used. -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 03-17-2011 at 12:01 AM.
Tom Schmitz is online now  
post #3 of 7 Old 03-17-2011, 12:20 AM Thread Starter
new
1st Gear
 
Join Date: Jul 2009
Posts: 30
Dont know what size of jet I'm at work i think it a 165 jet not sure was getting 50 MPG before. The kit has many jets just was seeing if anyone had better luck picking a jet.
new is offline  
 
post #4 of 7 Old 03-17-2011, 12:53 AM
Pretty in Pink, dunno why
 
Tom Schmitz's Avatar
 
Join Date: Feb 2009
Location: Redondo Beach
Posts: 7,611
Garage
new-

I don't have a conversion for a 165. My table shows a 164 and 166. But no matter; a 164 is equivalent to a Keihin 182.5. Of course, without know the diameter and taper of a DJ needle (you're using a DJ needle, I presume) we can't really say anything about the size of the jet.

A jet is like a cat in that you don't pick a jet, it picks you. For your engine, there is a jet and needle position that is right - it will deliver the appropriate Air/Fuel Ratio. You need some way of ascertaining what your AFR. Probably the simplest is to read the plug. A plug from a rich running engine will be sooty and black. A lean engine will have a whitish and sorta glazed looking plug. An engine that is running at the right ratio will have a tan appearance.

Now, if you were getting 50 mpg before, I'd be willing to bet you were running a bit lean (unless you weigh about 125 pounds). My suggestion would be to go from your mid 160s jet down to something on the order of a mid 150s. That should be about 10% smaller in diameter. Take it out for a run and get yourself moving along in third or fourth at mid throttle for a good mile or so. Pull in the clutch and kill the engine. Pull the plug and look at it. In truth, if a roadside plug pull on the KLR is too big of a pain, just take it out for a good ride and come home and check the plug. Just don't let it idle for long when you get it home. If you have a tan plug, all's well. If it's whitish, change it immediately for a larger jet before you do any damage from running too lean.

T

Tom [email protected]

The kid poured him another straight rye and I think he doctored it with water down behind the bar because when he came up with it he looked as guilty as if he'd kicked his grandmother. -Philip Marlowe

'Why' and 'How' are words so important they cannot be too often used. -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 03-17-2011 at 01:03 AM.
Tom Schmitz is online now  
post #5 of 7 Old 03-17-2011, 03:02 PM
4th Gear
 
Spec's Avatar
 
Join Date: Apr 2010
Location: Gateway to Death Valley!
Posts: 1,928
Quote:
Originally Posted by new View Post
Dont know what size of jet I'm at work i think it a 165 jet not sure was getting 50 MPG before. The kit has many jets just was seeing if anyone had better luck picking a jet.

Stock the KLR is lean on the low speed circuits (pilot and needle) and rich on the main. I wouldn't go any larger on the main unless you've made intake/engine mods.

If you went larger on the main and stay >3/4 throttle for lengths of time yea your milage will drop.

Here's a good basic page: Motorcycle Carburetor Theory 101

Here's a more in depth CV carb resource: Keihin CVK40

No eye has seen, no ear has heard, no mind has conceived what God has prepared for those who love him. 1 Cor 2:9
Spec is offline  
post #6 of 7 Old 03-17-2011, 05:47 PM
Pretty in Pink, dunno why
 
Tom Schmitz's Avatar
 
Join Date: Feb 2009
Location: Redondo Beach
Posts: 7,611
Garage
Quote:
Originally Posted by Spec View Post
...Here's a good basic page: Motorcycle Carburetor Theory 101...
Oh, dat a good page.

Thanks Spec!

T

Tom [email protected]

The kid poured him another straight rye and I think he doctored it with water down behind the bar because when he came up with it he looked as guilty as if he'd kicked his grandmother. -Philip Marlowe

'Why' and 'How' are words so important they cannot be too often used. -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem
Tom Schmitz is online now  
post #7 of 7 Old 03-17-2011, 06:52 PM
Neutral
 
Join Date: Mar 2011
Location: Massachusetts
Posts: 1
FYI re: Dynojet

FYI: Don't try getting a jet size off of your Dynojet kit's jet's. Dynojet uses a proprietary coding system to prevent people from duplicating their kits. The numbers on their jets and needles don't correspond to any standards.
motorep 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



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