2018 KLR650 Jetting Question - 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.

 8Likes
 
LinkBack Thread Tools
Old 11-14-2019, 03:16 PM Thread Starter
Neutral
 
Rick Hall's Avatar
 
Join Date: Nov 2019
Location: Virginia Beach
Posts: 6
2018 KLR650 Jetting Question

Hey folks. I just installed the 6 Sigma jet kit on a 2018 KLR650. Seems great except that it bogs terribly at 4500 RPM at wide open throttle. The instructions recommend increasing the main jet if lean at wide open throttle but it didn't really detail at what RPM range. However, it did say if lean below 4000 RPM to mess around with the needle and float level. It seems to pull great up to 4500. I can only assume that the bogging that starts at 4500 RMP at WOT is a lean condition but not sure. I only want to tear into this thing one more time if possible so I wanted to ask you what I should adjust next.

Here’s the current set up:

Needle – Raised with 2 metal shims
Main – 155 (changed from 145)
Pilot – 45 (changed from 40)
Mixture – 2.5 out (changed from 1.5)
Slide – Drilled with #30 bit provided
Slide spring – cut off one loop
Airbox – L-shaped mod on top, stock filter
Exhaust – DG open performance pipe
Elevation – none (Virginia Beach)

Thanks in advance!! -Rick
Rick Hall is offline  
Sponsored Links
Advertisement
 
Old 11-14-2019, 03:36 PM
4th Gear
 
Join Date: Aug 2010
Location: Kelowna, B.C.
Posts: 2,444
Hmmm; hard to say as I don't have any experience with that kit and since everything depends on the needle, what works with the KLX needle that most use (or even the DJ needle) may not work for you.

Plug chops don't work well with today's fuel.....so you're kinda shooting in the dark here. an O2 bung and sensor or using a standard setup that many people have used before with documented success would seem to be the solutions. Maybe call the supplier and see if they made their own needle or where it came from.

One thing I'd mention is that a #30 bit is bigger than the 1/8" drill bit that Dynojet supplies AND according to several gurus, 1/8" has been known to cause a bog......which is why Eaglemike recommends 7/64ths when using his KLX jet kit. Since drilling the slide doesn't affect jetting anyhow, only throttle response, I didn't bother on my two.

Dave
DPelletier is online now  
Old 11-14-2019, 03:47 PM Thread Starter
Neutral
 
Rick Hall's Avatar
 
Join Date: Nov 2019
Location: Virginia Beach
Posts: 6
Quote:
Originally Posted by DPelletier View Post
Hmmm; hard to say as I don't have any experience with that kit and since everything depends on the needle, what works with the KLX needle that most use (or even the DJ needle) may not work for you.

Plug chops don't work well with today's fuel.....so you're kinda shooting in the dark here. an O2 bung and sensor or using a standard setup that many people have used before with documented success would seem to be the solutions. Maybe call the supplier and see if they made their own needle or where it came from.

One thing I'd mention is that a #30 bit is bigger than the 1/8" drill bit that Dynojet supplies AND according to several gurus, 1/8" has been known to cause a bog......which is why Eaglemike recommends 7/64ths when using his KLX jet kit. Since drilling the slide doesn't affect jetting anyhow, only throttle response, I didn't bother on my two.

Dave
Thanks for the quick reply Dave. I have an email into 6 Sigma. Everyone says they have great support but I always like to hear all opinions on these things. I'll see what they come back with. BTW, what's an 02 Bung and sensor?
Rick Hall is offline  
 
Old 11-14-2019, 04:15 PM
4th Gear
 
Join Date: Aug 2010
Location: Kelowna, B.C.
Posts: 2,444
Air fuel oxygen/ratio sensor to tune jetting by measuring optimal mixture conditions; https://www.summitracing.com/parts/i...iABEgL4ffD_BwE

a bung is the pce that you weld to the exhaust pipe in order to take the reading;
DPelletier is online now  
Old 11-14-2019, 05:38 PM
2nd Gear
 
Join Date: Oct 2019
Posts: 183
Quote:
Originally Posted by DPelletier View Post
Air fuel oxygen/ratio sensor to tune jetting by measuring optimal mixture conditions; https://www.summitracing.com/parts/i...iABEgL4ffD_BwE

Wow! I was thinking cool. A tool I could use to check my setup after upgrading my engine, but that’s about a third of what a FI kit would cost. The FI kit can already log this data, so I’d probably just buy it instead.

Unless ... are there any less expensive meters or logging kits? An O2 sensors not that expensive from what I recall, so any good DIY methods available?



Sent from my iPhone using Tapatalk
ILove2Ride2Wheels is offline  
Old 11-14-2019, 08:00 PM
Pretty in Pink, dunno why
 
Tom Schmitz's Avatar
 
Join Date: Feb 2009
Location: Redondo Beach
Posts: 7,662
Garage
Quote:
Originally Posted by Rick Hall View Post
Hey folks. I just installed the 6 Sigma jet kit on a 2018 KLR650. Seems great except that it bogs terribly at 4500 RPM at wide open throttle. The instructions recommend increasing the main jet if lean at wide open throttle but it didn't really detail at what RPM range. However, it did say if lean below 4000 RPM to mess around with the needle and float level. It seems to pull great up to 4500. I can only assume that the bogging that starts at 4500 RMP at WOT is a lean condition but not sure. I only want to tear into this thing one more time if possible so I wanted to ask you what I should adjust next.

Here’s the current set up:

Needle – Raised with 2 metal shims Well, yeah, that is OK depending on what the shims are. If they are #4 washers it would be right.
Main – 155 (changed from 145) If that is a Keihin jet, hell no. The stock needle, which I assume you have, has a severe taper at the tip which causes it all to go stupid rich with a stock jet. A 155 has no business being in any KLR. If it is not a Keihin jet then we need to know what the diameter of the jet is. It would also throw the idea of shimming the needle into a cocked hat.
Pilot – 45 (changed from 40) Nope. A 42 is about as big as you'd ever need.
Mixture – 2.5 out (changed from 1.5) The number of turns out on the needle is a rough, ballpark thing. Better to use the 'idle-increase' method to determine proper idle mixture, especially with a gi****inghugic idle jet in there.
Slide – Drilled with #30 bit provided Who came up with that? Even the Harley guys don't go over an 1/8". As @dpelletier sis, 7/64" is the right diameter. A number 30 drill is 38% larger in cross-section than a 7/64". That ain't right.
Slide spring – cut off one loop Good god.
Airbox – L-shaped mod on top, stock filter Yeah
Exhaust – DG open performance pipe Yeah
Elevation – none (Virginia Beach) OK

Thanks in advance!! -Rick
Who is this 6 Sigma outfit? Do they have any idea what 6 sigma means? This is the most bizarre recipe for a CVK40 set-up I have ever seen.

I hate to be a dick (not really, it comes pretty naturally) but here's what I'd do with that set-up.

Get a KLX needle kit from Schnitz Racing or Eagle and use the directions. You'll need to fix the hole in the slide, though, or get a new slide (the Harley slide is affordable). JB the hole up nice and neat and drill a new hole, going with nothing larger than 7/64. You should get a new spring, too. Never been a fan of that willie-nillie spring cutting idea.
DPelletier and Norton 850 like this.

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -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; 11-14-2019 at 08:14 PM.
Tom Schmitz is online now  
Old 11-14-2019, 08:36 PM
OverDrive
 
Join Date: Nov 2009
Location: Lander, Wyoming
Posts: 5,701
I'll suggest that the OP pinched the throttle slide Diaphragm, and it won't run correctly until it is replaced, regardless of jetting.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
pdwestman is online now  
Old 11-14-2019, 09:14 PM Thread Starter
Neutral
 
Rick Hall's Avatar
 
Join Date: Nov 2019
Location: Virginia Beach
Posts: 6
1

Quote:
Originally Posted by Tom Schmitz View Post
Who is this 6 Sigma outfit? Do they have any idea what 6 sigma means? This is the most bizarre recipe for a CVK40 set-up I have ever seen.

I hate to be a dick (not really, it comes pretty naturally) but here's what I'd do with that set-up.

Get a KLX needle kit from Schnitz Racing or Eagle and use the directions. You'll need to fix the hole in the slide, though, or get a new slide (the Harley slide is affordable). JB the hole up nice and neat and drill a new hole, going with nothing larger than 7/64. You should get a new spring, too. Never been a fan of that willie-nillie spring cutting idea.

Well Tom, that was inspiring! LOL. I did 24 years in the Navy so, I can tolerate someone who is a dick, but knowledgeable! Your input is helpful. I'll wait and see what the 6 Sigma guys say but yeah, the KLR knowledge base would take precedence. A friend who had great results with one of their kits recommended them.

If you don't mind, please share your preferred set up with me.
Rick Hall is offline  
Old 11-14-2019, 10:29 PM
Pretty in Pink, dunno why
 
Tom Schmitz's Avatar
 
Join Date: Feb 2009
Location: Redondo Beach
Posts: 7,662
Garage
Mine is the tried and true KLX set-up and is a recipe that seems to work for the vast majority of KLRs. Sometimes the recipe will require a bit of tweaking by doing a half-clip's worth of needle adjustment with a #4 washer.

Begin with a KLX needle with the clip set at the second position down.

My carb, an '09, came with a 145 main jet. I have 1" holes drilled in the airbox and a modified airbox door. I use a GSXR750 pipe, which is fairly open. I dropped the main jet down to a 142.5. That gives me an air/fuel ratio of about 13:1 from idle to near redline, as measured with an 02 meter.

I had some excessive popping on decel and changed the idle jet to a #42 to get rid of that.

I did drill the slide to 7/64" but I'm not convinced that it is worthwhile. The CVK40 depends on the vacuum to raise the slide; the hole that is being drilled is essentially a transfer port that allows air to come out of the upper chamber as the vacuum pulls the slide up. You can see how, if that port is too large, it could defeat the vacuum to a degree and prevent the slide from rising (or, at the very least, the slide would flutter). That's why drilling that hole too large causes bogging.

As @pdwestman pointed out, a pinched diaphragm has the same effect because it defeats the vacuum and the slide won't rise completely.

Since it is vacuum that is raising the slide, rather than a direct pull from the cable, there is a lag. This is the throttle response that drilling the hole is supposed to improve. If I were drag racing the KLR or if I were the type that goes WOT off of every green light I might think that quicker throttle response is really important. But I'm a fat, tired, old man and I don't do that shit. Since I don't slam the throttle open I don't notice the throttle lag. I don't think most people do, either, but they get caught up in "doing all I can to get as much power out of it as I can" even though they've no use for it. That's why I question how worthwhile it is.

To recap, a KLX needle with the clip in the second groove, a 142.5 main jet, 42 idle jet, holed air box and a freer-flowing exhaust. Drilled slide, meh.
DPelletier likes this.

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -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; 11-14-2019 at 10:32 PM.
Tom Schmitz is online now  
Old 11-14-2019, 10:46 PM
5th Gear
 
Join Date: Jan 2011
Posts: 4,437
Quote:
Originally Posted by Tom Schmitz View Post
You should get a new spring, too. Never been a fan of that willie-nillie spring cutting idea.
I, too, remain skeptical of the slide spring coil-clipping exercise. While the offset, or pre-load of the spring is changed upon coil-clipping, the shorter spring is stiffer (has a higher rate) than when of stock length (number of coils). Spring stiffness (or rate): Force divided by deflection, or something, IIRC.

I know; I know; the concept may seem counter-intuitive; but, conventional wisdom holds cutting a circular spring's coils results in additional force required for the same deflection, compared with the spring's original number of coils.

Any increase in throttle response from coil clipping may result from the change in offset/pre-load; not from the consequent stiffening of the spring, seems to me.

DISCLAIMER: I may be in error!

“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre
Damocles is online now  
Sponsored Links
Advertisement
 
 

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



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