B12 jetting problem, BST40 - Custom Fighters - Custom Streetfighter Motorcycle Forum

Go Back   Custom Fighters - Custom Streetfighter Motorcycle Forum > Technical Section > Making Power

Making Power Anything to do with fabricating and modifying engines, carbs, ignition, etc. goes in here.

CustomFighters.com Streetfighter Motorcycle Forum > B12 jetting problem, BST40

Reply
 
Thread Tools
Old Streetfighter Motorcycle Forum Post 08-03-2017, 07:20 PM   #1
jacekdominik87
Newbie
Noobie
Local Time: 08:10 PM
Location: Świętokrzyskie [Poland]
Posts: 5
Flip Offs: 0
Flipped Off 0 Times in 0 Posts
jacekdominik87 is a NOOB
Default B12 jetting problem, BST40

Hi.

I ve got a little "jetting problem" in my modified B12
Cant setup good AFR between 2,0k rpm ... 3,75K rpm.
in whole range AFR is what i want, but i can not sel, low-rpm. it's always too rich (something like 9-9,5 afr)
other rpm/afr looks like:
idle:13
2-4k 9,5
4-redline 12..11,6


At the beginning i need to write something, to eliminate many questions:
Engine: B12, K2
camshaft: gixx 750 or 1100, non stock
Airbox: no airbox KN 2x2
Exhaust: full open, "racing type",
Head: stock, but modified (polished)
ignition module: stock, but TPS sensor are "emulated" on 50-70 percent open throttle.
spark plugs: iridium denso

I've got installed AFR analyzer on board with wideband bosh lsu 4,2 sensor.

Carbs:
few words... Carbs are almost new. i need to find a lot of parts in something around 3 years to get it top shape.
To build them i need do buy 5-6 another carbs, and chose best parts (if i cant find new, or there are to much expensive).
I try MANY settings. something like 50 times in and out in 2 years. yes. really.
I've got few useful tools:AFR onboard, few vacuum meters, 4channel industrial thermocouple thermometer, infrared thermometer,
air flow meter, colortune.

body: bst 40
spring: stock, cutted of 2 coils
diaphgram: bst 38, totally new
throttle valve: bst 38. (have got a little bigger "window" but work's like stock bst 40)
Main jet: actually 160
pilot jet: 47,5
Needles: 6zd7, stock 1127 if i good remember.
needle: 5 from top, most richer (3, and 4 gives to lean run on quick throttle open)
float level: "stock" 14,7
emmulsion tube: stock bst 40. i if good remember P-2
pilot screw: -2,5 turn out


So.. the quesion is:
What do you Advice to get lean this low rpm range (2-4k) ?
lower float level ? change emmulsion tube ? maybe one of the dyno jet needles will be useful ?

anyway i answer few questions:
lowering pilot jet, needle setting, main jet - tried this in many options, not good sollution.

ps. sorry for bad english.
jacekdominik87 is offline   Reply With Quote on our streetfighter motorcycle forum

Advertisement
These advertisements only appear for guests, register now for free to remove these ads!
Sponsored Links
Advertisement
 
Old Streetfighter Motorcycle Forum Post 08-03-2017, 10:02 PM   #2
ultimate fighter
Remi's Dad
ultimate fighter's Avatar on CustomFighters.com Streetfighter Motorcycle Forum
I support CustomFighters.com Streetfighter Motorcycle Forum
Local Time: 02:10 PM
Location: bristol, IN
Posts: 17,590
Flip Offs: 1,427
Flipped Off 875 Times in 399 Posts
ultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympus
Supporter of the Streetfighter Build for Charity 
Default Re: B12 jetting problem, BST40

Needles too rich pilot too rich

Possibly different needle taper needed

UF's 2017 winter buildoff MOE POWA
talk about my junk
Quote:
Originally Posted by yantosh View Post
CB is cool as fuck , proper old skool kick your cunt in for looking at it funny
ultimate fighter is offline   Reply With Quote on our streetfighter motorcycle forum
These people High Fived ultimate fighter!
Old Streetfighter Motorcycle Forum Post 08-04-2017, 08:03 AM   #3
CK 187
CAPTAIN AWESOME®

CK 187's Avatar on CustomFighters.com Streetfighter Motorcycle Forum
I support CustomFighters.com Streetfighter Motorcycle Forum
Local Time: 02:10 PM
Location: Now South Carolina (da beach)
Posts: 30,023
Flip Offs: 631
Flipped Off 470 Times in 171 Posts
CK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too much
Default Medal Supporter of the Streetfighter Build for Charity Supporter of the Streetfighter Build for Charity 
Default Re: B12 jetting problem, BST40

I would drop the pilot down a size and try tapered needles
CK 187 is offline   Reply With Quote on our streetfighter motorcycle forum
 
Old Streetfighter Motorcycle Forum Post 08-04-2017, 05:27 PM   #4
jacekdominik87
Newbie
Noobie
Local Time: 08:10 PM
Location: Świętokrzyskie [Poland]
Posts: 5
Flip Offs: 0
Flipped Off 0 Times in 0 Posts
jacekdominik87 is a NOOB
Default Re: B12 jetting problem, BST40

lowering pilot >
i tried this, without good resoult.
When i lower the pilot jet only idle goes down, from 13 to 14..16 depend on jet size, so there is not the sollution. i tried this in few configuration. only "benefit" is hard to set idle at 1250rpm when i lower pilot jet.


lowering needles.
as i sad before, when i quick open throttle (for wheelie example) it goes to lean.
something likie 13-16-13 AFR. in this setting (5 from top) is best throttle response, and everything is good.

What do you think about changing emmulsion tubes ?
Dudes, i REALLY tried almost everithing except emmulsion tubes, and float levels.

anyway, thanks for reply. looking good, but i tried this before.
jacekdominik87 is offline   Reply With Quote on our streetfighter motorcycle forum
Old Streetfighter Motorcycle Forum Post 08-04-2017, 06:32 PM   #5
ultimate fighter
Remi's Dad
ultimate fighter's Avatar on CustomFighters.com Streetfighter Motorcycle Forum
I support CustomFighters.com Streetfighter Motorcycle Forum
Local Time: 02:10 PM
Location: bristol, IN
Posts: 17,590
Flip Offs: 1,427
Flipped Off 875 Times in 399 Posts
ultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympusultimate fighter sits atop olympus
Supporter of the Streetfighter Build for Charity 
Default Re: B12 jetting problem, BST40

ive dealt with this before on the bst carbs.

there's a compromise in a lean pilot causing a rich bog because the jets add fuel before the slide has time to vacuum up.

You dont want to foul during a hot idle and you also dont want to go pig rich in your mid range.

I really don't like tossing out ideas over the internet. It doesn't help that i'm not seeing a plug chop or any other pseudo symptoms.

Plus it may give you a tunnel vision and steer you away from a possible issue.

if you can translate here's some help on correct jetting steps to help really dial it in
http://www.factorypro.com/tech_tunin...m_engines.html

UF's 2017 winter buildoff MOE POWA
talk about my junk
Quote:
Originally Posted by yantosh View Post
CB is cool as fuck , proper old skool kick your cunt in for looking at it funny
ultimate fighter is offline   Reply With Quote on our streetfighter motorcycle forum
Old Streetfighter Motorcycle Forum Post 08-05-2017, 11:43 AM   #6
jacekdominik87
Newbie
Noobie
Local Time: 08:10 PM
Location: Świętokrzyskie [Poland]
Posts: 5
Flip Offs: 0
Flipped Off 0 Times in 0 Posts
jacekdominik87 is a NOOB
Default Re: B12 jetting problem, BST40

guys....

Problem with too rich 2-4K range are also with smaller pilot jet (40 stock, or even lower).
did you read everything i wrote ? i TRIED THIS many times in many configuration.
lowering pilot jet in MY CASE did not lower 2-4K range too much. always is beetween 9-9,5.
if i will "brake" 11,4 it will be finished, but i can't do this.

If anyone want to help, please do not "advise" t get lower pilot jest.
i wrote again.. i tried this and with no good resoult.

BTW. i've got no leaks, every o-rng are brand new, and carb in top shape. everything is shiny etc.
Every test's are doing on road, engine hot, AFR meter on board.

does anyone changed emmulsion tubes when jetting ? any resoult's ?




anyway i will fight with the problem, cecause b12 engine gives a lot of power, and annihilate between 7k and redline :
jacekdominik87 is offline   Reply With Quote on our streetfighter motorcycle forum
Old Streetfighter Motorcycle Forum Post 08-05-2017, 12:03 PM   #7
Streetfighterkz
Capt Oblivious
CF Pimp
Streetfighterkz's Avatar on CustomFighters.com Streetfighter Motorcycle Forum
I support CustomFighters.com Streetfighter Motorcycle Forum
Local Time: 01:10 PM
Location: St. Charles (StL), MO
Posts: 2,962
Flip Offs: 0
Flipped Off 11 Times in 7 Posts
Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!Streetfighterkz is an amazingly helpful member with a good attitude!
Default Re: B12 jetting problem, BST40

I could be way off so excuse me if I am, but I thought I remember the older Gsxr's (and maybe Bandits) having troubles with the emulsion tube orifice ovaling. It caused goofy carb symptoms. May wanna try checking out Old Skool Suzuki or even Gixxer.com.

Hope you get it figured out.

Later, Doug

‘74 Kawasaki H1-500 Project
‘76 Kawasaki Kz900 'Strip-fighter Project
‘77 Kawasaki Kz1000
‘78 Kawasaki Kz1000 Project
'80 Cx500 Cafe/Brat Project
‘83 Kawasaki Gpz750 (Turbo Converted) Project
Streetfighterkz is online now   Reply With Quote on our streetfighter motorcycle forum
This user High Fived Streetfighterkz!
Old Streetfighter Motorcycle Forum Post 08-05-2017, 02:08 PM   #8
CK 187
CAPTAIN AWESOME®

CK 187's Avatar on CustomFighters.com Streetfighter Motorcycle Forum
I support CustomFighters.com Streetfighter Motorcycle Forum
Local Time: 02:10 PM
Location: Now South Carolina (da beach)
Posts: 30,023
Flip Offs: 631
Flipped Off 470 Times in 171 Posts
CK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too muchCK 187 plays with their repper too much
Default Medal Supporter of the Streetfighter Build for Charity Supporter of the Streetfighter Build for Charity 
Default Re: B12 jetting problem, BST40

Quote:
Originally Posted by jacekdominik87 View Post
guys....

did you read everything i wrote ? i TRIED THIS many times in many configuration.

If anyone want to help, please do not "advise" t get lower pilot jest.
i wrote again.. i tried this and with no good resoult.

consider yourself unadvised!
CK 187 is offline   Reply With Quote on our streetfighter motorcycle forum
Old Streetfighter Motorcycle Forum Post 08-05-2017, 07:05 PM   #9
jacekdominik87
Newbie
Noobie
Local Time: 08:10 PM
Location: Świętokrzyskie [Poland]
Posts: 5
Flip Offs: 0
Flipped Off 0 Times in 0 Posts
jacekdominik87 is a NOOB
Default Re: B12 jetting problem, BST40

Quote:
Originally Posted by Streetfighterkz View Post
the older Gsxr's (and maybe Bandits) having troubles with the emulsi on tube orifice ovaling. It caused goofy carb symptoms.
Later, Doug
thanks bro. I will try to find some information.
Quote:
Originally Posted by ultimate fighter View Post
if you can translate here's some help on correct jetting steps to help really dial it in
http://www.factorypro.com/tech_tunin...m_engines.html
Also thanks for that ! very good text.

Unfortunately my oxygen sensor died few day's ago and i can't do good test on the road,
but in this moment i will go something like this:

A) lower fuel level, 1 or even 2 mm to see what really happend. if there is no good resoult so try next:

B) back to stock fuel levels, and modify just a little emmulsion tubes. i thinking about use a thermo-shrink tubes to cover part of holes. probably half of them. if this really work i will do few experiments, how many holes covered is best for me. If it will works i just solder holes and be happy. Normally i will change the emmulsion tube to different model, but in Poland we have got a lot of problems to find that type of parts, or else if you find a part you need to pay as a piece of gold.

C) if previous steps did not work (but i hope it will) i will change needle to another profile.
ive got 6ZD7 and 6ZD16, one of them looks like a real needle second like nail. now i've got installed those "needle type", but maybe those "nail" work better. PS. previously i wrote it was 6zd13 but i had check just a second ago, and it is 6zd13. anyway, one rich one lean type.



PS. If anyone would like to get much more power from stock b12 just like me try to do some experiments with ECU. non-stock ignition advance make engine more aggresive.
BTW, maybe you will advise wich stock ECU from any bike (of course with 2 pair of coils and wasted spark) can be easily modified and programmable ? I don't want to use stand alone computers because its to expensive for me, and i just need to modify ignition advance, nothing else. I know i can make it "mechanically", making bigger holes and twist just a little, but it moves whole range in constant degree. much more comfortable option (what i had done) is emulate TPS by 2 pair of resistors making voltage divider, and ecu "think" the throttle is now for example 75% opened and use values for it from the table.
Anyway in B12 K1 K2 (and others just before 1250) ecu had signals from gearbox and kill some power in 2-3-4 gear. this is not good. it can be fixed by emulation of signals from gearbox sensor. i will do this permanently after 2-4k probmlem will be fixed, or else i use temporary old ecu from gixx750 of 1127, but i really would like to program whole range of rpm and ignition advance by my own.
jacekdominik87 is offline   Reply With Quote on our streetfighter motorcycle forum
Old Streetfighter Motorcycle Forum Post 08-07-2017, 02:46 PM   #10
FrenchFries
GURU
CF Addict
Local Time: 01:10 PM
Posts: 2,177
Flip Offs: 0
Flipped Off 1 Time in 1 Post
FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!FrenchFries is an amazingly helpful member with a good attitude!
Default Re: B12 jetting problem, BST40

Those bst40 are known for being a nightmare to get tuned right... You should just ship them to me and I will send you a set of bst36ss to put back on there.
FrenchFries is offline   Reply With Quote on our streetfighter motorcycle forum
Reply

  Custom Fighters - Custom Streetfighter Motorcycle Forum > Technical Section > Making Power

Bookmarks

Thank you for viewing B12 jetting problem, BST40 in the Making Power section of our streetfighter motorcycle forum. I hope you found it useful!


Thread Tools

Forum Jump

Making Power - B12 jetting problem, BST40 on Custom Fighters Streetfighter Motorcycle Forum

All times are GMT -4. The time now is 02:10 PM.



Powered by vBulletin Version 4.20
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.