The Sportster and Buell Motorcycle Forum - The XLFORUM®
 

Go Back   The Sportster and Buell Motorcycle Forum - The XLFORUM® > SPORTSTER MOTORCYCLE FORUM > Sportster Motorcycle Intake and Exhaust > Sportster Motorcycle Air intake, Carburetor, EFI, Fuel, and Exhaust
XLF Blogs XLF Arcade XLF Disclaimer/Privacy Statement/Terms Of Use

Notices

Sportster Motorcycle Air intake, Carburetor, EFI, Fuel, and Exhaust Problems, advice and/or how tos for Sporster and Buell motorcycle carburators, Electronic Fuel Injection (EFI), Air Intake, Fuel and Exhaust.

Active Threads
0 Ironhead engine problem?
Last Post: Whitewalls
Posted On: 35 Minutes Ago
Replies: 6
Views: 113
0 1100 bathtub heads on a 883?
Last Post: Tomcatt
Posted On: 2 Hours Ago
Replies: 1
Views: 59
0 Keep & Kill
Last Post: Crusty
Posted On: 2 Hours Ago
Replies: 25,426
Views: 1,487,681
0 900 clutch in a 1000 engine Strociek
Last Post: Ferrous Head
Posted On: 4 Hours Ago
Replies: 6
Views: 225
0 a definitive sportster chain conversion pros and cons list
Last Post: Bluto
Posted On: 6 Hours Ago
Replies: 13
Views: 214
0 North central Mass
Last Post: shanneba
Posted On: 6 Hours Ago
Replies: 4
Views: 92
0 04 Sportster refurb and build.
Last Post: JimVonBaden
Posted On: 7 Hours Ago
Replies: 24
Views: 1,103
0 Official XL Forum Random Image Thread (NO NUDITY!)
Last Post: brucstoudt
Posted On: 7 Hours Ago
Replies: 52,429
Views: 8,841,908
0 KT - 2021 - You're In It Now
Last Post: sportsterpaul
Posted On: 8 Hours Ago
Replies: 75
Views: 14,094
0 1968 ex barn dweller thread
Last Post: davixlrtt
Posted On: 9 Hours Ago
Replies: 204
Views: 20,659
0 Hot Rods, Rat Rods, and Customs.
Last Post: Stairman
Posted On: 10 Hours Ago
Replies: 4,808
Views: 952,491
0 Hottie of the day, no nudity.
Last Post: Stairman
Posted On: 11 Hours Ago
Replies: 32,935
Views: 3,866,294
0 Setting Timing, 1964 & Earlier Mag
Last Post: needspeed
Posted On: 12 Hours Ago
Replies: 32
Views: 16,221
0 never mind
Last Post: IXL2Relax
Posted On: 13 Hours Ago
Replies: 300
Views: 57,263
0 XR1000 black and orange pics?
Last Post: 84rzv500r
Posted On: 13 Hours Ago
Replies: 6
Views: 438
0 my sunday driver...
Last Post: 84rzv500r
Posted On: 13 Hours Ago
Replies: 132
Views: 26,182
0 XR1000 Pushrod Tube Leaks
Last Post: KRTTXRTT
Posted On: 14 Hours Ago
Replies: 1
Views: 423
0 This is gonna hurt.
Last Post: cal43
Posted On: 17 Hours Ago
Replies: 9,068
Views: 2,117,177
0 video & pics
Last Post: cal43
Posted On: 17 Hours Ago
Replies: 556
Views: 57,250
0 1997 Air Cleaner Backplate
Last Post: rathawk
Posted On: 17 Hours Ago
Replies: 2
Views: 136
0 Hot Chicks on Hot Bikes
Last Post: cal43
Posted On: 20 Hours Ago
Replies: 12,598
Views: 2,971,909
0 Dining out
Last Post: sportsterpaul
Posted On: 1 Day Ago
Replies: 1
Views: 113
0 1983 Roadster
Last Post: RicThompson
Posted On: 1 Day Ago
Replies: 59
Views: 3,927
0 Happy Thanksgiving
Last Post: Crusty
Posted On: 1 Day Ago
Replies: 5
Views: 151
0 Strociek Project Help Needed
Last Post: Ferrous Head
Posted On: 1 Day Ago
Replies: 24
Views: 844
0 Which Sportster car costs about 2000$?
Last Post: NLXL
Posted On: 1 Day Ago
Replies: 7
Views: 339
0 Allegheny National Park III
Last Post: sprink
Posted On: 1 Day Ago
Replies: 17
Views: 351
0 What's your opinion on windshields?
Last Post: mikethebike61
Posted On: 1 Day Ago
Replies: 1,281
Views: 255,491
0 MId-range breaking up under acceleration
Last Post: gary59
Posted On: 1 Day Ago
Replies: 16
Views: 767
5 35mm Showa Installation Procedure? Tighten Sequence?
Last Post: BigMek
Posted On: 1 Day Ago
Replies: 3
Views: 134
More...
Members Birthdays
excel50 (80), blazer95 (71), mycle1000, Barryn37 (60), QBALL (60), paulieb (59), cfranz (48), BMXATV (47), ravyn3 (42), Texas_Wild, hillpope (39)
Reply
 
Share Thread Tools Display Modes
  #1  
Old 21st October 2021
sml1226 sml1226 is offline
Flat Track Champion
 
Join Date: Apr 2015
Posts: 648
Sportster/Buell Model: XL1275R
Sportster/Buell Year: 2004
sml1226 has disabled reputation
Default HSR idle mixture screw

Hey guys. I have an HSR42 that I’ve never been able to get right. I stuck an O2 sensor on to check AFR here recently and it doesn’t seem to want to move any while turning the air screw. I’m not really sure if it’s always been like this or not but I can’t really tune the rest of the carb if the idle is never right.

The needle, needle jet, main, etc shouldn't be affecting me here, should they? I’ve had a 20 and a 22.5 in there so far and both seem to settle right around 13:1. I can get it to go richer, but even there, not a ton. I think it hit 11.5:1 before it stumbled.

So I guess the first question is, is there anything that would lead to the screw being largely useless? I can’t see anything blocking the air passages. The air jet is a blank on these. The choke plunger, as far as I can tell, is fully seated. An air leak somewhere would have the opposite issue.

I can try a 17.5 jet too, as I do have one, but I’d still expect the AFR to move even if the jet were too large.

Any other suggestions?
Reply With Quote
  #2  
Old 21st October 2021
Fivecats's Avatar
Fivecats Fivecats is offline
XL FORUM TEAM MEMBER
 
Join Date: Jan 2011
Location: Kelso, Washington
Posts: 335
Sportster/Buell Model: XLCH
Sportster/Buell Year: '68
Sportster/Buell Model #2: FXR
Sportster/Buell Year #2: '89
Other Motorcycle Model: R50/5
Other Motorcycle Year: '73
Reputation: 412401
Fivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond reputeFivecats has a reputation beyond repute
Default

Never touched one, but maybe this will help.

https://r.search.yahoo.com/_ylt=AwrV...ZMtGKc5MNZa.Q-
Reply With Quote
  #3  
Old 21st October 2021
sportsterpaul's Avatar
sportsterpaul sportsterpaul is offline
XL FORUM LIFE MEMBER
 
Join Date: Jan 2009
Location: In a swamp/Michigan
Posts: 15,842
Sportster/Buell Model: XL1460C
Sportster/Buell Year: 2000
Sportster/Buell Model #2: XL1200R
Sportster/Buell Year #2: 2006
Other Motorcycle Model: XL1200R
Other Motorcycle Year: 2004
Reputation: 15268881
sportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond reputesportsterpaul has a reputation beyond repute
Default

Just a thought, the choke plunger on that if it’s the modified H.D. Cable can hang up and that would give you a richer mixture. The Mikuni cable, is a much better alternative and recommended.
__________________
I.B.A.#26543,

Dads words of wisdom:”behave and if you can’t behave don’t get caught!”

The XL Forum Sportsterpedia:
http://sportsterpedia.com/doku.php/start
Reply With Quote
  #4  
Old 21st October 2021
Tomcatt Tomcatt is offline
Dazed & Confused
 
Join Date: Feb 2019
Location: Never Never Land
Posts: 2,486
Sportster/Buell Model: XL1200C
Sportster/Buell Year: 2017
Other Motorcycle Model: BMW R9T
Other Motorcycle Year: 2015
Reputation: 3105395
Tomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond repute
Default

Quote:
Originally Posted by sml1226 View Post
Hey guys. I have an HSR42 that I’ve never been able to get right.

Any other suggestions?
Are you turning the screw the right direction? On the HSR 42 it's an air screw. Turning it in richens the mixture, out is leaner. The usable range is normally between 1/2 and 2 1/2 turns out. The off idle transition is frequently best with a pilot jet that has a best idle with the screw 1 - 1 1/2 turns out.

The other thing that comes to mind is that like having the throttle blade open too far on the CV carbs, you can have the slide lifted too high on a slide type and have it pulling fuel thru the transfer ports.

Make sure you have enough ignition advance at idle, 12 - 15 degrees, that helps it idle with less slide opening.

Idle AFR is interesting but best idle is with the mixture screw setting that gives the highest manifold vacuum, or the lowest MAP. I would expect "best idle" AFR's to be in the lowish to mid 12's.
__________________
2017 XL1200C in SE Wisconsin, USA
Reply With Quote
  #5  
Old 22nd October 2021
sml1226 sml1226 is offline
Flat Track Champion
 
Join Date: Apr 2015
Posts: 648
Sportster/Buell Model: XL1275R
Sportster/Buell Year: 2004
sml1226 has disabled reputation
Default

Mikuni cable is on there (yes, Mikuni spring and plunger too). I never liked the Keihin cable on these carbs prior to the swap. As far as I can tell, that’s good.

And yeah, I know it’s an air screw. I’m not so much trying to tune it for a specific AFR as I am confused by the lack of change as I do turn the screw. But tuning it by MAP is something I hadn’t thought of and if I can ever get it working, I’ll be sure to run my monitor and look at that while setting it. As for the slide height at idle, that was honestly my big concern. The AFR wouldn’t do much with the screw if it’s already on the needle jet. The slide is pretty low as is, but I can’t say for certain on that one. I’m not entirely sure where it starts pulling from that circuit on these just by looking. It is as low as I can get it to idle, but I suppose if it’s that much too lean on the pilot, I could potentially have turned the adjuster in enough to lift it past the idle circuit height.

And I’d have to check on the ignition. I haven’t paid that much attention here.

Thanks for the suggestions though. I’ll see what my ignition map looks like if it needs any tweaking around idle and see if going richer on the pilot lets me lower that slide any more than it is now.
Reply With Quote
  #6  
Old 4 Weeks Ago
bustert's Avatar
bustert bustert is offline
XL FORUM TEAM MEMBER
 
Join Date: Jul 2008
Posts: 10,672
Sportster/Buell Model: 1200s
Sportster/Buell Year: 2001
Sportster/Buell Model #2: xlch
Sportster/Buell Year #2: 1974
Reputation: 3365312
bustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond reputebustert has a reputation beyond repute
Default

i have a question, are you using the correct heated sensor?
a sensor that cannot maintain a set temp is a poor choice as the O2's will be off. also remember how the engine is fueled, it is not a steady state stream and each cyl can/will effect the other.
Reply With Quote
  #7  
Old 4 Weeks Ago
sml1226 sml1226 is offline
Flat Track Champion
 
Join Date: Apr 2015
Posts: 648
Sportster/Buell Model: XL1275R
Sportster/Buell Year: 2004
sml1226 has disabled reputation
Default

I would assume it’s heating properly, but yes it’s a heated wideband sensor feeding a gauge designed for that particular sensor. I forget the model but it’ll run a short little “heat” cycle at the gauge before reading the ratios.

And absolutely. The idle is probably going to be the least reliable AF number I see, but I still expect movement of the number as I turn that screw. That was the biggest concern, and my only thought that made sense was that somehow I wasn’t running on the idle circuit at all. I haven’t had a chance to make changes and see if they help yet, but unless something’s screwy in the carb, that’s still where I’m leaning.
Reply With Quote
  #8  
Old 4 Weeks Ago
Tomcatt Tomcatt is offline
Dazed & Confused
 
Join Date: Feb 2019
Location: Never Never Land
Posts: 2,486
Sportster/Buell Model: XL1200C
Sportster/Buell Year: 2017
Other Motorcycle Model: BMW R9T
Other Motorcycle Year: 2015
Reputation: 3105395
Tomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond reputeTomcatt has a reputation beyond repute
Default

Quote:
Originally Posted by sml1226 View Post
...my only thought that made sense was that somehow I wasn’t running on the idle circuit at all. I haven’t had a chance to make changes and see if they help yet, but unless something’s screwy in the carb, that’s still where I’m leaning.
One way that happens is because the slide lifted too far to keep it idling because your idle mixture is way off or you've got too little ignition advance at idle.

This is where a vacuum or MAP gauge really helps. You adjust the air (mixture) screw to get the highest vacuum / lowest MAP. That normally raises your idle speed so you lower the slide to bring your idle speed back down and repeat the process as the lowered slide will change how the idle circuit / transfer ports pull fuel. When the transfer ports are pulling fuel the effect of the air screw is diminished.

It's kinduva a dog chasing its' tail process but that's how you get it right.

You also need to keep track of how many turns out the air screw is and change the pilot jet size so best idle is with the screw 1 - 1 1/2 turns out.

What cams are you running?
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
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 Off

Forum Jump



All times are GMT +1. The time now is 07:02.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
XL Forum® - Linson Media LLC