Contact Overland Solutions for all your custom modifications and setup for overland travel.               Discover the extraordinary with Compass Expeditions.

Go Back   The HUBB > Technical, Bike forums > BMW Tech
“unscrew both regulating screws evenly approx 3/4 turns.” “unscrew both regulating screws evenly approx 3/4 turns.”
Register FAQ Calendar Search Today's Posts Mark Forums Read

BMW Tech BMW Tech Forum - For Questions specific and of interest to BMW riders only. Questions comparing which bike is best etc go in the "Which Bike" forum.
With more than 58 destinations worldwide, Edelweiss Bike Travel is Number 1 in guided motorcycle tours!
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 13 May 2011
Registered Users
Veteran HUBBer
  
Join Date: Feb 2002
Location: Coimbra, Portugal
Posts: 277
“unscrew both regulating screws evenly approx 3/4 turns.”
R100GS

Why does everybody set the mixture screws more then is stated in the manual?

The manual clear states “unscrew both regulating screws evenly approx 3/4 turns.”

I normally set my carbs accordingly to this but I fear that running too “lean” I could damage the engine….

besides the additional power is there any reason to run richer that what is stated in the manual?

What am I missing?
__________________
bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R100 GS
Reply With Quote
  #2  
Old 13 May 2011
Registered Users
HUBB regular
  
Join Date: Mar 2007
Location: Sussex, UK
Posts: 84
I'm no bimmer expert but I know my way round an engine so I'll try and help out here until someone else jumps in.

A richer idle mixture will typically give you better throttle response off idle - open the throttle from idle and the engine will respond faster. However it'll also give you worse exhaust emissions (more carbon monoxide, more unburnt hydrocarbons) which is why the standard idle mixture is usually fairly lean, even on "pre-emissions control" engines. Additionally, a richer idle mixture will also use more fuel when you're idling (no different at all any other time).

For the record, nothing you can do to your idle mixture will result in engine damage. A lean mixture at high load (open throttle) will result in high temperatures and potentially also detonation, both of which cause problems. At idle the engine simply isn't burning enough fuel to get anything hot enough to cause a problem. Feel free to twiddle away and see what setting you prefer...
__________________
brighton2expeditions
'02 Africa Twin (sold), GSX-R 1000 K5 (sold), '97 TL1000S, '08 DRZ400 SM/S, '92 CRM250
Reply With Quote
  #3  
Old 15 May 2011
The Raven's Avatar
Gold Member
Veteran HUBBer
  
Join Date: Jul 2009
Location: liberty, Maine
Posts: 148
The setting indicated in the manual is the initial setting. If you delve further you will find that different models have different settings.

The proper way to address this is to lean the screws out until the engine reaches it's highest rpm...then richen it up a tad. Every bike and carb is different.
__________________
I'm Raven, a forever banished exile from ADV,

Check out our blog at
www.nomapnomads.com
Reply With Quote
  #4  
Old 19 May 2011
Registered Users
Veteran HUBBer
  
Join Date: Feb 2002
Location: Coimbra, Portugal
Posts: 277
I was running with ¾ turn but last time I adjusted the carbs I set the mixture a bit richer.

Now I have 3 strange symptoms:

-sometimes at tick over one cylinder misses the ignition
-When reaching a red light the after some cruising kms the engine switches off (the tick over is higher than it was)
-at cruising speed sometime the engine momentarily losses power…

Before going back to the old settings am I missing something?
__________________
bernardo feio (Portugal)
2.5 Land Rover Lightweight / BMW R100 GS
Reply With Quote
  #5  
Old 20 May 2011
The Raven's Avatar
Gold Member
Veteran HUBBer
  
Join Date: Jul 2009
Location: liberty, Maine
Posts: 148
My bet is electrical...are you still running the grey OE coil?


Quote:
Originally Posted by bernardo feio lightweight View Post
I was running with ¾ turn but last time I adjusted the carbs I set the mixture a bit richer.

Now I have 3 strange symptoms:

-sometimes at tick over one cylinder misses the ignition
-When reaching a red light the after some cruising kms the engine switches off (the tick over is higher than it was)
-at cruising speed sometime the engine momentarily losses power…

Before going back to the old settings am I missing something?
__________________
I'm Raven, a forever banished exile from ADV,

Check out our blog at
www.nomapnomads.com
Reply With Quote
Reply

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 Registered Users and/or Members and 1 guests)
 
Thread Tools
Display Modes
Linear Mode Linear Mode

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
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Security anti-theft screws bacardi23 Yamaha Tech 2 18 Jul 2010 14:49
Nuvo turns on after bike is turned off planethopper Navigation - Maps, Compass, GPS 6 1 Jun 2010 10:56
Various genuine ktm screws for sale Giles4060 KTM Tech 3 9 May 2006 18:07
carb pilot air screw - how many turns zebra Yamaha Tech 7 18 May 2005 00:46
nuts and a few loose screws dw Equipping the Bike - what's the best gear? 8 8 Jan 2001 03:24


All times are GMT +1. The time now is 12:25.

Contact Us - Horizons Unlimited Motorcycle Travellers Website - Archive - Privacy Statement - Top