Go Back   Horizons Unlimited - The HUBB > Technical, Bike forums > Honda Tech

Honda Tech Honda Tech Forum - For Questions specific and of interest to Honda riders only. Questions comparing which bike is best etc go in the "Which Bike" forum.
Contact Overland Solutions for all your custom modifications and setup for overland travel.

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 4 Nov 2010
Registered Users
New on the HUBB
 
Join Date: Jan 2010
Location: bristol uk
Posts: 11
Question Africa twin altitude problem, any advice appreciated!

Hi. I'm curently in Albania exploring the mountain tracks on my africa twin. (it is bloody amaze g by the way )
I am having problems loosing power and running very hot once I get to high altitude of only 1500ft. I've done lots of resirch on blogs and most people manage 2500ft befor they have any power loss.
I will be in Greece soon so I'm sur there will be mechanics and workshops I can use if necessary to sort the problem..
Has anyone got any advice as to what to do, or why my bike is so sensitive?
I have an after Market exaust (Remus) but they recon this should not affect the running.. But they also said they'd never tested it at altitude.
I could remove the airfilter but am doing lots of dusty off roading and have a log long way to go.
Perhaps changing the jets? Any suggestions on what jets??
I saw a post about modifications for africa twins at 4000ft- but may be a bit extream for me and perhaps after these mods it will struggle at sea level?
Anyways, any advice is very. Much appreciated
Reply With Quote
  #2  
Old 4 Nov 2010
AliBaba's Avatar
Registered Users
Veteran HUBBer
 
Join Date: Apr 2001
Location: Norway
Posts: 1,350
I've no experience with the AT so this is generally for carbed bikes.
As a rough rule of thumb you loose 10% power every 1000m (3000ft) with a healthy engine This means that you should loose approx 5% at 1500 ft, and that's "nothing".

The reason why you loose power is that your air/fuel-mixture gets fatter (less air for the same amount of petrol). As you mention it's possible to remove the airfilter to get more air, but it's usually not smart in the long run.
Another option is to remove the snorkels on the dirty side of the airfilter (if AT have snorkels), or modify the dirty side (drill holes etc).
The other option is to reduce the amount of petrol. You can do this by smaller main-jets and/or drop the needle.

Remember that running fat is not dangerous for the engine, but running lean can be very dangerous. So if you do a modification you have to restore it to original state before you get to a lower elevation.
If you have enough power there is nothing wrong to keep on driving like it is now.


The Remus itself usually make the bike run leaner (which should help you) but it's possible that jets/needleposition where changed at the same time to compensate for this. Maybe it's overcompensated. If the carbs are worn they also make the engine rune rich. Do you have a dyno-kit? They suck.... A dirty airfilter will also make the engine run fatter.

I would have done a testride (a few 100 meters) without the airfilter to see if it gets better.
Reply With Quote
  #3  
Old 5 Nov 2010
Registered Users
New on the HUBB
 
Join Date: Jan 2010
Location: bristol uk
Posts: 11
Hi there, don't know your name but big thanks for your reply, very helpful info. The bike is quite jucy at see level- more than the stated mpg in the manual- could this also be a sign that it's running with too much fuel and not enough air on ground level??
Cheers pip
Reply With Quote
  #4  
Old 5 Nov 2010
Registered Users
New on the HUBB
 
Join Date: Jan 2010
Location: bristol uk
Posts: 11
Oh yeah- If I changed the needle to run leaner (assuming the last chap had changed it to run fatter when he fitted the Remus) how could I then tell if it was running too lean at sea level? I obviously don't wan to damage the bike and it's alot of work to get to the carbs each time I go up and down.
Thanks again- pip
Reply With Quote
  #5  
Old 5 Nov 2010
AliBaba's Avatar
Registered Users
Veteran HUBBer
 
Join Date: Apr 2001
Location: Norway
Posts: 1,350
It's not easy to see if the bike runs lean. One way is to read the plugs but with todays petrol this is pretty difficult. It's possible to install an AF-meter on the bike, but that's maybe a bit extreme...


There is no way to make a carbed bike run perfect at all elevations but a good start is that it runs right at sea-level. Best way to do this (especially on a bike with modified exhaust) is to overhaul the carbs and then take a dyno-run where you adjust to get the right air/fuel-ratio. This might involve changing jets.
If the air/fuel-ratio is correct at sea-level you can usually go up to at least 3000 metrers (10.000 ft) without problems, but you will loose power and your idle will decrease.
Reply With Quote
  #6  
Old 5 Nov 2010
Registered Users
Veteran HUBBer
 
Join Date: Oct 2003
Location: Cracow, Poland
Posts: 157
I was on my AT over 5000 meters, without any modifocations. But I had such a problem you described. Check if your your choke works properly. Probably you have bad assembled choke cable. Check ecpecially if it is correctly assembled with carburetor.
If your bike consume more than usually you can expect it is problem with choke...
__________________
www.africatwin.com.pl
Reply With Quote
  #7  
Old 10 Nov 2010
Gold Member
Veteran HUBBer
 
Join Date: Jan 2002
Location: Toronto, Canada
Posts: 917
Pip:

I wonder if perhaps your power loss has nothing whatsoever to do with altitude, but instead is caused by carburator icing?

Normally, a change of elevation from sea level to 1,500 feet should result in no detectable difference for a carburetted engine. Heck, if it did make a difference, no-one would be able to drive in Switzerland (or, for that matter, across North America).

At this time of year, outside air temperatures are rather low (perhaps 10 to 15 degrees C) and the air can be quite moist. When cool air is drawn into the venturi of the carburetor, the temperature drops, and ice can form in the carburetor throat. I had this happen to me on several occasions on a VW Beetle. The result is a slow but steady loss of power, and eventually, the engine just sputters out. It might just be coincidental that you are travelling uphill (rising in elevation) as this is happening.

Next time you encounter your 'power loss', see if things return to normal after the engine has been turned off for about 60 to 90 minutes (sufficient time for the residual heat in the engine to melt any ice that may have built up in the carb). In particular, if you have the chance, park the bike in a heated enclosure for a few hours, then start it up and see how it runs. If the problem disappears after either of these two actions, then your problem is carburator ice and not mixture.

This Wikipedia article explains the phenomenon: Carburetor Icing, and this aviation-specific article provides considerably more detail: Carburetor Icing: Part II, Symptoms and Remedies

Note the reference to "temperatures between +5C and +15°C" in the aviation article.


Michael
Reply With Quote
  #8  
Old 5 Dec 2010
dstehouwer's Avatar
Gold Member
Veteran HUBBer
 
Join Date: Jun 2008
Location: Now Alberta, Canada! (originally the Netherlands)
Posts: 257
Maybe not helping you, but does give some information:

We have been driving our Africa Twins offroad this summer in The Alps, up to 3006 meters (9 862.20472 feet according Google ) and they were running fine. So I think something else is wrong, not so much the altitude...

to add to tat, we were driving through the snow sometimes up there.... so also quite cold!
Reply With Quote
  #9  
Old 7 Dec 2010
Registered Users
HUBB regular
 
Join Date: Mar 2006
Location: N.Yorks UK
Posts: 79
An oldish post I know, 1500ft is not 'high altitude' - even if you meant 1500mtr, the bike should cope fine.

Are the chokes stuck causing overly rich running?

Phil
__________________
650 Transalp
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 Registered Users and/or 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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Battery problem with Africa twin ATWR Honda Tech 6 30 Jul 2010 15:51
Africa Twin Chain Problem In Syria!!!! Tybalt Tech 15 30 Jan 2009 20:46
Another Africa Twin problem (ignition I think) Tybalt Tech 10 20 Dec 2008 22:43
6 month trip advice appreciated Steveandphilstrip Route Planning 3 3 Dec 2008 07:57
Africa Twin at altitude Del Boy Honda Tech 19 2 Oct 2007 14:19

 
 


HU DVD Summer Special!

Now that summer is here, get On the Road! Take 30% off the Achievable Dream - On the Road! 2-DVD set until August 31 only. Get On the Road! Learn the tips to staying healthy, happy and secure on your motorcycle adventure!

Our veteran travellers share their tips (and great stories) for staying healthy, happy and secure on your motorcycle adventure.

"A fantastic, informative and inspirational DVD."

"It's brilliant - thank you very much!"

Check it out at the HU Store! Remember to use Coupon Code 'ONTHEROAD' on your order when you checkout.


Renedian Adventures


Renedian Adventures

What others say about HU...

"I just wanted to say thanks for doing this and sharing so much with the rest of us." Dave, USA

"Your website is a mecca of valuable information and the DVD series is informative, entertaining, and inspiring! The new look of the website is very impressive, updated and catchy. Thank you so very much!" Jennifer, Canada

"...Great site. Keep up the good work." Murray and Carmen, Australia

"We just finished a 7 month 22,000+ mile scouting trip from Alaska to the bottom of Chile and I can't tell you how many times we referred to your site for help. From how to adjust your valves, to where to stay in the back country of Peru. Horizons Unlimited was a key player in our success. Motorcycle enthusiasts from around the world are in debt to your services." Alaska Riders

contest pic

10th Annual HU Travellers Photo Contest is on now! This is an opportunity for YOU to show us your best photos and win prizes!

NEW! HU 2014 Adventure Travel T-shirts! are now available in several colors! Be the first kid on your block to have them! New lower prices on synths!

HU 2014 T-shirts now in!

Check out the new Gildan Performance cotton-feel t-shirt - 100% poly, feels like soft cotton!


What turns you on to motorcycle travel?


Global Rescue, WORLDwide evacuation services for EVERYONE

Global Rescue is the premier provider of medical, security and evacuation services worldwide and is the only company that will come to you, wherever you are, and evacuate you to your home hospital of choice. Additionally, Global Rescue places no restrictions on country of citizenship - all nationalities are eligible to sign-up!


New to Horizons Unlimited?

New to motorcycle travelling? New to the HU site? Confused? Too many options? It's really very simple - just 4 easy steps!

Horizons Unlimited was founded in 1997 by Grant and Susan Johnson following their journey around the world on a BMW R80 G/S motorcycle.

Susan and Grant Johnson Read more about Grant & Susan's story

Membership - help keep us going!

Horizons Unlimited is not a big multi-national company, just two people who love motorcycle travel and have grown what started as a hobby in 1997 into a full time job (usually 8-10 hours per day and 7 days a week) and a labour of love. To keep it going and a roof over our heads, we run events (22 this year!); we sell inspirational and informative DVDs; we have a few selected advertisers; and we make a small amount from memberships.

You don't have to be a Member to come to an HU meeting, access the website, the HUBB or to receive the e-zine. What you get for your membership contribution is our sincere gratitude, good karma and knowing that you're helping to keep the motorcycle travel dream alive. Contributing Members and Gold Members do get additional features on the HUBB. Here's a list of all the Member benefits on the HUBB.


Books & DVDs

amazon

All the best travel books and videos listed and often reviewed on HU's famous Books page. Check it out and get great travel books from all over the world.


Motorcycle Express for shipping and insurance!

Motorcycle Express

MC Air Shipping, (uncrated) USA / Canada / Europe and other areas. Be sure to say "Horizons Unlimited" to get your $25 discount on Shipping!
Insurance - see: For foreigners traveling in US and Canada and for Americans and Canadians traveling in other countries, then mail it to MC Express and get your HU $15 discount!




All times are GMT +1. The time now is 07:53.