Go Back   Horizons Unlimited - The HUBB > Technical, Bike forums > KTM Tech
KTM 640 Engine Cuts on Braking & Hills KTM 640 Engine Cuts on Braking & Hills
Register FAQ Calendar Today's Posts
KTM Tech KTM Tech Forum - For Questions specific and of interest to KTM riders only.
Photo by Andy Miller, UK, Taking a rest, Jokulsarlon, Iceland

I haven't been everywhere...
but it's on my list!


Photo by Andy Miller, UK,
Taking a rest,
Jokulsarlon, Iceland



Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 30 Aug 2010
Registered Users
HUBB regular
  
Join Date: Feb 2009
Location: Sydney, Australia
Posts: 80
KTM 640 Engine Cuts on Braking & Hills
Hi,

My 2006 KTM 640 Adventure engine has a problem. It starts and runs ok, however on heavy braking with high RPM it backfires like a shotgun. When I brake hard with idle RPM the engine cuts. The engine will also cut on idle when going down hills. Rather annoying when riding hard in traffic.

I've tried troubleshooting various things - fuel pump, choke cable, float height. etc. But can't figure it out. One thing I did notice when playing with the needle height is that the membrane slide in the carb seems to have a bit of forwards and backwards play in it causing wear on the needle - It will need replacing when I can afford it.


Does anyone have any suggestions?
__________________
http://ktmthump.blogspot.com
Reply With Quote
  #2  
Old 30 Aug 2010
Registered Users
Veteran HUBBer
  
Join Date: Mar 2008
Location: Rotoiti, New Zealand
Posts: 138
Maybe an electrical problem not a carb one? The weight shift braking & downhill might be nudging something? I'd check the wiring under the tank for any rubbing. Maybe try bypassing the stand switch too.

BST carbs are bad for wearing out, apparently moto-lab.com is the best place to get a rebuild kit. However when I rebuilt mine at about 80K km it was well worn & generally running a bit crappy, but no cutting out like you describe.

Cheers
Clint
Reply With Quote
  #3  
Old 4 Sep 2010
Registered Users
HUBB regular
  
Join Date: Feb 2009
Location: Sydney, Australia
Posts: 80
Thanks for the advice regarding rebuild - once I get some money together I will probably start a rebuild job beginning with the carb.

I've not had a detailed look at the electrical connections but will keep my eye open for anything next time I have the tank off. To me, something screams bottom end mixture problem. I have discovered that the mixture screw is completely jammed solid so have had to lean the needle valve all the way out. The needle also seems to wear pretty quickly too.

My bike doesn't have a sidestand switch so I can cross that one off my list of potential gremlins.

Cheers

Duncan
__________________
http://ktmthump.blogspot.com
Reply With Quote
  #4  
Old 23 Aug 2011
Registered Users
Veteran HUBBer
  
Join Date: Sep 2002
Location: london,england
Posts: 191
i had a lc4 400 that did the same thing, especially when doing stoppies. unfortunately i never found the fault. sorry.
Reply With Quote
  #5  
Old 23 Aug 2011
Registered Users
HUBB regular
  
Join Date: Dec 2006
Location: York
Posts: 20
1. What was reported in the original post, sounds as if there has been some adjustments from standard. Namely carb settings. I would put these back to standard (all standard carb setting in KTM manual, with specs). Standard setting before trying moving away from those and then only one setting made to try. You will always have a known situation to go back to.

2. Try raising the tickover speed, 1400 to 1500 rpm is about right.

3. Mine used to stall/cut out sometimes for no apparent reason if the air filter is dirty/blocked, clean out airbox properly with blue roll/tissue and maintence spray and fit a new/oiled filter.
4. If you think its electrical - The underseat fuse box towards the back of the bike above the battery. The fuses have a habit of loosening off and being slightly baggy in the holders. You can push up tighter the fuse holder grips for the blades with a very small screwdriver or scriber. This makes them grip the fuses tighter. Could be that cutting out the ignition circuit with vibration, but you did'nt mention electrics cutting out at all in the original post.
Attached Thumbnails
KTM 640 Engine Cuts on Braking & Hills-640-carb-settings.jpg  

Reply With Quote
  #6  
Old 14 Sep 2011
Registered Users
New on the HUBB
  
Join Date: Mar 2008
Location: Arkansas
Posts: 14
Sounds like you need to check the float level in the carb.
There is a similar issue thread on advrider about LC4 bogging after jumps.
Reply With Quote
Reply

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 Registered Users and/or Members and 1 guests)
 

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
HELP- XT600 cuts out at 65MPH rdelta Yamaha Tech 41 9 Sep 2020 23:41
Engine cuts out over 50 mph pt5eng2 Yamaha Tech 18 15 Jan 2016 19:14
Anyone been to Tsodilo Hills, Aha Hills and Gcwihaba Caves? Roboyobo sub-Saharan Africa 3 4 Aug 2010 18:21
Engine braking & gear ratios TommyT Kawasaki Tech 2 12 Dec 2009 17:10
braking up lost1 KTM Tech 0 18 Jul 2003 05:22

 
 

Announcements

Thinking about traveling? Not sure about the whole thing? Watch the HU Achievable Dream Video Trailers and then get ALL the information you need to get inspired and learn how to travel anywhere in the world!

Have YOU ever wondered who has ridden around the world? We did too - and now here's the list of Circumnavigators!
Check it out now, and add your information if we didn't find you.

Next HU Eventscalendar

ALL Dates subject to change.

2025 Confirmed Events:

  • Virginia: April 24-27 2025
  • Queensland is back! May 2-4 2025
  • Germany Summer: May 29-June 1 2025
  • CanWest: July 10-13 2025
  • Switzerland: Date TBC
  • Ecuador: Date TBC
  • Romania: Date TBC
  • Austria: Sept. 11-14
  • California: September 18-21
  • France: September 19-21 2025
  • Germany Autumn: Oct 30-Nov 2 2025

Add yourself to the Updates List for each event!

Questions about an event? Ask here

See all event details

 
World's most listened to Adventure Motorbike Show!
Check the RAW segments; Grant, your HU host is on every month!
Episodes below to listen to while you, err, pretend to do something or other...

Adventurous Bikers – We've got all your Hygiene & Protection needs SORTED! Powdered Hair & Body Wash, Moisturising Cream Insect Repellent, and Moisturising Cream Sunscreen SPF50. ESSENTIAL | CONVENIENT | FUNCTIONAL.

2020 Edition of Chris Scott's Adventure Motorcycling Handbook.

2020 Edition of Chris Scott's Adventure Motorcycling Handbook.

"Ultimate global guide for red-blooded bikers planning overseas exploration. Covers choice & preparation of best bike, shipping overseas, baggage design, riding techniques, travel health, visas, documentation, safety and useful addresses." Recommended. (Grant)



Ripcord Rescue Travel Insurance.

Ripcord Rescue Travel Insurance™ combines into a single integrated program the best evacuation and rescue with the premier travel insurance coverages designed for adventurers.

Led by special operations veterans, Stanford Medicine affiliated physicians, paramedics and other travel experts, Ripcord is perfect for adventure seekers, climbers, skiers, sports enthusiasts, hunters, international travelers, humanitarian efforts, expeditions and more.

Ripcord travel protection is now available for ALL nationalities, and travel is covered on motorcycles of all sizes!


 

What others say about HU...

"This site is the BIBLE for international bike travelers." Greg, Australia

"Thank you! The web site, The travels, The insight, The inspiration, Everything, just thanks." Colin, UK

"My friend and I are planning a trip from Singapore to England... We found (the HU) site invaluable as an aid to planning and have based a lot of our purchases (bikes, riding gear, etc.) on what we have learned from this site." Phil, Australia

"I for one always had an adventurous spirit, but you and Susan lit the fire for my trip and I'll be forever grateful for what you two do to inspire others to just do it." Brent, USA

"Your website is a mecca of valuable information and the (video) series is informative, entertaining, and inspiring!" Jennifer, Canada

"Your worldwide organisation and events are the Go To places to for all serious touring and aspiring touring bikers." Trevor, South Africa

"This is the answer to all my questions." Haydn, Australia

"Keep going the excellent work you are doing for Horizons Unlimited - I love it!" Thomas, Germany

Lots more comments here!



Five books by Graham Field!

Diaries of a compulsive traveller
by Graham Field
Book, eBook, Audiobook

"A compelling, honest, inspiring and entertaining writing style with a built-in feel-good factor" Get them NOW from the authors' website and Amazon.com, Amazon.ca, Amazon.co.uk.



Back Road Map Books and Backroad GPS Maps for all of Canada - a must have!

Your ad could be here, on EVERY page of the HUBB, or the whole website, or as many as you like!

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 R80G/S.

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 all over the world with the help of volunteers; 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, or ask questions on the HUBB. 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.



All times are GMT +1. The time now is 10:39.

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