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

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.
Contact Overland Solutions for all your custom modifications and setup for overland travel.

7 Litre Camel Tank Lets You Explore More, Click to Find out More!

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 8 Sep 2005
Registered Users
Veteran HUBBer
 
Join Date: Jun 2005
Location: Cape Town / South Africa
Posts: 223
Surging R80GS

HELP ! ! !
Maybe someone have had this problem before and can help with good information.
I have a broplem with terrable surging on a GS. The carbs have been rebuilt, meaning repacing of all rubber parts, floats, needles etc.
The problem only starts to hapen when you accelerate past 4000rpm in any gear. Below 4000rpm the bike pull very well with loads of power and is in fact very light on feul, but when you hit 4000rpm it just stop accelerating and surges voilently. When you have a bit of down hill and can push the revs up to 5000rpm it will start running smooth again.
Sofar I have replaced the needle nozzle with a 2.64 versus the 2.68 that was in there and have dropped the main needles with one notch to the 2nd possition.
The main jet is 135 and I am going to install a 145 but the main jet should influence the rev range for the last 1000 or so rpm to full throttle.

[This message has been edited by gsworkshop (edited 08 September 2005).]
Reply With Quote
  #2  
Old 9 Sep 2005
Contributing Member
Veteran HUBBer
 
Join Date: Nov 2000
Location: Wirral,UK
Posts: 170
Hi

I had a 'similar' problem once after fitting a K&N air filter in place of a standard one to an R80GS with Y-piece (no re-jetting required apparently). Bike went fine below 3500rpm but nuts after - then ran perfect with the OE filter back in. You could well be on the right track with the air intake side of things.
__________________
Sean
Reply With Quote
  #3  
Old 9 Sep 2005
simmo's Avatar
Contributing Member
Veteran HUBBer
 
Join Date: Nov 2002
Location: melbourne
Posts: 557
Your tank bag straps arn't being sucked into the airbox snorkles are they....dont ask how I could even suggest such a thing.
__________________
Close to Antarctica and a long way from reality
Reply With Quote
  #4  
Old 11 Sep 2005
Registered Users
HUBB regular
 
Join Date: Oct 2003
Location: Norway
Posts: 70
Hi, do you use any fuelfilter?? If so, maybe thet gives too much resistance, and it dosent get enough fuel??
Just a sugestion.. Hav e just fitted K&N on my 91mod R80GS with no problems.

-yngve-
Down under
www.gravelseekers.com
Reply With Quote
  #5  
Old 12 Sep 2005
Contributing Member
Veteran HUBBer
 
Join Date: Jul 2002
Location: Sydney, NSW, Australia
Posts: 1,366
Is the fuel tank vented correctly? If the vent is blocked then fuel will not flow out of the tank quickly. Open the fuel filler and see if the problem goes away (leave the cap on, but loose ... and don't do it with a full tank of fuel).
__________________
---
Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S
Reply With Quote
  #6  
Old 13 Sep 2005
Registered Users
Veteran HUBBer
 
Join Date: Jun 2005
Location: Cape Town / South Africa
Posts: 223
Thanks for the reply, these are all valed pionts.
The problem was first a needle nozzle to large at 2.68 and then I replaced them with old 2.64's which were worn. After replacing them with new 2.64's sudenly she was going like a rocket.
If you feel you loose a bit of power around 110km/h this should be the first thing to check after cheking the other more obviouse things you guys refered to in this forum.
Needle nozzles tend to wear causing an over rich mixture the moment the taper on the main needle start to emerge from the needle nozzle or needle jet.
This will hapen at almost exacly 4000rpm or 110km/h if in 5th gear.
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


 
 


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 03:38.