Go Back   Horizons Unlimited - The HUBB > Technical, Bike forums > Yamaha Tech
misfire misfire
Register FAQ Calendar Today's Posts
Yamaha Tech Originally the Yamaha XT600 Tech Forum, due to demand it now includes all Yamaha's technical / mechanical / repair / preparation questions.
Photo by Ulrike Hahnel, Rock Formations on the Lagune Route, Bolivia

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


Photo by Ulrike Hahnel,
Rock Formations on the
Lagune Route, Bolivia



Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 10 May 2004
Registered Users
HUBB regular
  
Join Date: Apr 2004
Location: bristol uk
Posts: 67
misfire
Hi all

Following a rebore, and a new BSM exhaust, which works on standard jetting, I am getting the occasional misfire when the throttle is open approx 3/4. Do I need to adjust the mix, and if so, do I adjust the pilot screw on the bottom of the carb?
The spark plug colour looks OK. I have also just started using unleaded petrol, rather than LRP, but I am using Pro Boost, on the advice of the person who rebored the barrel.
The misfire was there when using LRP however, so I don't think this is relevant.
Any advice would be appreciated.
Cheers Dave
Reply With Quote
  #2  
Old 10 May 2004
Registered Users
Veteran HUBBer
  
Join Date: Aug 2002
Location: Hendrik Ido Ambacht, Holland
Posts: 360
Can be anything according to the symptom, but the idle mixture screw is only for the idle mixture. Check air filter first. Also please specify what exactly you mean when you say 'misfire'. Sounds like the spark plug skips once!?

------------------
Fred, XTZ660, Holland.
__________________
Fred, XTZ660, Holland.
Reply With Quote
  #3  
Old 11 May 2004
Registered Users
HUBB regular
  
Join Date: Apr 2004
Location: bristol uk
Posts: 67
Hi Fred
The filter seems OK, and I've changed the plug and cap. Also the CDI unit is only about 1 1/2 years old. I,m pretty sure the coil is OK.
It feels like it is missing a beat, and happens between 3 1/2 to 4000 revs. I guess it feels as if it might be choking a bit. It may be a blockage in a jet I suppose.

Dave
Reply With Quote
  #4  
Old 11 May 2004
Steve Pickford's Avatar
Contributing Member
Veteran HUBBer
  
Join Date: Jul 2003
Location: Oxford, UK
Posts: 994
Leave the pilot mixture screw alone, it is only relevant from closed to 1/4 throttle max.

Does the misfire occur at a steady throttle or when you're accelerating as well?

Steve
__________________
My photos: www.possu.smugmug.com
Reply With Quote
  #5  
Old 12 May 2004
Registered Users
HUBB regular
  
Join Date: Apr 2004
Location: bristol uk
Posts: 67
Hi Steve

It has been occuring at both. However, today I put a cooler running spark plug in it, and also thoroughly cleaned the air filter and that seems (touch wood) to have solved the problem.
I think maybe it had been running a bit hot after the top end rebuild. I'm still running it in.

Dave
Reply With Quote
  #6  
Old 12 May 2004
Registered Users
Veteran HUBBer
  
Join Date: Aug 2002
Location: Hendrik Ido Ambacht, Holland
Posts: 360
So it's not a 'misfire' as in 'ignition not firing' [you wouldn't notice it missing a beat] but more like a mixture problem. Can be both too lean or too rich. Try to listen to the sound from the exhaust. If it sounds like blurry it's probably too rich, and if there's no sound but no reaction to the throttle it's probably too rich. But it is best to go to a test bench and have it analyzed. As we say here : meten is weten! [to measure is to be sure]

------------------
Fred, XTZ660, Holland.
__________________
Fred, XTZ660, Holland.
Reply With Quote
  #7  
Old 14 May 2004
Registered Users
HUBB regular
  
Join Date: Apr 2004
Location: bristol uk
Posts: 67
Hi

Thanks for all your help. Its now running smoothly with an 8 plug back in, so it was the filter. It looked clean, and had only been serviced (allegedly) abou 400 miles ago, but when I washed it out, it was filthy.

Cheers Dave
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

 
 

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.

2024:

  • California: April 18-21
  • Virginia: April 25-28
  • Germany Summer: May 9-12
  • Québec: May 17-19
  • Bulgaria Mini: July 5-7
  • CanWest: July 11-14
  • Switzerland: August 15-18
  • Ecuador: August 23-25
  • Romania: August 30-Sept 1
  • Austria: September 12-15
  • France: September 20-22
  • Germany Autumn: Oct 31-Nov 3

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. 11-15
  • 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 01:14.

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