Go Back   Horizons Unlimited - The HUBB > Technical, Bike forums > Yamaha Tech
1990 XT600 Engine, 1986 Carb 1990 XT600 Engine, 1986 Carb
Register FAQ Calendar Search Today's Posts Mark Forums Read
Yamaha Tech Originally the Yamaha XT600 Tech Forum, due to demand it now includes all Yamaha's technical / mechanical / repair / preparation questions.
Photo by Ellen Delis, Lagunas Ojos del Campo, Antofalla, Catamarca

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


Photo by Ellen Delis,
Lagunas Ojos del Campo,
Antofalla, Catamarca



Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 21 Sep 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
1990 XT600 Engine, 1986 Carb
As the title says! Engine has 22K miles, the carb has 7K miles. The engine starts and runs, but has some minor, quietish backfiring throughout the rev range. I can feel puffs of air from the air intake when it backfires. I also feel it is running a little lean. Valves adjusted, Carb cleaned. PO removed the baffle from the exhaust.

What do you suggest I look at to possibly richen the mixture and secondly to eliminate the back firing throughout the rev range?

T
Reply With Quote
  #2  
Old 21 Sep 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Oh, sorry. Yes, I replaced them with new boots. Also the air joints (rubber boots on the intake side) are new. They seem to have a good seal although I am using common hose clamps around each union.
Reply With Quote
  #3  
Old 24 Sep 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Boots are too big.
Here's the issue as suggested by Sheva Deva on another site and confirmed just now. I have a 1986 carb on a 1990 airbox and intake manifold; the problem is the intake on the 86 carb is significantly smaller than the 1990 airbox joint.

So now I have to figure out how to make the intake manifold and airbox joints smaller, or make the carb intake larger. I'm thinking of gaffer tape, or cutting the boots to allow cinching down. I will also research the 1986 airbox joints to see if they will fit the 1990 airbox.

Any other ideas? It seems clear that this will solve my rough idle problem.
Reply With Quote
  #4  
Old 25 Sep 2014
xtrock's Avatar
Registered Users
Veteran HUBBer
  
Join Date: May 2013
Location: Norway
Posts: 1,325
find a rubber hose to fill the gap, cars have alot of different dim to choose from.
Reply With Quote
  #5  
Old 25 Sep 2014
Registered Users
Veteran HUBBer
  
Join Date: Mar 2013
Location: cajah's Mountain N.C.
Posts: 124
The secondary carb to cylinder manifold is bigger on the 86 than on the 90. I used two primary carb manifolds or you could use the 86 manifolds. THUMPTHUMP
Reply With Quote
  #6  
Old 25 Sep 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Thank you for the suggestions! I found a perfect rubber coupling at the hardware store, trimmed it down and it fit inside the airbox joint perfectly. It's a very tight fit on the 86 carb so i think it'll work. Fingers crossed.
Reply With Quote
  #7  
Old 25 Sep 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Rubber boot from the hardware store
It fits inside the airbox joint and outside the 86 carb intake.
Attached Thumbnails
1990 XT600 Engine, 1986 Carb-kimg0935.jpg  

1990 XT600 Engine, 1986 Carb-kimg0936.jpg  

Reply With Quote
  #8  
Old 25 Sep 2014
Registered Users
Veteran HUBBer
  
Join Date: May 2013
Location: Wisconsin, USA
Posts: 827
That won't cause any backfiring to the engine unless it isn't the regular form it is normally called . That loose manifold will just allow dirt into the carb. Did you check the coasting enricher diaphragm on the side of the carb?
Reply With Quote
  #9  
Old 4 Oct 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Coasting Enricher
jjrider

The diaphragm looks perfect and fits well. I ordered a repair kit anyway that includes a new one. What should I be looking for in the coasting enricher assembly?
Reply With Quote
  #10  
Old 6 Oct 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Update
I'll post an update for the sake of those using the search feature of HUBB. Yesterday I removed the carb again (third time) and did another thorough cleaning. (I don't have the coasting enricher kit yet). The engine ran as it did before but I decided to drive it a bit and see what happened. I rode for about an hour off road and on, at varying speeds and rpm. The engine got smoother and smoother. It's not perfect yet, but it's very close. I wonder if the problem was some junk or carbon buildup on the valves that worked itself out with use. Or maybe it just needed some lovin'. Will try again today, and install the coasting enricher kit when it comes. But it's running better than it was. Oh, I also dumped a can of Seafoam in the tank before riding it for the hour yesterday.
Reply With Quote
  #11  
Old 7 Oct 2014
Registered Users
Veteran HUBBer
  
Join Date: May 2013
Location: Wisconsin, USA
Posts: 827
Could very well have been some gunk that is slowly dissolving with the Sea Foam and/or gas. The coasting enricher just has that diaphram that should be nice and flexable with no holes, plus a spring and plunger that should move freely. The passageway should get a good blast of air to make sure it comes out the other end. Not a whole lot to it but can really cause a lot of backfiring when a person lets off the gas.
Reply With Quote
  #12  
Old 27 Oct 2014
Registered Users
New on the HUBB
  
Join Date: Jul 2014
Location: Hawaii
Posts: 13
Update
Another update for those doing a search on rough running: I noticed at some point that the installation I had made of the carb was not good. The carb was slightly canted to the side at an angle relative to the face of the engine. When I loosened the boots and muscled the carb around straight, the last of the rough running issues were resolved. This is something that could easily be overlooked in a forum response because we would assume that the mechanic had installed everything straight and square. I'm here to tell you to double check!

Went for a long ride this afternoon down the coast and the Zombie Apocalypse Response Bike is performing flawlessly. Now for some off-roading.

d
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
XT600 Parts Manuals (1990 - 2002) kentfallen Yamaha Tech 5 29 Jul 2016 11:13
XT600 Engine Rebuild Phoenix6 Yamaha Tech 15 2 Feb 2015 22:02
XT600 engine rattle etsihel Yamaha Tech 23 6 Oct 2014 14:48
1990 XT600 Rough Running Tioli Yamaha Tech 6 14 Aug 2014 01:00
XT600E 2002 Engine Oil Trichelia Yamaha Tech 17 17 Nov 2011 14:25

 
 

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

HU Event and other updates on the HUBB Forum "Traveller's Advisories" thread.
ALL Dates subject to change.

2024:

Add yourself to the Updates List for each event!

Questions about an event? Ask here

HUBBUK: info

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...

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 16:52.

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