ADVrider

Go Back   ADVrider > Riding > Regional forums > The Rockies It's all downhill from here...
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-10-2012, 05:50 AM   #1
Ricardito OP
Gnarly Adventurer
 
Joined: Apr 2011
Oddometer: 101
CB700SC carb cleaning

Gents,
I just brought home a very very nice 1984 Honda Nighthawk, CB700SC, bought from the original owner with only 6,030 miles. It's not been ridden much for the past few years and as a result it will hardly run unless partially on choke. Carbs need cleaning and, though I suppose I could do it, I'd rather have a pro who does it frequently tackle the job. Who can you recommmed that is experienced, reliable and trustworthy in the Boulder/Longmont area? I'd rather do it myself than have the bike disappear into the backroom of some dealership for several days. If you can personally vouch for a good tech, please let me know.
thx
Ricardito is offline   Reply With Quote
Old 04-10-2012, 06:55 AM   #2
MrBob
Geezers Rule
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,527
Great bike Ric. I had one and loved it. There is a guy who lives in Longmont and advertises on CL, something about Professional Carb work.
http://fortcollins.craigslist.org/mcd/2943605734.html
I don't know anything about him but you could check for any reviews on Yelp. Otherwise, Epic Motorsports. They did a good job on my XT carb. Their new home is next to Earth Roamers on I-25.
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad

MrBob screwed with this post 04-10-2012 at 08:18 AM
MrBob is offline   Reply With Quote
Old 04-10-2012, 03:23 PM   #3
Ricardito OP
Gnarly Adventurer
 
Joined: Apr 2011
Oddometer: 101
Thanks Bob. This is very helpful and gives me some options, but I have a question: What's Yelp and how do I access it?
Ricardito is offline   Reply With Quote
Old 04-10-2012, 03:33 PM   #4
gtackett
Studly Adventurer
 
gtackett's Avatar
 
Joined: Jun 2008
Location: Bedford, IN
Oddometer: 701
I had the same issue with mine a few years back. A mechanic friend suggested turning the air/fuel(?) Screws on the bottom about 1 turn. You have to take off the metal plate which prevents them from turning.

Worked for me.... hope that was enough info.

Sent from my DROID Pro using Tapatalk 2
__________________
2006 KLX250
1985 CB700SC
1990 KX250
gtackett is offline   Reply With Quote
Old 04-10-2012, 03:49 PM   #5
r1200gs_chris
Gnarly Adventurer
 
r1200gs_chris's Avatar
 
Joined: Feb 2011
Location: Brockville
Oddometer: 133
I had a 1984 650 Nighthawk. Great bike but the carbs can be a source of great frustration. There are MANY fuel passages on this bike and cleaning them requires patience. Try running a few tanks of fuel with SEAFOAM added. SEAFOAM and Nighthawks go hand in hand. Next culprit would be a vacuum leak. Check your intake boots and petcock vacuum line for leaks. Light a cigar and let the smoke drift up around the intake boots while the bike is running. A vacuum leak will suck up the smoke. NOTE: MAKE SURE THERE ARE NO FUEL LEAKS BEFORE YOU DO THIS OR YOU WILL HAVE A *FIREHAWK* PM me if you need anymore help.
r1200gs_chris is offline   Reply With Quote
Old 04-10-2012, 03:51 PM   #6
gtackett
Studly Adventurer
 
gtackett's Avatar
 
Joined: Jun 2008
Location: Bedford, IN
Oddometer: 701
2nd the Seafoam. Forgot about using that, too.

Sent from my DROID Pro using Tapatalk 2
__________________
2006 KLX250
1985 CB700SC
1990 KX250
gtackett is offline   Reply With Quote
Old 04-10-2012, 04:41 PM   #7
MeterPig
Meh
 
MeterPig's Avatar
 
Joined: Jul 2007
Location: Parker, Colorado...
Oddometer: 17,089
Why not take them off and soak them? You could do the seafoam thing for a while and never get it to run right.
__________________
You looked down here...didn't you.
MeterPig is offline   Reply With Quote
Old 04-10-2012, 06:20 PM   #8
Blakebird
r-u-n-n-o-f-t
 
Blakebird's Avatar
 
Joined: Feb 2004
Location: Parker, CO
Oddometer: 15,366
If it takes choke to get it to run at low speeds, the low speed circuits in the carb are gummed up.

An intake leak would make the idle climb.

+1 on the Seafoam.

Quote:
Originally Posted by r1200gs_chris View Post
I had a 1984 650 Nighthawk. Great bike but the carbs can be a source of great frustration. There are MANY fuel passages on this bike and cleaning them requires patience. Try running a few tanks of fuel with SEAFOAM added. SEAFOAM and Nighthawks go hand in hand. Next culprit would be a vacuum leak. Check your intake boots and petcock vacuum line for leaks. Light a cigar and let the smoke drift up around the intake boots while the bike is running. A vacuum leak will suck up the smoke. NOTE: MAKE SURE THERE ARE NO FUEL LEAKS BEFORE YOU DO THIS OR YOU WILL HAVE A *FIREHAWK* PM me if you need anymore help.
__________________
IBA #11735 . 1968-present
Blakebird is offline   Reply With Quote
Old 04-10-2012, 06:53 PM   #9
Assfault
Exposed Member
 
Assfault's Avatar
 
Joined: Sep 2007
Location: RockyMountains
Oddometer: 2,052
If you dont want to tackle the job yourself I would recommend Jim @
TFOG Motorsports. http://www.tfogracing.com/
They have been around for quite some time and always put the customers needs first.
My second recommendation would be Mike @ Supertune http://www.supertunemotorsports.com/
__________________
* Assfault, Ass-Fault, Ms Ass, thier neighbors or friends, are not responsible for any incidents, accidents, or accusations, that might result from you using this forum in the pursuit of adventure greatness. Avoid taking ADV before bed time. Do not use if you experince faintness, dizzniess, inversness, difficulty urinating or an erection lasting longer than 4 hours. Thank you*
Assfault is offline   Reply With Quote
Old 04-11-2012, 06:50 AM   #10
Ricardito OP
Gnarly Adventurer
 
Joined: Apr 2011
Oddometer: 101
Thanks to all. I'm reasonably sure it's the low speed jets that are gummed up. The right way to do it would be to soak the carbs, clean the jets and blow the passages with compressed air. Since I'm lazy and not fond of carb cleaner fumes I'll give the SEAFOAM treatment a try for starters and see if that cleans out the passages. If not, I'll have to decide whether to do it myself or have it done by one of the places suggested here.
Ricardito is offline   Reply With Quote
Old 04-11-2012, 07:32 AM   #11
Blakebird
r-u-n-n-o-f-t
 
Blakebird's Avatar
 
Joined: Feb 2004
Location: Parker, CO
Oddometer: 15,366
if you get to the point where you're taking the carbs off to soak....take a look at Hondo's Pine Sol soak (CB900).


http://advrider.com/forums/showthread.php?t=560117
__________________
IBA #11735 . 1968-present
Blakebird is offline   Reply With Quote
Old 04-11-2012, 07:46 AM   #12
r1200gs_chris
Gnarly Adventurer
 
r1200gs_chris's Avatar
 
Joined: Feb 2011
Location: Brockville
Oddometer: 133
If the Seafoam doesn't do the trick take them off an get cleaning. I don't recommend splitting them, keep them all together. After a soak flip them over, remove the floats, and then remove the jets. Get a small wire/guitar string and gently clean out all passages, jet holders, jets, and blow carb cleaner thru every opening. Slap it back together and off you go. Less than an hours work to clean them, not including the soak.
r1200gs_chris is offline   Reply With Quote
Old 04-11-2012, 08:25 AM   #13
MrBob
Geezers Rule
 
MrBob's Avatar
 
Joined: Oct 2005
Location: Boulderish, CO
Oddometer: 7,527
Quote:
Originally Posted by Ricardito View Post
Thanks Bob. This is very helpful and gives me some options, but I have a question: What's Yelp and how do I access it?
http://www.yelp.com/find
You only need to register if you want to post a review.

I've been using this for carb cleaning:
http://www.yamaha-motor.com/outboard...07/detail.aspx
__________________
"When I was younger I was afraid I'd die riding now that I'm old and falling apart, I'm afraid I won't."
bwanacswan's dad
MrBob is offline   Reply With Quote
Old 04-18-2012, 10:37 PM   #14
Cheap Ryder
Ride for enlightenment
 
Cheap Ryder's Avatar
 
Joined: Nov 2005
Location: Montana great divide
Oddometer: 550
Carb cleaning

I have been professionaly (getting paid by others) cleaning carbs since before the nighthawk was made. Do not just soak any old vacum piston carb set in cleaner or use the nastier carb/brake cleaner sprays. You can cause mucho problems. Take the float bowls off and clean the jets and emusifier tubes the main jets screw in to. Clean the float needles and make sure they shut off the gas. Check your diaphrams on the slides to see if they have any tears or holes. I glue up the holes with plastic and "right stuff" silicone type sealer. Check the anti backfire valves on the side of the carbs.....usaly there is one exposed but the others require splitting the carbs apart. If the one you can get to is OK the others should be. These diaphrams can be damaged by soaking in harsh cleaner.
The shop I am now working at has a ultrasonic cleaner and and a immersion cleaner which get used on the nastier carbs.
For those really plugged up idle or pilot jets use cheap Ryders trick.....use a metal scrup brush with the long bristles, about two inches long. lightly touch the end of a bristle to a grinder at a 45 degree angle. Then chuck up the plugged jet in your drill and spin the jet while pushing it down on your modified wire brush bristle. I have worked on probably hundreds of honda 90 carbs and other exotica in out of the way shops with no replacement parts and this cleaning method seems to work quite well.
Cheap Ryder is offline   Reply With Quote
Old 04-19-2012, 07:04 AM   #15
Boulder Ed
Bin Ridin
 
Boulder Ed's Avatar
 
Joined: Mar 2005
Location: A toyhauler marooned on mars, TX
Oddometer: 841
Carb restore

Excellent summary ... Soaking thes carbs intack would most likely damage lots of organic (rubber ) parts as that organic debris is what the solvents are designed to decompose. Sometimes a ittle does not hurt if it comes in contact, but you can literally see and feel the difference in rubber and plastic surfaces like float bowls that carb cleaning fluid comes into contact with.
One might then need to buy a bunch of costly carb kits/parts and may still never find all the little orings buried deep in the things. Most of the time it is simply the pilot jet, possibly a main jet and air passages cleaning that does the trick. The pilot and air fuel mixture circuit are coupled so both need to be removed to clean all the way through that critical passage is what someone recently advised me on one I was cleaning. It worked great after that, as the carb actually responded to changes in the air/fuel mixture...


Quote:
Originally Posted by Cheap Ryder View Post
I have been professionaly (getting paid by others) cleaning carbs since before the nighthawk was made. Do not just soak any old vacum piston carb set in cleaner or use the nastier carb/brake cleaner sprays. You can cause mucho problems. Take the float bowls off and clean the jets and emusifier tubes the main jets screw in to. Clean the float needles and make sure they shut off the gas. Check your diaphrams on the slides to see if they have any tears or holes. I glue up the holes with plastic and "right stuff" silicone type sealer. Check the anti backfire valves on the side of the carbs.....usaly there is one exposed but the others require splitting the carbs apart. If the one you can get to is OK the others should be. These diaphrams can be damaged by soaking in harsh cleaner.
The shop I am now working at has a ultrasonic cleaner and and a immersion cleaner which get used on the nastier carbs.
For those really plugged up idle or pilot jets use cheap Ryders trick.....use a metal scrup brush with the long bristles, about two inches long. lightly touch the end of a bristle to a grinder at a 45 degree angle. Then chuck up the plugged jet in your drill and spin the jet while pushing it down on your modified wire brush bristle. I have worked on probably hundreds of honda 90 carbs and other exotica in out of the way shops with no replacement parts and this cleaning method seems to work quite well.
__________________
Bin Ridin

"Terrorizing small animals on the road since 1971"
Boulder Ed is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
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 On

Forum Jump


Times are GMT -7.   It's 03:02 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014