Poll

What is the best method you have found to synch carbs on a 750?

Morgan Carb Synch tool
17 (48.6%)
Home-made manometer with mason jars & long tubes
1 (2.9%)
Commercially available mercury manometer
9 (25.7%)
Carb synch tool that does two at a time with a ball in a tube
1 (2.9%)
Cobbled together homemade device with 4 vac gauges.
4 (11.4%)
Some other device (post description please)
3 (8.6%)

Total Members Voted: 25

Voting closed: June 23, 2006, 09:08:12 PM

Author Topic: Carb sync  (Read 63641 times)

0 Members and 6 Guests are viewing this topic.

Offline Terry in Australia

  • Really Old Timer ...
  • *******
  • Posts: 33,674
  • So, what do ya wanna talk about today?
Re: Carb sync
« Reply #200 on: June 28, 2006, 09:36:24 PM »
Well to save my little corner of the environment, I'm working on making my own Bio-Gas to power the Zeppelin, I watched an interesting science program last night about a town in Sweden that runs all their public transport and many residents cars on the stuff, it is totally emission free, and they produce the gas from cow dung, so there's no chance of their dollars (Kroners?) going to the Arabs either.

Sadly for me there aren't too many cows in my yard, but I've got a dog, four cats, a wife and two sons, so I've started a program of covertly feeding them all food rich in chemicals that will contribute to a higher octane rated fuel. It's taking longer than I hoped though as 1 square yard of "waste" (poop) only produces about a litre of bio-fuel, and I've calculated that I'll need approx 24000 litres of gas to make the round trip to the US?

At the time of writing I've only managed to collect about 6 square inches of the stuff, mainly from the pets (and a few other pieces that I found while scouring the sidewalk last night after the program) as my family are either all mysteriously constipated, or possibly holding back the necessary raw materials required to produce some serious Bio-fuel. While I can understand  that they'll all miss me while I'm away delivering tools to needy sohc'ers, I think they need to look past this petty selfishness, and give me as much of that "Brown Gold" as they can reasonably produce.

Hmmnnn, well then I thought to myself, "why not ask for some help from my neighbours?" so I did a door-knock, which, in the calm light of day may not have been the best approach, as it was pretty dark, and I am a fairly imposing looking bloke, and being winter here I was wearing my heavy (but warm) camo combat jacket and ski-mask. I guess it's not that surprising that some of my "new to Australia" neighbours who are still coming to terms with the english language were somewhat confused when I knocked on their front doors at 10 pm asking that they "Give me all your #$%*". The response was mixed, and although I didn't manage to secure much in the way of raw materials again, I did for some reason end up with enough money to pay Mike for a new head and a set of CR carbs, and several nice cell phones, and even a very nice stereo which I guess I can use in the Zep?

Anyway, stay tuned folks, and I'll try to keep you all updated on my efforts to (eventually) make your wrenching a more affordable and ultimately more enjoyable, experience. In the meantime, if anyone can provide me with more raw material I'd really appreciate it, I read somewhere that Americans consume on average 100 acres of pizza per day, so I'm particularly interested in collecting the pizza by-product, as I believe that (depending on your choice of topping) that the bio-fuel produced from pizza alone would be perfect for powering my Zeppelin? Thanks in advance, Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline mrbreeze

  • Not your average
  • Really Old Timer ...
  • *******
  • Posts: 5,902
  • Shut up when you're talkin' to me!!
Re: Carb sync
« Reply #201 on: June 28, 2006, 10:11:01 PM »
Sorry I missed the poll but gotta say...Morgan Carb Tune all the way!!!(Hey..that ryhmed!!) Damn Terry,thats a hell of a story about your #$%* powered Zep! Please,please keep us informed.....later,,,The Breeze
MEMBER # 257
Fool me once..shame on you. Fool me twice..I'm kickin' your a$$......

Offline puppytrax

  • Expert
  • ****
  • Posts: 1,059
Re: Carb sync
« Reply #202 on: June 29, 2006, 06:13:54 AM »
...as my family are either all mysteriously constipated, or possibly holding back the necessary raw materials required to produce some serious Bio-fuel...

Just post an address...my ex-wife is full of "necessary raw materials"...and my refuse collection workers are getting annoyed at my heavy refuse bags/cans...I have a Doberman, a Weimaraner, and a mongrel Terrier who spend most of their waking moments depositing those raw materials that you hold so dear all around my back yard...

As to why a Zeppelin and not a Dirigible...I just like rigids better than gasbags...  ;)

A good movie with Zeps in it is "Zeppelin" with Michael York; an excellent book is "Winter" by Len Deighton. Fascination material about Zeps...I'm really surprised that no commercial enterprise has embraced them...[non-hydrogen, of course]...

To get back on-topic...I did ask if there was a Morgan distributor here in the US; can anyone who has bought one recommend anyone???
...stock 1972 CB500 '500 Four' undergoing re-assembly...
...Stock 1972 CL450 'Scrambler' also being re-assembled...

Offline Jeff.Saunders

  • Enthusiast
  • **
  • Posts: 236
  • Obsessed by Old Motorcycles
Re: Carb sync
« Reply #203 on: July 04, 2006, 08:47:08 AM »
Did anyone mention the new California laws that will take effect from July first?
These laws will make it impossible to buy mercury in California, and also other US states are following the California laws.
Since Motion Pro is a California based Company, they will not sell the Mercury sticks, at least not with mercury, anymore.

Hi Ivar - yes, we haven't been able to get any more of the mercury based sync tools for a few weeks now - and probably never will now.  Not such a bad thing given the negative impact Mercury has on the environment - I've always had mixed feelings about these tools.  Even with careful use, it's difficult to preserve the Mercury - just an accidental rise in rpms can cause the Mercury to get sucked out of the tool, ingested by the engine and spat out all over the garage / workshop - been there and done that

Californai was not the first state, apparently two other states already had laws on the books governing Mercury shipments.
As of July 1st, there are now 4 States with constraining laws on the books, with at least two more joining the legislation next year. 

MotionPro is continuing to manufacture a small number of the sync tools, but these will not ship with mercury - it'll be up to the customer to source Mercury if they want it.

Offline crazypj

  • I'm brill, me
  • Old Timer
  • ******
  • Posts: 4,468
  • first 100,000 miles. 1977 CB550F
Re: Carb sync
« Reply #204 on: July 04, 2006, 09:41:07 AM »
I'm probably with twotired, got a set of genuine Honda dial type gauges.
PJ
I fake being smart pretty good
'you can take my word for it or argue until you find out I'm right'

Offline hymodyne

  • Expert
  • ****
  • Posts: 1,302
Re: Carb sync
« Reply #205 on: August 03, 2006, 01:48:58 PM »
What exactly is the adjustment point under the top cover of cb 500/550 carbs for card synching? I've looked through threads and at the link for 750 carbs, but need the adjustment procedure for 500/550 carbs. Should inside cylinders be set to a different reading than those outside? ('72 cb500 K1)

hym
"All things are ready if our minds be so."

Offline StevieMac

  • Hot Shot
  • ***
  • Posts: 277
Re: Carb sync
« Reply #206 on: August 03, 2006, 01:53:11 PM »
I've got a '72 500 myself.

You can download the manual here: http://www.honda4fun.com/home.php

The idea is to get all 4 carbs to read the same on the guage.
72 CB500 Cafe
78 CB750 Chopper

Gallery: http://www.sohc4.us/gallery/v/members/personal/StevieMac/

Offline number13

  • Hot Shot
  • ***
  • Posts: 521
  • 1973 CB500, 2002 VT750DC
    • Sound Exchange
Re: Carb sync
« Reply #207 on: August 03, 2006, 02:06:14 PM »
The adjustment points for those carbs is the slotted head bolts
just outside each carb body, the ones with the lock nuts on them.
They are attached to the throttle rod and move with it.
Begin by loosening each locknut a couple of turns so you have soom
room to adjust. Start the bike and warm it up enough to idle at
1000 RPM, or as close as you can get to that. Using a small flat blade screwdriver,
twiddle the adjustment screws back and forth to get an even vacuum
across all four cylinders. The amount of vacuum isn't as important as EVEN
vacuum aal the way across, but my gauges usually read about 8 to 10 (kgs? inches? I can't remember!!)
When everything synchs up it is almost like tuning a guitar, you can easily hear
it. I use a four dial carb tool that taps into the intake manifolds with
screw in brass tubes, it works great!
 
LOL!
#13

Bikes parked out front mean good chicken-fried steak inside.

Offline DrMark

  • Hot Shot
  • ***
  • Posts: 263
Re: Carb sync
« Reply #208 on: August 03, 2006, 02:36:36 PM »
Can anyone show a picture of the correct screws to turn? I am also confused by the manuals. Would love to do these myself, but, I paid for someone else to synch my carbs the last 2 times.
1978 CB550K
1983 CB650SC Nighthawk

Offline number13

  • Hot Shot
  • ***
  • Posts: 521
  • 1973 CB500, 2002 VT750DC
    • Sound Exchange
Re: Carb sync
« Reply #209 on: August 03, 2006, 03:07:49 PM »
Give me day, I will get some photos up by tomorrow afternoon.
ALSO, forgot to mention you have to do this with the gas tank
off, you can't easily see the adjusters with the tank in place.
My bad.

#13
Bikes parked out front mean good chicken-fried steak inside.

Offline number13

  • Hot Shot
  • ***
  • Posts: 521
  • 1973 CB500, 2002 VT750DC
    • Sound Exchange
Re: Carb sync
« Reply #210 on: August 04, 2006, 12:00:16 PM »
Here's some pictures I took this afternoon, the first is a picture looking
down on the carb rack with the tank removed. the next two photos are
the left bank carbs number one and two, the third picture shows
carbs number three and four. The black arrow points to one adjuster screw.
Bikes parked out front mean good chicken-fried steak inside.

Offline number13

  • Hot Shot
  • ***
  • Posts: 521
  • 1973 CB500, 2002 VT750DC
    • Sound Exchange
Re: Carb sync
« Reply #211 on: August 04, 2006, 12:04:45 PM »
I use a four gauge synch tool, it comes with four brass tubes
which thread into the balance ports on each intake manifold,
between the carb and cylinder. The arrow in the photo
points to one port. Hope this helps!

regards,
#13
Bikes parked out front mean good chicken-fried steak inside.

shields102

  • Guest
Re: Carb sync
« Reply #212 on: August 04, 2006, 03:06:56 PM »
nice post number13.  I appreciate you taking the tme and posting the photos.  I am sure others will find these very useful.

Offline DrMark

  • Hot Shot
  • ***
  • Posts: 263
Re: Carb sync
« Reply #213 on: August 04, 2006, 03:11:02 PM »
Hey "13", now I'm really confused....I see that you are showing on an older CB550 carb....But according to the Honda Shop Manual, page 179, picture K3-15 ( I think for a 1977 & 1978 models) ....they are removing the silver top off of each carb and adjusting a screw inside of there?  What do you think?
1978 CB550K
1983 CB650SC Nighthawk

Offline number13

  • Hot Shot
  • ***
  • Posts: 521
  • 1973 CB500, 2002 VT750DC
    • Sound Exchange
Re: Carb sync
« Reply #214 on: August 05, 2006, 12:41:47 PM »
My bike is actually a 500 K2, but the carbs are mutts, I thought
they were from a 550, but I could be wrong. I have never
had to remove the tops to synch these carb, sounds like
yours are later that mine.
Bear in mind that all you are doing when synchronizing is simply
adjusting the the slide and, of course, the needle up and down,
so whatever the adjusting technique is,
you should look for that as a result.
Bikes parked out front mean good chicken-fried steak inside.

Offline nickjtc

  • I was numero dieci
  • Old Timer
  • ******
  • Posts: 4,210
  • Yamaha XT500 'Gromit'
Re: Carb sync
« Reply #215 on: August 05, 2006, 01:08:18 PM »
FYI here's how I sync the carbs on the 650, using this:

http://cgi.ebay.com/NEW-Motorcycle-Carb-Balancer-Synchroniser-Vacuum-Gauge_W0QQitemZ230014942070QQihZ013QQcategoryZ25623QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Pic 1: the overall set-up. The balancer hangs above the bike (to stop any part of it touching something hot and melting!), plugged into the vacuum outlet of two carbs. Carb #2 is the reference carb, and in this case I am working on Carb#1. The gas tank is off to the right, on a stand, set higher than usual and connected with a length of fuel line.

Continued on another post.
« Last Edit: August 05, 2006, 01:12:10 PM by nickjtc »
Nick J. Member #3247

2008 Triumph Tiger 1050
1977 Suzuki GS750

"That which does not kill us reminds us to wear proper motorcycle clothing...."

Offline bryanj

  • Really Old Timer ...
  • *******
  • Posts: 15,067
  • CB500 Number 1000036
Re: Carb sync
« Reply #216 on: August 05, 2006, 02:10:47 PM »
The only ones you have to remove the tops on are the 77/78 and they dont fit onto a 500 unless you fit the inlet manifolds as well and then the airbox dont fit, so look at your carbs closely to see what you have. Early carbs "coffin" shaped top with a screw on either side; 77/78 "P" shaped top with a screw at each end
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline kach_me

  • Hot Shot
  • ***
  • Posts: 312
Re: Carb sync
« Reply #217 on: August 05, 2006, 04:30:43 PM »
I've got a '72 500 myself.

You can download the manual here: http://www.honda4fun.com/home.php

The idea is to get all 4 carbs to read the same on the guage.

 ??? Don' speak Italian! Anyone have any idea where to get the manual for a CB750 1976? 
1976 CB 750K - Stock / No mods (yet).

Offline keiths

  • Hot Shot
  • ***
  • Posts: 393
Re: Carb sync
« Reply #218 on: August 05, 2006, 06:13:25 PM »
This should get you started.

Offline kach_me

  • Hot Shot
  • ***
  • Posts: 312
Re: Carb sync
« Reply #219 on: August 05, 2006, 07:25:41 PM »


Keith, the link you gave me is in either Italian or French, I don' know... can't read it.  The supplemental manuals are in English and are quite thorough on what they cover, but they don't cover everything.  Thanks anyhow! I'll keep looking...
1976 CB 750K - Stock / No mods (yet).

Offline Green550F

  • Hot Shot
  • ***
  • Posts: 339
  • Nothing is as cool as that which you made.
Re: Carb sync
« Reply #220 on: August 06, 2006, 12:15:41 AM »
Carb issues are a reocurring theme here! So when is someone going to develop a Fuel Injection swap for our fours? I mean most of the work is done, just look at a current CBR600/GSXR600 etc.  Ok, maybe I'm just wishing aloud again... ::)
93 Kawasaki Voyager XII
70 Honda CL350 Cafe

Offline g8ts

  • Full Member
  • *
  • Posts: 35
Re: Carb sync
« Reply #221 on: August 06, 2006, 07:44:52 AM »
This is a general write up on sync'ing. Maybe it will help !!!

http://www.crc2onlinecatalog.com/carb_synk.htm
"rebuild it rebuild it and rebuild it" 
quote from 30 year old Honda owners manual.
Good thing though, its good for another 30 years.
78 550 gone sent to friend in Germany
72 750 brown
73 750 Red
74 750 green
74 750 strange color extended forks
75 750 blue
75 500t sold
75 360 cl orange
77 750ss black
82 900c blue
83 650 CX black
Fence and herding dog to keep them all in.

Offline cmorgan47

  • Hot Shot
  • ***
  • Posts: 657
  • smaller, lighter, quicker
    • theundergr0und
Re: Carb sync
« Reply #222 on: August 07, 2006, 06:07:28 AM »
Carb issues are a reocurring theme here! So when is someone going to develop a Fuel Injection swap for our fours? I mean most of the work is done, just look at a current CBR600/GSXR600 etc.  Ok, maybe I'm just wishing aloud again... ::)

never. 
i'm starting to thing that learning carbs is a right of passage.
like a jedi building his own lightsaber.
i love babies...
with a nice chianti sauce and a side of fava beans

Offline super pasty white guy

  • I'm not really a
  • Expert
  • ****
  • Posts: 929
  • 1976 750 F
Re: Carb sync
« Reply #223 on: August 16, 2006, 09:55:32 AM »
So, someone tell me why this won't work. 

If I buy a single vacuum gauge and take a reading off of carb 1, and then adjust carbs 2, 3, and 4 to match haven't I synced?

It seems like it's the same as those devices that you sync carbs in pairs.  I know it'll be a bit of a pain, but it's just killin' me to spend that much $ on something I'll use so rarely.

DAve
Fruit don't talk, fruit just listens... and waits.

Offline Bob Wessner

  • "Carbs Suck!"
  • Really Old Timer ...
  • *******
  • Posts: 10,079
Re: Carb sync
« Reply #224 on: August 16, 2006, 10:27:59 AM »
I've always found that as you move back and forth between the carbs as you tune, the one's you've already tuned change and you have to go back and tweak them a bit, etc. Each affects the others. But then, I'm not a born wrench either.
We'll all be someone else's PO some day.