Carb adjustment on Vulcaln Classic 800

Rich = more fuel in the air / fuel mixture
Lean = less fuel in the air / fuel mixture
more is usually better as factory setting is usually too lean

the only draw back to opening the screws (richening the mixture) is you
might get a couple of kilometres less per tank of gas

the draw back to having it too lean is eventual valve damage

my suggestion would be to open the mixture screw 1/2 turn at a time and try
for a day or two, if it isn't right then another 1/2 turn, BUT, becarefull
not to turn it all the way out and have it fall out while your drivin down
the road.

Larry


"Fitchin" wrote in message

 > My 2002 Vulcan Classic occasionally sputters and backfires through the
carb
 > while under load at low engine speed, (often when leaving a stoplight) and
 > was told I could alleviate this problem by adjustment of the idle mixture
 > screws on the carb.+
 >
 > Couple of questions here........
 >
 > I have read that they are factory set at about 1-1/2 turns open, and that
 > I'll eliminate this problem if I open them to about 3 turns. Has anyone
 > tried this?
 >
 > What does this do to the mixture? (rich or lean) and what do these terms
 > "rich" and "lean" mean?
 >
 > What are the consequences of running rich or lean. (I've heard about
burning
 > pistons before, not my idea of fun)
 >
 > What is the drawback to opening the screws to 3 turns?
 >
 > I'm very mechanically inclined so would have no problem doing this myself,
 > just looking for a little advice here.
 >
 > Thanks in advance for any help.
 >
 > Craig
 > 2002 Vulcan Classic
 >
 >


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.598 / Virus Database: 380 - Release Date: 28/02/2004
 >> Stay informed about: Carb adjustment on Vulcaln Classic 800 

Page answers with:

Sorry for the piggyback but I lost the original post. Best thing to try
to know for sure whether you are to rich or lean is to do a spark plug
chop test and read the plugs. That will let you know exactly what is
going on or have the bike dynoed to know positively for sure.

Dyno runs in the Dallas/Fort Worth Texas area can be made at Southwest
SuperBikes, ask Mark Peterson

Southwest Superbikes
Fabens Rd
(972) 418-0555 2361
Dallas, TX

To do a spark plug chop test, first put in a clean set of spark plugs in
an engine that is already warmed up to speed. Ride the bike at which
ever speed you want to test. Ride it for about 5 minutes at that speed
holding it steady. Reach up and shut the ignition off and cruise to a
stop on the side of the road. Pull the plugs out and examine them.
Black dull carbon buildup on the end = too rich
Oily shinny black buildup on the end = oil is slipping past your rings
White ash buildup on the end = too lean
No residue = set just about right.

To really do a good test you have to do four different speeds.
idle = idle circuit in the carb
1/8 to 1/4 = off-idle circuits
1/4 to 3/4 = needle circuit
3/4 to full = main jet circuit

Lastly check your enrichner system, air leaks, air filter, and float
system; these will all have an effect on the air/fuel mixture.

Things to watch for:
Lean mixture
1. Hesitation
2. Exhaust pops on declaration
3. Could run better with the enricher on
4. Idles erratically
5. Surges in speed at a constant throttle
6. Pipes turning excessively blue from excessive engine heat

Rich mixture
1. Runs rough
2. Blubbers
3. Could run better without an air filter
4. Runs better if you back the throttle off
5. Runs better with the fuel cut off - the lower fuel level in the
float bowl will lean out the mixture

Lare wrote:

 > Rich = more fuel in the air / fuel mixture
 > Lean = less fuel in the air / fuel mixture
 > more is usually better as factory setting is usually too lean
 >
 > the only draw back to opening the screws (richening the mixture) is you
 > might get a couple of kilometres less per tank of gas
 >
 > the draw back to having it too lean is eventual valve damage
 >
 > my suggestion would be to open the mixture screw 1/2 turn at a time and try
 > for a day or two, if it isn't right then another 1/2 turn, BUT, becarefull
 > not to turn it all the way out and have it fall out while your drivin down
 > the road.
 >
 > Larry
 >
 >


 >
  >>My 2002 Vulcan Classic occasionally sputters and backfires through the
 >
 > carb
 >
  >>while under load at low engine speed, (often when leaving a stoplight) and
  >>was told I could alleviate this problem by adjustment of the idle mixture
  >>screws on the carb.+
  >>
  >>Couple of questions here........
  >>
  >>I have read that they are factory set at about 1-1/2 turns open, and that
  >>I'll eliminate this problem if I open them to about 3 turns. Has anyone
  >>tried this?
  >>
  >>What does this do to the mixture? (rich or lean) and what do these terms
  >>"rich" and "lean" mean?
  >>
  >>What are the consequences of running rich or lean. (I've heard about
 >
 > burning
 >
  >>pistons before, not my idea of fun)
  >>
  >>What is the drawback to opening the screws to 3 turns?
  >>
  >>I'm very mechanically inclined so would have no problem doing this myself,
  >>just looking for a little advice here.
  >>
  >>Thanks in advance for any help.
  >>
  >>Craig
  >>2002 Vulcan Classic
  >>
  >>
 >
 >
 >
 > ---
 > Outgoing mail is certified Virus Free.
 > Checked by AVG anti-virus system (http://www.grisoft.com).
 > Version: 6.0.598 / Virus Database: 380 - Release Date: 28/02/2004
 >
 >


--
Page

'01 FXDWG, NTXNS
"Happy Hour" starts one twist of the throttle past neutral!
Remove the 123 to reply.
 >> Stay informed about: Carb adjustment on Vulcaln Classic 800 

The 1-1/2 turns thing is a sort of standard start point for any adjustment
screws on a carb, cars, chainsaws, lawnmowers... it's what you set them to
after you have stripped the thing down and forgot to make a note of where
they were

When and if you change screws on your carb(s), I really strongly suggest
that you get a notepad, screw the screw in all the way carefully counting
the exact revs, write it down, and then back it off to the new setting you
want to try. That way you can always put it back the way it was.

Changing these screws won't cause burned vlaves, because these screws only
affect close to idle situations. There are a bunch of things which can cause
burned valves, but idle mixture isn't one.

Before mucking with mixture screws on the carbs though, I would check just
about everything else. Check all to do with ignition and valve timing (like
valve clearances, they affect valve timing), manifold leaks etc. Even the
plugs, they should be the recomended heat range. The wrong heat range plugs
can cause all kinds of grief which could be diagnosed as something else.

If you get the feeling that I don't think the idle mixture screws on your
carb(s) are the problem, you're right.

There is some real good info on bike carbs at this link, I bumped into it
when I was researching rejetting my bike and saved it. I'm serious, this is
a good link....

<a rel="nofollow" style='text-decoration: none;' href="http://www.venturers.org/NextGenTech/2ndGen/pages/Carb101.html" target="_blank">http://www.venturers.org/NextGenTech/2ndGen/pages/Carb101.html</a>

Cheers

D.

"Fitchin" wrote in message

 > My 2002 Vulcan Classic occasionally sputters and backfires through the
carb
 > while under load at low engine speed, (often when leaving a stoplight) and
 > was told I could alleviate this problem by adjustment of the idle mixture
 > screws on the carb.+
 >
 > Couple of questions here........
 >
 > I have read that they are factory set at about 1-1/2 turns open, and that
 > I'll eliminate this problem if I open them to about 3 turns. Has anyone
 > tried this?
 >
 > What does this do to the mixture? (rich or lean) and what do these terms
 > "rich" and "lean" mean?
 >
 > What are the consequences of running rich or lean. (I've heard about
burning
 > pistons before, not my idea of fun)
 >
 > What is the drawback to opening the screws to 3 turns?
 >
 > I'm very mechanically inclined so would have no problem doing this myself,
 > just looking for a little advice here.
 >
 > Thanks in advance for any help.
 >
 > Craig
 > 2002 Vulcan Classic
 >
 >
 >> Stay informed about: Carb adjustment on Vulcaln Classic 800