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From: Albrecht via MotorcycleKB.com on 15 Jun 2007 17:00
billybuckshot(a)gmail.com wrote:

>Somehow the engine is getting too much fuel. I can turn the mixture
>screw in all the way and it doesn't affect the idle.

The fact that the idle mixture screw has an o-ring on it indicates to me that

it's a gas screw, but I could be wrong for the first time in my life. ;-)

What happens if you turn the idle mixture screw counterclockwise about two
or three turns?

>On other carburetors i've worked on this tells me i am getting too much fuel
>through the pilot jet, but i can't seem to find any smaller jets for
>this cv carb.

Yes, the typical CV carb has an idle mixture screw that controls the fuel/air
mix
after it has mixed, instead of controlling the amount of air add to the mix
like the
old slide valve carbs.

It's possible that the tips of your idle mixture screws have been broken by
rough
treatment, you might consider replacing them.

http://www.oldbikebarn.com/images/products/KL-18-2419.jpg

Or http://street.parts-unlimited.com/23/93/4086994

Each kit contains all necessary gaskets, O-rings and jets to rebuild one OE
carb

18-2419 FITS MODEL: CB450/CL450K1 to K4 68-71 $21.95

Typically, a CV carb will have idle jets that range from #35 to #42.5.

The carbs with #35 idle jets need to have the idle mixture screws turned out
2.5 to 3.0 turns.

But the fuel flow through a #42.5 idle jet is almost twice as much, so the
idle mixture screws
only need to be turned out about 1/4 of a turn.

I see from the CB500 carburetor diagram that it used #35, #38, or #40 idle
jets. They are probably
ordinary Keihin round idle jets.

> is there a problem with these carbs where the cv slide fails to raise and
>lower properly? i know the later kehin cv carbs have a rubber diapragm
>to aid the vacuum slide.

I have heard of sticky pistons on old Honda carbs, but the rubber diaphragm
slides stick too.
When that happens, the engine is doggy at idle and won't respond to the
throttle because the slide
won't raise up and richen the midrange mixture.

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From: The Older Gentleman on 15 Jun 2007 17:04
<billybuckshot(a)gmail.com> wrote:

> the problem is if i buy another set off e-bay from some m/c
> junkyard, chances are i'll have the same problem.

You're probably right.


--
BMW K1100LT 750SS CB400F CD250 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
From: MadDogR75 on 15 Jun 2007 17:23
On Jun 15, 1:18 pm, billybucks...(a)gmail.com wrote:
> I'm having a difficult time getting a friends Honda Cl450 to quit
> fouling plugs. I'm familiar with vintage HDs and Brit bikes but this
> old Honda is making me tear my hair out. I've cleaned the carbs
> thoroughly and rebuilt them with new jets, readjusted the valves,
> checked the points, compression (140 psi) but the bike fouls the plugs
> (black soot) within 10 minutes of start up. Other than replacing the
> carbs completely, i'm out of ideas. Anyone out there familiar with
> these old Hondas? Help is greatly appreciated. -Billy

Probably an idle though after all this:
"Are you sure you've got the proper heat range on those plugs?"

From: billybuckshot on 15 Jun 2007 19:16
On Jun 15, 4:23 pm, MadDog...(a)yahoo.com wrote:
> On Jun 15, 1:18 pm, billybucks...(a)gmail.com wrote:
>
> > I'm having a difficult time getting a friends Honda Cl450 to quit
> > fouling plugs. I'm familiar with vintage HDs and Brit bikes but this
> > old Honda is making me tear my hair out. I've cleaned the carbs
> > thoroughly and rebuilt them with new jets, readjusted the valves,
> > checked the points, compression (140 psi) but the bike fouls the plugs
> > (black soot) within 10 minutes of start up. Other than replacing the
> > carbs completely, i'm out of ideas. Anyone out there familiar with
> > these old Hondas? Help is greatly appreciated. -Billy
>
> Probably an idle though after all this:
> "Are you sure you've got the proper heat range on those plugs?"


To answer everyones questions: i failed to mention that i replaced the
mixture screws. that didn't help. i also inspected where they seated
and the was no noticable damage.
i've also been through about 6 sets of NGK B8ES plugs, that are
constantly being cleaned in the bead blaster and returned back to the
rotation. I've also tried hotter B7ES plugs, no difference.

From: Albrecht via MotorcycleKB.com on 15 Jun 2007 20:44
billybuckshot(a)gmail.com wrote:

>To answer everyones questions: i failed to mention that i replaced the
>mixture screws. that didn't help. i also inspected where they seated
>and the was no noticable damage.
>i've also been through about 6 sets of NGK B8ES plugs, that are
>constantly being cleaned in the bead blaster and returned back to the
>rotation. I've also tried hotter B7ES plugs, no difference.

The only carburetor-related thing I can think of is high fuel level in the
float bowls, making it too easy for the engine to suck up gasoline at idle
RPM.

When you set the floats at 20mm, were you measuring from the aluminum body of
the carburetor, or were you measuring from the paper float bowl gasket?

If the gasket is stuck to the carburetor body and you don't want to disturb
it, subtract 1mm from the nominal float height.

Do you get a nice fat 1/4-inch long blue spark when you hold the lead next to
the spark plug while the engine is idling?

Do the spark plug electrodes show that the spark has been jumping from all
over the center electrode? That would eliminate low ignition voltage as a
problem.

Does the ignition advancer work?

--
Message posted via MotorcycleKB.com
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