V-Twin Carburetor Synchronization

On Jun 23, 11:08 pm, "Stupendous Man" <s....DeleteThis@trap.com> wrote:
> What kind of tool are you using? The mercury tube type gives excellent
> results, and the cheapest on from JC Whitney works as well as the nice one
> from Weber at the shop.
> Follow the factory manual instructions.
> --
> Stupendous Man,
> Defender of Freedom, Advocate of Liberty

Stupendous Man,
I'm using a DIY tool (I ordered Honda's tool, but it's about 10 days
out, and I need the bike to ride to work ). The setup I have is 20'
1/4ID tube bent in half with about 2' of 2-cycle oil in it. The
"display" part of the tubing is tied to a ruler. The inspiration was
this article: http://www.powerchutes.com/manometer.asp
Each side is connected to a carb. The theory is that if both carbs
were in sync, oil level in both halves would be the same (at least I
used that assumption to sync them) Just to make myself feel better, I
swapped the tubes and rechecked, and got the same reading.


Thank you
Yuriy
 >> Stay informed about: V-Twin Carburetor Synchronization 

Croosh wrote:

>Basically I'd like to know if it's a better idea to sync the carbs at
>higher RPM, say 2000 or so?

No way. How can you possibly synchronize carbs when you have plugged up idle
mixture ports and you're running on the transition ports instead?

When you turn the master idle knob down and you're back to running on the
single idle mixture port, the carbs will seem to be "out of synch" but the
real problem is crud in the passages, ports or the idle jet.

Have you drilled your EPA anti-tamper plugs out so you can remove the
idle mixture screws and do a proper chemical cleaning by getting the carb
cleaner to squirt out all six holes?

The holes are: idle mixture port, 3 transition ports, idle jet, and pilot air
jet.

In order to get the carb cleaner to squirt out the holes with the necessary
vigor to indicate the passages are clean, you have to squirt the aerosol
cleaner
into one hole, while covering all but one other hole with your fingers.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200706/1
 >> Stay informed about: V-Twin Carburetor Synchronization 

> out, and I need the bike to ride to work ). The setup I have is 20'
> 1/4ID tube bent in half with about 2' of 2-cycle oil in it. The
> "display" part of the tubing is tied to a ruler. The inspiration was
> this article: http://www.powerchutes.com/manometer.asp
> Each side is connected to a carb. The theory is that if both carbs

That should do a fine job, and you avoid that silly problem with mercury
when you chop the throttle and it gets sucked into the engine. I hate having
to hold my breath and run outside.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty
 >> Stay informed about: V-Twin Carburetor Synchronization 

Croosh wrote:

> Hello all!
> Have a quick question: I have a 2005 Honda Shadow 750, purchased used
> about a month ago. Previous owner did not winter the bike properly, so
> the carb needed to be cleaned etc. Both before and after the cleaning
> I was having afterfire issues with the rear cylinder (less so after
> the cleaning).
> Today I tried to sync the carbs (using a DIY sync tool). The rear
> cylinder had lot stronger vacuum, so I got both carbs synced at idle
> speeds. When I give it some throttle, front cylinder now has stronger
> vacuum (about 1/4 of what rear had before). Afterfire problem went
> away, and the bike idles a lot smoother, but at speed (4th gear at
> 45mph) it vibrates like nobody's business.
> Basically I'd like to know if it's a better idea to sync the carbs at
> higher RPM, say 2000 or so?
>
Not knowing squat about a Honda, but on my Moto Guzzi the carbs are
synchronized first at idle and then at 3000-4000 RPM or whatever my normal
cruise range is.

It is two different adjustments. First the sliders are set to equal height
on idle using one screw. Afterwards, the sliders are synchronized while the
throttle is turned using a different screw.

I also use the "High Tech Oil Tube" synchronization equipment and that is a
great an easy-to-use tool. Takes me about 5 minutes to synchronize.


Regards,
Bjarne
 >> Stay informed about: V-Twin Carburetor Synchronization 

On Jun 23, 10:36 pm, Croosh <ycro....DeleteThis@gmail.com> wrote:
> Hello all!
> Have a quick question: I have a 2005 Honda Shadow 750, purchased used
> about a month ago. Previous owner did not winter the bike properly, so
> the carb needed to be cleaned etc. Both before and after the cleaning
> I was having afterfire issues with the rear cylinder (less so after
> the cleaning).
> Today I tried to sync the carbs (using a DIY sync tool). The rear
> cylinder had lot stronger vacuum, so I got both carbs synced at idle
> speeds. When I give it some throttle, front cylinder now has stronger
> vacuum (about 1/4 of what rear had before). Afterfire problem went
> away, and the bike idles a lot smoother, but at speed (4th gear at
> 45mph) it vibrates like nobody's business.
> Basically I'd like to know if it's a better idea to sync the carbs at
> higher RPM, say 2000 or so?
>
> Thank you in advance
> Yuriy

Are you sure your throttle linkages are well synced ?
Sounds like you might be opening one carb early.

You might also be off the idle jet at that point and
running on the needle jet, which is a whole different
set of tuning adjustments.

I generally like to sync my carbs using plug shorting rather
than vacuum. Using a 4mm tap, a couple of 1/8" ID aluminum
spacers and a couple of 4mm bolts, I made up an extension
between the plug lead and spark plug.

With a narrow band tach attached to the engine, you
short out first one plug then the other and compare
engine RPMs. After adjusting the idle speed, it's
easy to lock the throttle at 2000 or so and compare
RPMs again.

If it's OK at idle but off at 2000, I'd figure that either the
throttles weren't synced well or perhaps I had one needle
set incorrectly. You should also take a long hard look
for air leaks. Anything loose or leaky will throw
your tuning off completely.
 >> Stay informed about: V-Twin Carburetor Synchronization 

On Jun 24, 1:58 am, "Albrecht via MotorcycleKB.com" <u33665@uwe>
wrote:

> When you turn the master idle knob down and you're back to running on the
> single idle mixture port, the carbs will seem to be "out of synch" but the
> real problem is crud in the passages, ports or the idle jet.

If the two cylinders are drawing different amounts of vacuum,
that's not a jetting problem. If it's not running evenly, it might
be jetting, but he's talking about a vacuum imbalance.
I started to make the same mistake myself in another post.

Vacuum imbalance would be idle speed adjustment,
throttle adjustments, cylinder compression, air leak(s),
torn diaphragm and/or faulty measurement tool.

Did I forget anything ?
 >> Stay informed about: V-Twin Carburetor Synchronization 

Just trade it in for a Suzuki Savage and you'll never have this
problem again

The cheapo JC Whitney one works fine. Mine's around somewhere. I
hope it still has Mercury in it. Otherwise, the cat drank it...

Charles
 >> Stay informed about: V-Twin Carburetor Synchronization 

This message is not archived
 >> Stay informed about: V-Twin Carburetor Synchronization 

On Jun 25, 12:34 pm, Rob Kleinschmidt <Rkleinsch1216....RemoveThis@aol.com>
wrote:
> On Jun 23, 10:36 pm, Croosh <ycro....RemoveThis@gmail.com> wrote:
>
>
>
>
>
> > Hello all!
> > Have a quick question: I have a 2005 Honda Shadow 750, purchased used
> > about a month ago. Previous owner did not winter the bike properly, so
> > the carb needed to be cleaned etc. Both before and after the cleaning
> > I was having afterfire issues with the rear cylinder (less so after
> > the cleaning).
> > Today I tried to sync the carbs (using a DIY sync tool). The rear
> > cylinder had lot stronger vacuum, so I got both carbs synced at idle
> > speeds. When I give it some throttle, front cylinder now has stronger
> > vacuum (about 1/4 of what rear had before). Afterfire problem went
> > away, and the bike idles a lot smoother, but at speed (4th gear at
> > 45mph) it vibrates like nobody's business.
> > Basically I'd like to know if it's a better idea to sync the carbs at
> > higher RPM, say 2000 or so?
>
> > Thank you in advance
> > Yuriy
>
> Are you sure your throttle linkages are well synced ?
> Sounds like you might be opening one carb early.
>
> You might also be off the idle jet at that point and
> running on the needle jet, which is a whole different
> set of tuning adjustments.
>
> I generally like to sync my carbs using plug shorting rather
> than vacuum. Using a 4mm tap, a couple of 1/8" ID aluminum
> spacers and a couple of 4mm bolts, I made up an extension
> between the plug lead and spark plug.
>
> With a narrow band tach attached to the engine, you
> short out first one plug then the other and compare
> engine RPMs. After adjusting the idle speed, it's
> easy to lock the throttle at 2000 or so and compare
> RPMs again.
>
> If it's OK at idle but off at 2000, I'd figure that either the
> throttles weren't synced well or perhaps I had one needle
> set incorrectly. You should also take a long hard look
> for air leaks. Anything loose or leaky will throw
> your tuning off completely.- Hide quoted text -
>
> - Show quoted text -

Rob,
My carb has only one side connected to the throttle cable (the rear
one to be exact), and the front one is connected through rigid lincage
(also featuring the screw used to sync the carbs).
On my ride to work yesterday the bike hated life at 50MPH. It was
vibrating like I can't describe...

I messed little more with it. Instead of using the "manometer", I took
the bike for a ride with loan mower gas tank (so I had access to the
sync adjustment screw). I did my best to tune it by feel (OK idle, and
less vibration at speed). While the motor appears to work "smoother",
vacuum is way out of wack now
I checked the whole intake manifold for leaks/loose connections, and
everything looks fine as near as I can tell.

What would be the next thing to do? Panic, take my medicine and take
the bike to my friendly neighborhood Honda Stealer?

Thank you
Yuriy
 >> Stay informed about: V-Twin Carburetor Synchronization 

> What would be the next thing to do? Panic, take my medicine and take
> the bike to my friendly neighborhood Honda Stealer?
>

Have the valves been adjusted? Is the compression equal? Are the plugs and
plug wires any good? Have you opened the carb bowl drains to check for
water?
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty
 >> Stay informed about: V-Twin Carburetor Synchronization 

On Jun 27, 12:00 am, Croosh <ycro....DeleteThis@gmail.com> wrote:
> On Jun 25, 12:34 pm, Rob Kleinschmidt <Rkleinsch1216....DeleteThis@aol.com>
> wrote:
>
>
>
> > On Jun 23, 10:36 pm, Croosh <ycro....DeleteThis@gmail.com> wrote:
>
> > > Hello all!
> > > Have a quick question: I have a 2005 Honda Shadow 750, purchased used
> > > about a month ago. Previous owner did not winter the bike properly, so
> > > the carb needed to be cleaned etc. Both before and after the cleaning
> > > I was having afterfire issues with the rear cylinder (less so after
> > > the cleaning).
> > > Today I tried to sync the carbs (using a DIY sync tool). The rear
> > > cylinder had lot stronger vacuum, so I got both carbs synced at idle
> > > speeds. When I give it some throttle, front cylinder now has stronger
> > > vacuum (about 1/4 of what rear had before). Afterfire problem went
> > > away, and the bike idles a lot smoother, but at speed (4th gear at
> > > 45mph) it vibrates like nobody's business.
> > > Basically I'd like to know if it's a better idea to sync the carbs at
> > > higher RPM, say 2000 or so?
>
> > > Thank you in advance
> > > Yuriy
>
> > Are you sure your throttle linkages are well synced ?
> > Sounds like you might be opening one carb early.
>
> > You might also be off the idle jet at that point and
> > running on the needle jet, which is a whole different
> > set of tuning adjustments.
>
> > I generally like to sync my carbs using plug shorting rather
> > than vacuum. Using a 4mm tap, a couple of 1/8" ID aluminum
> > spacers and a couple of 4mm bolts, I made up an extension
> > between the plug lead and spark plug.
>
> > With a narrow band tach attached to the engine, you
> > short out first one plug then the other and compare
> > engine RPMs. After adjusting the idle speed, it's
> > easy to lock the throttle at 2000 or so and compare
> > RPMs again.
>
> > If it's OK at idle but off at 2000, I'd figure that either the
> > throttles weren't synced well or perhaps I had one needle
> > set incorrectly. You should also take a long hard look
> > for air leaks. Anything loose or leaky will throw
> > your tuning off completely.- Hide quoted text -
>
> > - Show quoted text -
>
> Rob,
> My carb has only one side connected to the throttle cable (the rear
> one to be exact), and the front one is connected through rigid lincage
> (also featuring the screw used to sync the carbs).
> On my ride to work yesterday the bike hated life at 50MPH. It was
> vibrating like I can't describe...
>
> I messed little more with it. Instead of using the "manometer", I took
> the bike for a ride with loan mower gas tank (so I had access to the
> sync adjustment screw). I did my best to tune it by feel (OK idle, and
> less vibration at speed). While the motor appears to work "smoother",
> vacuum is way out of wack now
> I checked the whole intake manifold for leaks/loose connections, and
> everything looks fine as near as I can tell.

Check your compression. I went through the same exercise
a while back, only to find compression was way down on one
cylinder and everything I did to the carbs was just trying to
put bandaids on the problem. I really needed a valve job very
badly. It could also be that the valves are just way out of
adjustment. Check that before you dick with the carbs any more.

While I was farting around with the carbs, I actually got them
pretty well synced before ever installing them on the bike.

On the workbench, I mickey moused up a setup with a vacuum
cleaner sucking air through the carb. I used a roll of electric
tape to make a bushing to fit the vacuum cleaner hose
into the rubber carb throat where it normally runs into the
head. I used a piece of clear plastic with a small hole to
block off the other end of the carb to create a vacuum while
letting me look at the carb slide.

I got things adjusted so the two slides opened equally, then
marked the idle screws so I could turn them equal amounts
on the bike.

That's when I discovered the carbs were a waste of time
and I had valve problems.

> What would be the next thing to do? Panic, take my medicine and take
> the bike to my friendly neighborhood Honda Stealer?

Check compression. Try spraying WD40 or carb cleaner
around the outside of the carb to see if the RPM changes
(air leak if it does). Try plug shorting to tune the bike.
Find a knowledgeable independent or take it to a dealer.
 >> Stay informed about: V-Twin Carburetor Synchronization 

On Jun 26, 2:03 pm, chas <chass....RemoveThis@gmail.com> wrote:
> Just trade it in for a Suzuki Savage and you'll never have this
> problem again

Yes. Especially as a bike ages. It's *so* nice to never need to sync.
--
Rayvan
 >> Stay informed about: V-Twin Carburetor Synchronization 

In article <1182969323.383503.190260.DeleteThis@o61g2000hsh.googlegroups.com>,
Rob Kleinschmidt <Rkleinsch1216128.DeleteThis@aol.com> wrote:

> Check your compression. I went through the same exercise
> a while back, only to find compression was way down on one
> cylinder and everything I did to the carbs was just trying to
> put bandaids on the problem. I really needed a valve job very
> badly. It could also be that the valves are just way out of
> adjustment. Check that before you dick with the carbs any more.
>
> While I was farting around with the carbs, I actually got them
> pretty well synced before ever installing them on the bike.
>
> On the workbench, I mickey moused up a setup with a vacuum
> cleaner sucking air through the carb. I used a roll of electric
> tape to make a bushing to fit the vacuum cleaner hose
> into the rubber carb throat where it normally runs into the
> head. I used a piece of clear plastic with a small hole to
> block off the other end of the carb to create a vacuum while
> letting me look at the carb slide.
>
> I got things adjusted so the two slides opened equally, then
> marked the idle screws so I could turn them equal amounts
> on the bike.

Hey, that's really neat.

> That's when I discovered the carbs were a waste of time
> and I had valve problems.
>
> > What would be the next thing to do? Panic, take my medicine and take
> > the bike to my friendly neighborhood Honda Stealer?
>
> Check compression. Try spraying WD40 or carb cleaner
> around the outside of the carb to see if the RPM changes
> (air leak if it does).

Carburetor cleaner is probably a better idea. It doesn't leave a sticky
or greasy residue.

> Try plug shorting to tune the bike.

I'm not sure I like that. :/

> Find a knowledgeable independent or take it to a dealer.

Always a good final alternative. }: )

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
It's easy to say a war is so important your neighbor should go fight it for you.
 >> Stay informed about: V-Twin Carburetor Synchronization