Carb Synch for the vacuum port-less

[montmil]

This article is from today's ABC list. Could be useful info for those with carbs lacking vacuum ports.
Monte

Sat, 5 Jun 2010
From: Thomas Marquardt <tmarquardt@gmail.com>
Subject: 0$ carb synchronizer (for the poor, and vaccuum-port-less)

All this talk about the $4 carb synchronizer has hurt my pride..., I
can only hope to afford one some day.    I've been using a 0$ carb
tuner.  Who else uses one of these?  For those that have never tried,
here's how it works.

Required Tools:

1. Ears
2. Hands
3. Screw driver

Synchronization Steps:

1. If you just rebuilt the carbs, set the fuel/air mixture screw at
the initial setting described in your manual (approximately 1 turn out
from all the way in, but depends on your model).

2. Go for the customary warm-up ride, described so well in other write-ups.

3. Park on the center stand, and don't run the bike for more than 7
minutes without going for a ride to cool it down, or it'll suck all
the money out of your bank account.

4. Ensure sufficient free-play in the throttle cables at the adjuster,
as described in other write-ups.

5. Adjust idle stop screws to set the idle (specified in other
write-ups, typically 1050 rpm) by listening with your ears and feeling
the tank with your hands, adjust both sides so it runs smooth at idle.
 It helps if you put your ears close to the cylinders on each side,
and stand behind the bike between the exhaust pipes and listen.
Should sound and feel the same on both sides.  Move it in one
direction 1/8 turn or so at a time...does it get better or worse?

6. Adjust fuel/air mixture screw to the spot in the middle where the
engine runs the best.  From this spot, if you turn the screw about 1/4
turn in or out, the engine will start to bog.  This is usually very
easy to notice, especially when you enrich the mixture too much, the
engine will bog.  Listen carefully for the first hint of the engine
beginning to slow.  Find the spot in the middle where it runs best,
not too lean, and not too rich.

[montmil]

7. You should probably go for a ride to cool down the engine.  If this
is your first time doing this, your 7 minutes are up.  You may need to
repeat steps 5 and 6, since 6 can impact 5 and vice-versa.  Dial it
in.

8. Now we're ready for the cables.  Loosen one of the cable adjusters.
Rev the engine briefly and increase the RPMs up to about 3500.
Listen to both sides and feel the vibration in the tank.  It can be
helpful to take it off the stand and sit on it while feeling and
listening.  Move the cable adjuster in either direction until you find
the smoothest spot, initially about 1/2 turn at a time, but later
smaller adjustments.  Make sure you have sufficient free-play in the
cable at the adjuster.  You may need to use the other adjuster
instead, if it has more free play.  By the way, put some grease in the
cable adjuster.

9. Now it should be silky smooth at 3500 rpm and above, but it might
not be smooth at 1500 or 2000 rpm, where the fuel/air mixture has an
effect.  If necessary, turn the fuel/air screw ever so slightly (1/8th
turn or less) on one side until the bike runs very smooth in the 1500
to 2000 rpm range, as you blip the throttle.

If my R60/6 had vacuum ports, I probably would have bought one of
those $4 tuners a while ago.  But if you take your time, use your
ears, and feel the vibration while sitting on the bike, you can dial
things in pretty well.  You have to understand the three parts: 1)
idle stop screws, 2) fuel/air mixture screws, 3) cable adjusters.  The
idle stop affects only the idle speed.  As soon as you twist the
throttle, the idle stop screw does nothing.  The fuel/air mixture
screw only has an effect at low RPMs.  To make things silky smooth,
adjust the cable adjusters while feeling the tank, sitting on the
bike, and listening as you twist the throttle.  Above approximately
3000 rpm, only the cable adjustment matters.  Once the cables are
adjusted, you may need to tweak the fuel/air mixture to get smoothness
in the lower RPM range.

[montmil]

By the way, it is assumed that everything
else is tuned (timing, valves, plug gap, floats, etc) before you start
messing with the carbs.

Cheers,
Thomas  -  Seattle, where we had an incredible sunny day today

...............

Rather lengthy but worthwhile information.   Monte

[montmil]

"Good stuff!  You can keep it all in one thread if you want. Copy the material from the 2nd thread, go into your 1st thread and just "reply" to your first post.  Then paste the info from the original 2nd thread. Do the same with the 3rd.

That way all the info stays in one thread and newbies like myself can find all the info in one place rather than dig to find three threads."

Graeme, you da bomb! Tried your "reply" idea and I done did it. As I'm not the most compuKer friendly sort I usually end up gerfunkin something. Thanks for the tip. [smiley=thumbup.gif]

Monte "Strike Any Key" Miller

[azcycle]

   Happy to help, Monte!

[Dizerens5]

If in doubt about low rpm synchro, remember it's surprisingly informative to just hold your hands an inch or two from the tailpipes and feel the pulse of the exhausts. Bad synchro will make quite a difference to the power of the left and right exhausts, despite the balance pipe.

[Patrick_Krivacka]

doe's anyone else use a fan for the cool down part? if so, do you use two fans for each cylinder, or one large one for both? I read about folks doin' both, just thought i'd see if anyone had any personal experience.

[Bob_Roller]

I use two 'box' fans, I got them cheap at Home Depot home improvement center a few years ago, at the end of the 'hot season' here, for about $15 each .

[montmil]

doe's anyone else use a fan for the cool down part? if so, do you use two fans for each cylinder, or one large one for both? I read about folks doin' both, just thought i'd see if anyone had any personal experience.

I personally gave up on the econo box fans years ago; they just didn't move enough air to suit me. Bit the bullet, financially, and spent $50.00 for a "real" fan that moves air throughout my work area.

For the Bing tweaking, I block the front wheel straight ahead and set up the fan just a few feet in front of the wheel. After roughing in the initial carb settings, it should be about a 4-5 minute tuning process, start to finish. Mixture screws, idle stop screws then cables. Done in that order. The idle circuit and idle stop screws r-e-a-l-l-y interact with one another.

Monte