DIY Carburetor Synchronize / Balance Tool
This is a homemade bottle style carburetor synchronization tool ( homemade
manometer ) and balancing tool. If you are going to attempt to, or want to
know how to sync your carburetors, there are a few things to know first.
1. Carburetor Synchronization = Adjusting your carburetor throttle plates
or throttle slides so they move from your carburetors idle setting to wide
open throttle simultaneously, or in sync with each other.
2. Balancing Carburetors = Adjusting your carburetors so they allow each
cylinder to flow or pull the same amount of air and fuel at your desired
idle speed. Carburetor sync and carburetor balancing go hand in hand.
3. Idle speed screw adjustments must be made at normal operation
4. Air fuel mixture screw adjustments must be made at normal operating
5. Air fuel mixture adjustments only affect your carburetors pilot circuit,
which means from idle to part throttle. Air fuel mixture screw adjustments
have zero effect on wide open throttle.
6. Carburetor running rich = Too much gas not enough air.
Carburetor running lean = Too much air not enough gas.
7. Wide open throttle rich or lean conditions are adjusted two ways:
A. Carburetors with throttle slides have a clip on the carburetor main
jet needle. Raising the main jet needle clip drops the needle deeper into
the main jet and will lean the carburetor out. Lowering the main jet needle
clip will raise the needle and enrich your carburetors mix.
B. Carburetors with throttle plates (butterfly style) need to have the
carburetors main jet changed to a larger diameter jet to richen the mix or
a smaller diameter jet to lean your mix.
8. If your engine will not idle correctly or your air fuel mixture screws
seem to have no affect on the engine at idle, then most likely your pilot
jet circuit is clogged and you should clean it.
The snowmobile in the video is a 1986 Arctic cat cougar 500 fan cooled, it
has Mikuni vm34 roundslide carburetors which have a primer nipple on the
engine side of the throttle slide. Perfect place to attach a homemade
manometer to balance everything. These mikuni vm34 roundslide carburetors
were common on many motorcycles, snowmobiles and atv's. Suzuki, yamaha,
polaris, arctic cat, all used them at one time or another, they are good
carburetors when they are dialed in.
VW DUAL PORT CROSS FIRE INTAKE SYSTEM
Replaces dual carbs.. and messy linkage.Cuts maintenance costs in
half..tons of room for plug removal and replacement. fits in a bus or bug
with clearance for the deck lid.sounds better than duals.. and has crisp
throttle response at any rpm .. no flat spots even with a oo9 dist, comes
to order with your carb base pattern. works well at 40 degrees temps and
above . do people actually drive their bugs and busses at night? easy
Homemade 4 Cylinder Carburetor Synchronizer/Manometer
An extended video of my homemade manometer with detailed explanations and
demonstrations of it in operation. Very inexpensive yet very accurate. I
used Snapple bottles which worked fine, but if you can get taller bottles
that would be better as it gives you more time to fix a severely
out-of-sync cylinder before a bottle runs dry. You'll notice my design
links all 4 cylinders together to give you true comparison across all 4
Since it's been asked: if you get air in the reservoir line simply
blow/suck on one of the cylinder lines until all air bubbles are gone; just
like if a bottle goes dry, etc.
And for the carburetor adapters, you can make your own (see my comment in
the comments section) or buy them here:
Here's a list of required materials:
4 Glass bottles
4 Rubber Stoppers
4 plastic 'tees'
20'-25' clear tubing
4 intake port adapters (specific to your bike make/model)
Tip: put the stoppers in the freezer for a while before trying to drill the
holes for the tubing and it will drill much cleaner.
Dellorto / Weber secrets #4
EZ Demonstration of how to find a blocked idle jet on car with engine
running. At my channel page I will have my Dellorto / Weber carburator vids
on a play list for EZ viewing.