Carb Syncing - DIY Manometer vs "sound and feel"

[79josh81]

^^^That's awesome^^^^

I knew it was going to be better from everything I had read but I had no idea it was going to be as solid as what it ended up being. Super happy. Now if it'd stop snowing around here I could actually enjoy this build. Thanks again guys.

 

[gggGary]

Old school; have a 4 gauge set, works great once you understand and use the throttling valves located at the base of each gauge. Don't even want to think about the misadventure the LAST time I tried a mercury stick set.

 

[79josh81]

Lol

 

[fredintoon]

Old school; have a 4 gauge set, works great once you understand and use the throttling valves located at the base of each gauge. Don't even want to think about the misadventure the LAST time I tried a mercury stick set.

View attachment 131140

Hi Gary.
my aging brain dimly remembers a 4-way set that looked and worked just like a Mercury stick unit but used shiny steel rods instead.
One of those wouldn't have any Mercury to spill and make you "As mad as a hatter" eh?

 

[grizld1]

You're thinking of the Morgan Carbtune manometer, Fred. They're still made in both 2-column and 4-column sets, and I've used a 2-column set for years. The best price is from the manufacturer in England. Shipping to North America is surprisingly fast and cheap.

 

[pjc]

Since it's gotten so cold outside limiting what garage work I can do to my XS project I've been working inside on projects for when it's better temps outside. Following examples on the site I made an oil manometer. Also shopped at GoodWill for an aluminum tank for remote gas container. Got the bobbed seat project (for an '80 SG) going on too.
I used a plastic T fitting for bottom 180° turn for clear tubing. Have a rubber plug over open end, can draw the oil up into tubing when I use the mano, drain when I'm done. I was going to put a valve into one line going to carb vac port so when I start engine if balance is way off I don't suck oil into the expansion chambers. Instead I'll just use a bulldog clamp to pinch the tube near the carb vac port. Used 1/4 inch tube for the mano, reduced to 3/16 inch at the carb vac port end. Probably could have used 3/16 for the entire project.

 

[5twins]

That's an interesting take on the manometer design. I never saw those "expansion" chambers near the top like that. Let us know how that works. Are those clamps you used to attach the tubing to the stick readily available? They look like just what's needed.

 

[pjc]

The clamps came from local farm-n-barn. Lots of hardware departments have the specialty fasteners & stuff drawers that clamps, bushings, fittings, etc. are available.

I saw the expansion chamber idea here http://www.xs650.com/threads/homemade-carb-sync.2317/page-5#post-417944 (post #83) posted by TwoManyXS1Bs. It prevents engine from digesting a slug of oil, etc, if balance is way off or some other foul thing happens.

I've about $20 invested in the mano.

 

[aldo5468]

You know what made the Mad Hatter mad

 

[Ozboy]

You're thinking of the Morgan Carbtune manometer, Fred. They're still made in both 2-column and 4-column sets, and I've used a 2-column set for years. The best price is from the manufacturer in England. Shipping to North America is surprisingly fast and cheap.

I just got the four colum Morgan Carbtune and it is a brilliant bit of kit in a nice case.
Super fast shipping to Australia at a reasonable price. Opted for the four tuner as you never know one day i might need it.
I had one carb drawing way too much during sync and i was sick of of my home made manometer. Using the twin bottle system i seen videos online looks good but the Morgan is so compact and easy to use. Get and aux fuel bottle and sync can be done in minutes!

 

[Paul Sutton]

Regarding homemade manometers: If you are concerned about the fluid in the manometer getting sucked into the engine, or the fluid you chose foams, or the readings are erratic, then insert a restriction into the ends of the manometer. I used 6mm plastic toy BBs with a 1mm hole drilled through them. The details and pictures are given in Entry 8 of the following thread:

http://www.xs650.com/threads/screw-adjust-vacum-carb-xs650e.52814/#post-560823

 

[Ozboy]

Restriction wont stop a large vaccum difference i was seeing it just slows the large flucuations to a more stable level to sync more closely.

 

[Paul Sutton]

Restrictions will give you sufficient time to adjust or switch off the motor. Will also substantially slow the rate that the fluid will pass. Also, any large differences should have been taken care off by syncing the carburetor on the bench using a light source, paper, or fine copper wire.

 

[TwoManyXS1Bs]

Just a trivial FYI thing.
Back in the daze, we used dial type guages, like this.


Not only to check synchronization, but to help diagnose during tune ups. By watching the needle fluctuations at different rpms and throttle positions, you could isolate and diagnose an individual cylinder, and/or tweak the sync to even things out, smoother running. Similar to this chart, but different, as this chart is for an automotive multi-cylinder with a single manifold.


We had a chart for the Honda CB750, but I haven't seen one on the web...

 

[xjwmx]

Oh yes. Cuz you know how wack gravity is. With the way it effects ocean tides and all. I'd go with the Chinese made tools every time!

Gravity is what makes me not do what I don't need to do
If you were taking measurements, and they had to be precise, then maybe some instrument other than HF. But not homemade, still. But you don't need precise measurement, you only need to see if two things are the same -- meter could be 90% off and it wouldn't matter.