Homemade manometer troubles?

I built a manometer that is basically like the one at the bottom of the page on this thread (on another cycle forum). It's just four tubes interconnected at the bottom filled and with ATF that are connected to the vacuum tubes on the intake manifolds. It seems simple enough but I'm having trouble syncing my carbs with it.

Once I have the bike warmed up and the tool connected, I start making adjustments - bring #4 up to match #3, then match #1 & #2, then try to line up the two pairs using the middle sync screw. Every time that I've just about got it, the engine suddenly starts to race and everything goes haywire.

I tried it twice using my homemade YICS tool but was uncertain whether or not that might have been the problem. So, today I tried the Mystery Oil-soaked cloth strip packed into the YICS gallery instead. Same result.

Now I'm wondering if the design of the manometer itself might be flawed. Seems simple enough but I'm not an engineer. Has anyone had a similar experience?

 

As you sync, you need to keep the bike at idle. As you get your bike closer to ideal wrt pilot mixtures and syncing, cylinders will start to work together instead of over compensating for one another. So your "idle" speed will increase. Try to back off the idle using the idle speed screw underneath your carbs between #2 and #3 bowls to bring it down to the recommended idle speed (I think I saw that this is 1200 rpm - but I don't have one so I don't know)

How did you set your pilot mixture screws?

 

keep that idle speed knob handy, as they come into sync the idle will come up
with a setup like that one there's not much time to get to the idle knob
just tweek it in a little at a time and keep turning the idle down

 

When you closely examine some of the contraptions that have been employed as homemade manometers; there ought to be a Rube Goldberg Award for a few our Members have created.

You're wondering about the design of the homemade manometers being flawed.

Other's are wondering about the DESIGNER of the homemade manometer being flawed.

Hey, Rick?
Who's Rube Goldberg?

He drew Cartoon "Machine's" that made people laugh.
Like this one: ⬇

Pass GO --- Collect $200 --->:
http://www.youtube.com/watch?v=qybUFnY7 ... _embedded#!

 

Good find! I was going to offer a Rube Goldberg link to it only to find we were thinking of the same link. This is one fun video.

BTW, did you see the note where I found the errant bearing? It was resting on the top of #2 cylinder, next to the plug. So now they're all accounted for!

Thanks again for your fine work!

 

saw that video a couple months ago when my boss showed it to me. the song sucks but the machine is just amazing. i can only imagine how many tries it took to get it perfect.

 

Hey Bay, how much of a turn are you making on the screw?
Any more then a dime or so at a time can throw them way off.

 

Weird problem. Are you sure you don't have an airleak somewhere?

I used my homemade sync tool a couple of times without any problems. Just don't forget to plug the hoses that you pulled of.

 

I'm not sure how much "a dime" is in the context of turning a screw, but I'm making a small adjustment and watching the levels of the manometer tubes, then making another very small adjustment, etc.

 

Where would such a leak be? If I have one, I seriously doubt it be in the manifolds. They are brand new with black RTV on both sides of the gaskets plus a little silicone grease where the carb throats attach. Clamps are tightened down all the way.

 

We're speaking of the edge of the coin.
I could measure the width of a dime with calipers and give you
distance in numbers-but I have't had my coffee yet lol.
It's just quicker to express the measurment in a size everyone
is familiar with. i.e. width of a dime/nickel/quarter..so on.
( I stole the phrase from Rick only because of convinience).

 

So that pretty much rules out an air leak.
Only thing that comes to mind is that when the carbs are close to eachother (vacuum-wise) the rpm's go up.
Turn out the idle screw all the way. That way the engine will probably stall, but (if everything else is ok) your idle won't go haywire (like that word. never heard of it :roll: )

 

Leaks can also appear from the shaft seals.

 

Replaced those during the rebuild, too!

 

Because these Mikuni's are acting so stubbornly as the IDLE and SYNC are trying to be set, ...

This situation might need to have the Main AIR and PILOT Mixture Circuit ... "Power Flushed"

Using a Bubble Ear Cleaning Syringe.



Spray Carb Cleaner into a Jar and collect the fluid.
Squeeze the Syringe and draw-up a large quantity of Carb Cleaner.

Flush the PILOT with the Pilot Jet removed pushing the Nozzle of the Syringe into the Pilot Jet orifice and forcing Carb Cleaner through the Passage ... out the Pilot AIR Jet.

Then reverse the Flush, ... AIR Jet through Pilot Jet Orifice.

Do the Main AIR Passage with the Emulsion Tube removed.

(The Main AIR Jet on Mikuni is external. At 3 O'Clock on the Carb Intake Side.)