factory airbox removed, filter pods in place

[klb]

Thanks for the replies. The information was valuable. Now I'm almost finished with the manometer, just curious , what would be more accurate on these home made meters ? Water ? or very thin oil ? Thanks again.

[movenon]

Thanks for the replies. The information was valuable. Now I'm almost finished with the manometer, just curious , what would be more accurate on these home made meters ? Water ? or very thin oil ? Thanks again.

As long as what ever you use stabilizes they will both be the same as far as accuracy.  I use 2 stroke oil.  Works for me and will do no harm if some gets ingested.

I would definitely not use water.... 2 stroke oil is cheap and easy to see.
George

[ribbert]

Thanks for the replies. The information was valuable. Now I'm almost finished with the manometer, just curious , what would be more accurate on these home made meters ? Water ? or very thin oil ? Thanks again.

Did you end up making a 2 or a 4 carb unit?

Noel

[Burns]

The liquid column will bounce around a bit as the pressure waves peak and trough; you need a bit of viscosity to get a decent reading ("stabilize"). As to "very thin oil"   I've used 10-30 motor oil with gfood results. Like the fella said, whatever stabilizes and definitely not water.

[Burns]

shit, I forgot to throw in the ambient temperature into the conversation...fuck it

Scott

re: O2
I said "The effect of altitude on carburation is largely a matter of density"  which addresses the 02 issue. 

At altitude there is less O2 in the charge because there is less air in the charge. I don't think that the ratio of the atmospheric gases (Nitrogen, 02, CO2) changes much if any as a function of altitude.

You say that the air pumped on any given stroke is the same, but actually it is the volume of air that is constant. The mass of that volume decreases as the ambient pressure decreases. 

It also decreases as the ambient temperature rises since hot air is thinner than cold air. 

Power is all about getting as much air/fuel mix in the chamber as you can.  Some drag racers ice down their intake manifolds before a run for a denser charge.

As to rich/lean.  When you rejet for higher altitudes you go down on jet sizes and lean out the mixture. Lower altitude jetting will be rich at higher altitudes.

Cool and Low is the way to go.

[movenon]

The key to stopping the pulsing along with the oil viscosity is to restrict the air flow.  In my picture you will see 2 black fitting in the line. They are restrictors from a Harbor Freight brake bleed kit (5.00).
George

[ribbert]

The liquid column will bounce around a bit as the pressure waves peak and trough; you need a bit of viscosity to get a decent reading ("stabilize"). As to "very thin oil"   I've used 10-30 motor oil with gfood results. Like the fella said, whatever stabilizes and definitely not water.

I think we may have our vacuum lines crossed here. The guy with the fluttering vac on one cylinder is using gauges, not the one that's just built his own.

Noel

[klb]

i put together a four bottle unit with vacuum restricters inline. am going to use 2 stroke oil for the fluid. Brother has an 1980 XS 1100. will see how this turns out. thanks

[klb]

Tried to synch the carbs with the home made manometer, used plastic gatorade bottles and 2 stroke oil, bottles collapsed a fair amount. and was filling bottle two, to where the oil was getting into the vacumn tube, I couldnt keep up with the screw adjustments, shut it down and redistributed the oil evenly. bench synched the carbs again and ended up with the same results on bottle three, a lot of air bubbleing in the other bottles. Bench synched them again and ran it that way without the use of the manometer. Idles smooth. off idle stumbles, have to fan the throttle to get it reved and runs smooth at higher rpms. Am going to put together the 2 carb synch shown on here and try that.

[ribbert]

Tried to synch the carbs with the home made manometer, used plastic gatorade bottles and 2 stroke oil, bottles collapsed a fair amount. and was filling bottle two, to where the oil was getting into the vacumn tube, I couldnt keep up with the screw adjustments, shut it down and redistributed the oil evenly. bench synched the carbs again and ended up with the same results on bottle three, a lot of air bubbleing in the other bottles. Bench synched them again and ran it that way without the use of the manometer. Idles smooth. off idle stumbles, have to fan the throttle to get it reved and runs smooth at higher rpms. Am going to put together the 2 carb synch shown on here and try that.

Something doesn't sound right here, bottles?

All you should have is 4 tubes joined to each other at the bottom, such as the photo below, or two pieces looped at the bottom with a connecting pipe between them, there is no reservoir as such.
You are balancing them against each other, not against atmospheric pressure.
The connecting fittings pictured are automotive vacuum line fittings I happened to have a box of but you could even use garden watering system fittings, anything that fits the tubing.



Some sort of restrictor to calm down the pulsations. The photo below shows plastic dowel cut into short lengths and a small hole drilled through the centre but you could use anything that has the same effect.








....and a board to fasten the tubes to, in this case a fence paling and electrical clips.

I used auto fluid, but once again it could be 2 stroke or old engine oil.

The other thing I did was add some sheaths near the carby end (pictured below) because if the engine is really hot the lines tend to get soft and collapse on themselves giving false readings.



The only thing I had to buy was the tubing, the rest was stuff I had lying around.

The only difference between a 2 tube and a 4 tube set up, other than being a PIA to use, is just ONE connecting tube between the bottom of the two loops.



If it makes it any clearer, just imagine two of Fred's joined together.

Something doesn't sound right from you post, can you post pictures of what you have made?

Noel

[klb]

I must have screwed up. should have used glass bottles not plastic. I found the idea for 4 bottles on youtube. Several ways to make them. I abandoned the 4 bottle set up and went with the single line looped at the bottom and it worked great. Have in line vacuum restricters and is the set up for 2 carb synch. it is shown in the post above. Started at cabs 1&2 then 3&4 then 3&1. Like I said it worked great.  Thanks all.